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Title Page NA 1 NA 1

Foreword i – ii 1 i – ii 1

Contents and Figures 1 – 23 12 1 – 23 12

100 “Manual Description” 1 1 0 0

110 “Nomenclature & References” 1 – 6 3 0 0

130 “Systems Data and Services” 1 – 2 1 0 0

140 “Program Development and Federal Aid Financing”

1 – 2 1 0 0

160 “General” 1 – 2 1 0 0

310 “Preliminary Studies” 1 – 8 4 0 0

325 “Design Matrix Procedures” 1 – 15 10 1 – 15 8

330 “Design Documentation, Approval, and Process Review”

1 – 17 9 1 – 14 7

/s/ Richard B. Albin

Publications Transmittal

To: All metric Design Manual holders

Transmittal Number Date

PT 01-017 May 2001

Publication Title Publication Number

Design Manual (metric) Revision 2001-1 M 22-01

Originating Organization Environmental and Engineering Service Center, Design Office,

Design Policy, Standards, and Safety Research Unit through Engineering Publications

Distributed By Phone Number Signature

Directional Documents and

Engineering Publications

(360) 705-7430

FAX 705-6861

Remarks and Instructions

Remarks:

1. Division 1 chapters that are being deleted will be reorganized and rewritten for a future English

revision.

2. Paper copies of this metric revision will not be distributed. They may be printed from the web.

Instructions:

Page numbers and corresponding sheet-counts are given in the table below to indicate portions of the

Design Manual that are to be removed and inserted to accomplish this revision.

Instructions continued on reverse >>

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Publication Distribution

Form 761-003A EFRevised 3/99

cc: Administrative Services, Directional Documents MS 47408

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Pages Sheets Pages Sheets

410 “Basic Design Level 1 – 2 1 1 – 2 1

430 “Modified Design Level” 1 – 11 6 1 – 11 6

440 “Full Design Level” 1 – 13 7 1 – 15 8

620 “Geometric Plan Elements” 1 – 2 1 1 – 2 1

630 “Geometric Profile Elements” 1 – 2 1 1 – 2 1

640 “Geometric Cross Section” 1 – 42 21 1 – 42 21

650 “Sight Distance” 9 1 9 1

700 “Roadside Safety” 1 – 6 3 1 – 6 3

850 “Traffic Control Signals” 1 – 38 19 1 – 37 19

910 “Intersections at Grade” 1 – 37 19 1 – 38 19

920 “Road Approaches” 7 – 9 2 7 – 9 2

940 “Traffic Interchanges” 3 – 4 1 3 – 4 1

1010 “Auxiliary Lanes” 1 – 8 4 1 – 8 4

1020 “Bicycle Facilities” 1 – 40 20 1 – 32 16

1025 “Pedestrian Design Considerations” (NEW)

NA NA 1 – 19 10

1130 “Retaining Walls and Steep Reinforced Slopes”

1 – 14 7 1 – 14 7

1210 “Hydraulic Design” 1 – 2 1 1 – 2 1

1440 “Surveying and Mapping” 1 – 2 1 1 – 2 1

1450 “Monumentation” 1 – 8 4 1 – 8 4

Index 1 – 19 10 1 – 17 9

Washington State Department of Transportation Design Manual Supplements and Instructional Letters

May 2001

In Effect Chapter Date Type Subject/Title

Yes No No

150 330 1410

01/18/99 IL 4015.00 Right of Way Plan Development Process Improvements (Chapter 330 revised June 1999) (Chapter 1410 revised June 1999)

Yes 1050 940 HOV*

9/28/99 DM Supplement Left-Side HOV Direct Access Connections

Yes 1050 HOV*

05/03/00 DM Supplement Left-Side HOV Parallel On-Connection

Yes 915 07/03/00 IL 4019.01 Roundabouts

* The HOV Direct Access Design Guide, Draft M 22-98

Notes: • Changes since the last revision to the Design Manual are shown in bold print. • Items with No in the In Effect column were superseded by the latest revision and will be

dropped from the next printing of this list. • The listed items marked yes have been posted to the web at the following location:

http://www.wsdot.wa.gov/fasc/engineeringpublications/DesignLettersMemoInstruction.htm

DesignManualM 22-01

Metric

Environmental and Engineering Service CenterDesign Office

Washington State Department of Transportation

Americans with Disabilities Act (ADA) InformationMaterials can be provided in alternative formats: large print, Braille, cassette tape, or on computer disk for people with disabilities by calling the Office of Equal Opportunity (OEO) at 360-705-7097. Persons who are deaf or hard of hearing may contact OEO through the Washington Relay Service at 7-1-1.

Title VI Notice to PublicIt is the Washington State Department of Transportation’s (WSDOT) policy to assure that no person shall, on the grounds of race, color, national origin or sex, as provided by Title VI of the Civil Rights Act of 1964, be excluded from participation in, be denied the benefits of, or be otherwise discriminated against under any of its federally funded programs and activities. Any person who believes his/her Title VI protection has been violated, may file a complaint with WSDOT’s Office of Equal Opportunity (OEO). For Title VI complaint forms and advice, please contact OEO’s Title VI Coordinator at 360-705-7098 or 509-324-6018.

To get the latest information on WSDOT administrative and engineering manuals, sign up for e-mail updates for individual manuals at: www.wsdot.wa.gov/publications/manuals

Washington State Department of Transportation Administrative and Engineering Publications PO Box 47304 Olympia, WA 98504-7304

Phone: 360-705-7430 E-mail: engrpubs@wsdot.wa.gov Internet: www.wsdot.wa.gov/publications/manuals

Design Manual ForewordMay 2001 Metric Version Page i

Foreword

This Design Manual is a guide for our engineering personnel. It providespolicies, procedures, and methods for developing and documenting the designof improvements to the transportation network in Washington State.

The manual supplements the engineering analyses and judgment that must beapplied to improvement and preservation projects. It provides uniform proceduresfor documenting and implementing design decisions.

The designer must understand that the design environment changes rapidly, andoften without warning to the practitioner. To track every change, and to makeimprovements based upon each, is not feasible. The intent of this manual is toprovide a range of recommended values for critical dimensions. Flexibility ispermitted to encourage independent design that is tailored to particular situations.

The fact that new design guidelines are added to the Design Manual through therevision process does not imply that existing features are deficient or inherentlydangerous. Nor does it suggest or mandate immediate engineering review orinitiation of new projects.

Cost-effective and environmentally conscious design is emphasized, andconsideration of the use of the highway corridor by transit, pedestrians, andbicyclists is included. Designers are encouraged to view the highway corridorbeyond the vehicular movement context. To accommodate multimodal use, theguidance provided for one mode is to be appropriately adapted, as needed, at aspecific location. The movement of people, distribution of goods, and provisionof services are thereby emphasized.

The complexity of transportation design requires the designer to make fundamentaltradeoff decisions that balance competing considerations. Although weighing theseconsiderations adds to the complexity of design, it accounts for the needs of aparticular project and the relative priorities of various projects and programs.Improvements must necessarily be designed and prioritized in light of finitetransportation funding.

Updating the manual is a continuing process, and revisions are issued periodically.Questions, observations, and recommendations are invited. Page iii is provided toencourage comments and to assure their prompt delivery. For clarification of thecontent of the manual, contact the Design Office in the Olympia Service Center.The e-mail address is DesignManual@wsdot.wa.gov.

Clifford E. Mansfield, P.E.State Design Engineer

Foreword Design ManualPage ii Metric Version May 2001

Design Manual ContentsMay 2001 Metric Version Page 1

Contents

Date

Division 1 General Information

120 Planning May 2000120.01 General120.02 References120.03 Definitions120.04 Legislation and Policy Development120.05 Planning at WSDOT120.06 Linking Transportation Plans120.07 Linking WSDOT Planning to Programming

Division 2 Hearings, Environmental, and Permits

210 Public Involvement and Hearings December 1998210.01 General210.02 References210.03 Definitions210.04 Public Involvement210.05 Hearings210.06 Environmental Hearing210.07 Corridor Hearing210.08 Design Hearing210.09 Access Hearing210.10 Combined Hearings210.11 Administrative Appeal Hearing210.12 Documentation

220 Project Environmental Documentation June 1989220.01 General220.02 Definitions220.03 Project Classification220.04 Class I, EIS220.05 Class II, CE220.06 Class III, EA/Checklist220.07 Project Reevaluation220.08 Project Reviews

240 Permits and Approvals From OtherGovernmental Agencies September 1990240.01 General (240-13 and 14 June 1989)240.02 United States Department of the Army-Corps of Engineers240.03 United States Coast Guard240.04 United States Forest Service240.05 Federal Aviation Administration240.06 FHWA — Western Federal Lands Highway Division240.07 Federal Energy Regulatory Commission240.08 Environmental Protection Agency

Contents Design ManualPage 2 Metric Version May 2001

Date240.09 Washington State Departments of Fisheries and Wildlife240.10 Washington State Department of Ecology240.11 Washington State Department of Natural Resources240.12 Washington State Department of Labor and Industries240.13 Local Agencies240.14 Utility Agreements

Division 3 Project Documentation

315 Value Engineering August 1998315.01 General315.02 References315.03 Definitions315.04 Procedure315.05 Documentation

325 Design Matrix Procedures May 2001325.01 General325.02 Terminology325.03 Design Matrix Procedures325.04 Selecting a Design Matrix325.05 Project Type325.06 Using a Design Matrix

330 Design Documentation, Approval, and Process Review May 2001330.01 General330.02 References330.03 Purpose330.04 Project Development330.05 Project Definition Phase330.06 Design Documentation330.07 Design Approval330.08 Process Review

Division 4 Project Design Criteria

410 Basic Design Level May 2001410.01 General410.02 Required Safety Basic Items of Work410.03 Minor Safety and Minor Preservation Work

430 Modified Design Level May 2001430.01 General430.02 Design Speed430.03 Roadway Widths430.04 Ramp Lane Widths

Design Manual ContentsMay 2001 Metric Version Page 3

Date430.05 Stopping Sight Distance430.06 Profile Grades430.07 Cross Slope430.08 Fill Slopes and Ditch Inslopes430.09 Intersections430.10 Bridges430.11 Documentation

440 Full Design Level May 2001440.01 General440.02 References440.03 Definitions440.04 Functional Classification440.05 Terrain Classification440.06 Geometric Design Data440.07 Design Speed440.08 Traffic Lanes440.09 Shoulders440.10 Medians440.11 Curbs440.12 Parking440.13 Pavement Type440.14 Structure Width440.15 Grades

Division 5 Soils and Paving

510 Investigation of Soils and Surfacing Materials November 1999510.01 General510.02 References510.03 Materials Sources510.04 Geotechnical Investigation, Design, and Reporting510.05 Use of Geotechnical Consultants510.06 Geotechnical Work by Others510.07 Surfacing Report510.08 Documentation

520 Design of Pavement Structure April 1998520.01 Introduction (520-2 and 3 November 1999)520.02 Estimating Tables

530 Geosynthetics April 1998530.01 General (530-13 November 1999)530.02 References530.03 Geosynthetic Types and Characteristics530.04 Geosynthetic Function Definitions and Applications530.05 Design Approach for Geosynthetics530.06 Design Responsibility530.07 Documentation

Contents Design ManualPage 4 Metric Version May 2001

Date

Division 6 Geometrics

610 Highway Capacity June 1989610.01 General610.02 Definitions and Symbols610.03 Design

620 Geometric Plan Elements April 1998620.01 General 620-1 May 2001)620.02 References (620-2 and 3 April 1998)620.03 Definitions (620-4 November 1999)620.04 Horizontal Alignment620.05 Distribution Facilities620.06 Number of Lanes and Arrangement620.07 Pavement Transitions620.08 Procedures620.09 Documentation

630 Geometric Profile Elements April 1998630.01 General (630-2 May 2001)630.02 References630.03 Vertical Alignment630.04 Coordination of Vertical and Horizontal Alignments630.05 Airport Clearance630.06 Railroad Crossings630.07 Procedures630.08 Documentation

640 Geometric Cross Section May 2001640.01 General640.02 References640.03 Definitions640.04 Roadways640.05 Superelevation640.06 Medians and Outer Separations640.07 Roadsides640.08 Roadway Sections640.09 Documentation

650 Sight Distance April 1998650.01 General (650-3 June 1999)650.02 References (650-4 November 1999)650.03 Definitions (650-8 May 2000)650.04 Passing Sight Distance (650-9 May 2001)650.05 Stopping Sight Distance650.06 Decision Sight Distance

Design Manual ContentsMay 2001 Metric Version Page 5

Date

Division 7 Roadside Safety Elements

700 Roadside Safety August 1997700.01 General (700-1, 2, and 5 May 2001)700.02 References (700-3 April 1998)700.03 Definitions (700-8 June 1999)700.04 Clear Zone700.05 Hazards to be Considered for Mitigation700.06 Median Considerations700.07 Other Roadside Safety Features700.08 Documentation

710 Traffic Barriers May 2000710.01 General710.02 References710.03 Definitions710.04 Project Requirements710.05 Barrier Design710.06 Beam Guardrail710.07 Cable Barrier710.08 Concrete Barrier710.09 Special Use Barriers710.10 Redirectional Land Forms710.11 Bridge Rails710.12 Other Barriers710.13 Documentation

720 Impact Attenuator Systems June 1999720.01 Impact Attenuator Systems720.02 Design Criteria720.03 Selection720.04 Documentation

Division 8 Traffic Safety Elements

810 Construction Work Zone Traffic Control Strategy December 1994810.01 General810.02 References810.03 Definitions810.04 Construction Work Zone Traffic Control Strategy810.05 Procedures

820 Signing November 1999820.01 General820.02 References820.03 Design Components820.04 Overhead Installation820.05 Mileposts820.06 Guide Sign Plan820.07 Documentation

Contents Design ManualPage 6 Metric Version May 2001

Date

830 Delineation May 2000830.01 General830.02 References830.03 Pavement Markings830.04 Guide Posts830.05 Barrier Delineation830.06 Wildlife Warning Reflectors830.07 Documentation

840 Illumination May 2000840.01 General840.02 References840.03 Definitions840.04 Required Illumination840.05 Additional Illumination840.06 Design Criteria840.07 Documentation

850 Traffic Control Signals May 2001850.01 General850.02 References850.03 Definitions850.04 Procedures850.05 Signal Warrants850.06 Conventional Traffic Signal Design850.07 Documentation

860 Intelligent Transportation Systems November 1999860.01 General860.02 References860.03 Traffic Data Collection860.04 Traffic Flow Control860.05 Motorist Information860.06 Documentation

Division 9 Interchanges and Intersections

910 Intersections at Grade May 2001910.01 General910.02 References910.03 Definitions910.04 Design Considerations910.05 Design Vehicle910.06 Right-Turn Corners910.07 Channelization910.08 Roundabouts910.09 U-turns910.10 Sight Distance at Intersections910.11 Traffic Control at Intersections

Design Manual ContentsMay 2001 Metric Version Page 7

Date910.12 Interchange Ramp Terminals910.13 Procedures910.14 Documentation

920 Road Approaches April 1998920.01 General (920-5 and 6 November 1999)920.02 References (920-8 and 9 May 2001)920.03 Definitions920.04 Design Considerations920.05 Road Approach Connection Category920.06 Road Approach Design Template920.07 Sight Distance920.08 Road Approach Spacing and Corner Clearance920.09 Drainage Requirements920.10 Procedures920.11 Documentation

930 Railroad Grade Crossings June 1989930.01 General (930-4, 6 through 12 March 1994)930.02 References930.03 Plans930.04 Traffic Control Systems930.05 Stopping Lanes930.06 Types of Crossing Surfaces930.07 Crossing Closure930.08 Traffic Controls During Construction and Maintenance930.09 Railroad Grade Crossing Orders930.10 Longitudinal Easements From Railroad

940 Traffic Interchanges June 1999940-01 General (940-4 May 2001)940.02 References (940-5 through 7 May 2000)940.03 Definitions (940-10 November 1999)940.04 Interchange Design (940-15, 17 through 20 May 2000)940.05 Ramps (940-23 through 32 May 2000)940.06 Interchange Connections940.07 Ramp Terminal Intersections at Crossroads940.08 Interchanges on Two-Lane Highways940.09 Interchange Plans940.10 Documentation

960 Median Crossovers August 1997960.01 General960.02 Analysis960.03 Design960.04 Approval960.05 Documentation

Contents Design ManualPage 8 Metric Version May 2001

Date

Division 10 Auxiliary Facilities

1010 Auxiliary Lanes November 19991010.01 General (1010-2 and 8 May 2001)1010.02 References1010.03 Definitions1010.04 Climbing Lanes1010.05 Passing Lanes1010.06 Slow Moving Vehicle Turnouts1010.07 Shoulder Driving for Slow Vehicles1010.08 Emergency Escape Ramps1010.09 Chain-Up Areas1010.10 Documentation

1020 Bicycle Facilities May 20011020.01 General1020.02 References1020.03 Definitions1020.04 Planning1020.05 Design1020.06 Documentation

1025 Pedestrian Design Considerations May 20011025.01 General1025.02 References1025.03 Definitions1025.04 Policy1025.05 Pedestrian Human Factors1025.06 Pedestrian Activity Generators1025.07 Pedestrian Facility Design1025.08 Documentation

1030 Safety Rest Areas and Travel Services June 19991030.01 General (1030-3 through 5 November 1999)1030.02 References1030.03 Documentation

1040 Weigh Sites May 20001040.01 General1040.02 Definitions1040.03 Planning, Development, and Responsibilities1040.04 Permanent Facilities1040.05 Portable Facilities1040.06 Shoulder Sites1040.07 Federal Participation1040.08 Procedures1040.09 Documentation

Design Manual ContentsMay 2001 Metric Version Page 9

Date

1050 High Occupancy Vehicle Priority Treatment June 19951050.01 General1050.02 Definitions1050.03 References1050.04 Preliminary Design and Planning1050.05 Operations1050.06 Design Criteria1050.07 Arterial HOV

1060 Transit Benefit Facilities December 19911060.01 Introduction (1060-14 March 1994)1060.02 Definitions (1060-16 through 22 March 1994)

(1060-19 November 1997)1060.03 Park and Ride Lots (1060-23 and 24 July 1994)1060.04 Transfer/Transit Centers (1060-25 through 34 March 1994)1060.05 Bus Stops and Pullouts (1060-35 and 36 July 1994)1060.06 Passenger Amenities (1060-37 and 38 March 1994)1060.07 Roadway and Vehicle Design Criteria Characteristics1060.08 Intersection Radii1060.09 Disabled Accessibility1060.10 References

Division 11 Structures

1110 Site Data for Structures April 19981110.01 General (1110-3 through 5 November 1999)1110.02 References1110.03 Required Data for All Structures1110.04 Additional Data for Waterway Crossings1110.05 Additional Data for Grade Separations1110.06 Additional Data for Widenings1110.07 Documentation

1120 Bridges May 20001120.01 General1120.02 References1120.03 Bridge Location1120.04 Bridge Site Design Elements1120.05 Documentation

1130 Retaining Walls and Steep Reinforced Slopes December 19981130.01 References (1130-1 November 1999)1130.02 General (1130-4 through 13 May 2001)1130.03 Design Principles1130.04 Design Requirements1130.05 Guidelines for Wall/Slope Selection1130.06 Design Responsibility and Process1130.07 Documentation

Contents Design ManualPage 10 Metric Version May 2001

Date

1140 Noise Barriers December 19981140.01 General1140.02 References1140.03 Design1140.04 Procedures1140.05 Documentation

Division 12 Hydraulics

1210 Hydraulic Design December 19981210.01 General (1210-2 May 2001)1210.02 References1210.03 Hydraulic Considerations1210.04 Safety Considerations1210.05 Design Responsibility

Division 13 Roadside Development

1300 Roadside Development and Highway Beautification June 19991300.01 General1300.02 References1300.03 Roadside Classification Plan1300.04 Roadside Manual1300.05 Design Requirements1300.06 Documentation1300.07 Design Recommendations

1310 Contour Grading June 19991310.01 General1310.02 References1310.03 Procedures1310.04 Recommendations

1320 Vegetation June 19991320.01 General1320.02 References1320.03 Discussion1320.04 Recommendations1320.05 Design Guidelines1320.06 Documentation

1330 Irrigation June 19991330.01 General1330.02 References1330.03 Design Considerations

1350 Soil Bioengineering May 20001350.01 General1350.02 References1350.03 Uses1350.04 Design Responsibilities and Considerations1350.05 Documentation

Design Manual ContentsMay 2001 Metric Version Page 11

Date

Division 14 Right of Way and Access Control

1410 Right of Way Considerations June 19991410.01 General1410.02 References1410.03 Special Features1410.04 Easements and Permits1410.05 Programming for Funds1410.06 Appraisal and Acquisition1410.07 Transactions1410.08 Documentation

1420 Access Control Design Policy June 19891420.01 General (1420-4 March 1994)1420.02 Full Access Control Criteria (1420-11 through 21 March 1994)1420.03 Partial Access Control Criteria1420.04 Modified Access Control Criteria1420.05 Access Approaches1420.06 Approaches Between Limited Access

Highways and Adjacent Railroads1420.07 Frontage Roads1420.08 Multiple Use of Right of Way for Nonhighway Purposes1420.09 Modifications to Established Limited Access Plans

1425 Access Point Decision Report May 20001425.01 General1425.02 References1425.03 Definitions1425.04 Procedures1425.05 Access Point Decision Report and Supporting Analyses1425.06 Documentation

1430 Development of Access Control June 19891430.01 General1430.02 Access Report1430.03 Access Hearing

1440 Surveying and Mapping June 19991440.01 General (1440-2 May 2001)1440.02 References1440.03 Procedures1440.04 Datums1440.05 Global Positioning System1440.06 WSDOT Monument Database1440.07 Geographic Information System1440.08 Photogrammetric Surveys1440.09 Documentation

Contents Design ManualPage 12 Metric Version May 2001

Date

1450 Monumentation May 20011450.01 General1450.02 References1450.03 Definitions1450.04 Control Monuments1450.05 Alignment Monuments1450.06 Property Corners1450.07 Other Monuments1450.08 Documentation1450.09 Filing Requirements

1460 Fencing June 19991460.01 General1460.02 References1460.03 Design Criteria1460.04 Fencing Types1460.05 Gates1460.06 Procedure1460.07 Documentation

Index May 2001

Design Manual ContentsMay 2001 Metric Version Page 13

Figures

FigureNumber Title Page Last Date

120-1 Planning Organizations 120-3 May 2000120-2 Transportation Plan Relationships 120-17 May 2000120-3 RTIP, MTIP, and STIP Development Process 120-18 May 2000120-4 Planning and Programming Links 120-19 May 2000

210-1 Sequence for a Hearing 210-16 December 1998220-1 Environmental Process Flow Chart 220-14 June 1989240-1a Permits and Approvals 240-11 September 1990240-1b Permits and Approvals 240-12 September 1990240-2 FAA Notice Requirement Related to Highways 240-13 June 1989240-3 DNR Area Management Units 240-14 June 1989

315-1 Eight-Phase Job Plan for VE Studies 315-5 August 1998315-2 Request for Value Engineering Study 315-6 August 1998315-3 VE Study Team Tools 315-7 August 1998325-1 Design Matrix Selection Guide 325-4 May 2001325-2a NHS Highways in Washington 325-6 May 2001325-2b NHS Highways in Washington 325-7 May 2001325-3a Preservation Program 325-8 May 2001325-3b Improvement Program 325-9 May 2001325-3c Improvement Program (continued) 325-10 May 2001325-4 Design Matrix 1 — Interstate Routes (Main Line) 325-11 May 2001325-5 Design Matrix 2 — Interstate Interchange Areas 325-12 May 2001325-6 Design Matrix 3 — NHS Routes (Main Line) 325-13 May 2001325-7 Design Matrix 4 — Non-Interstate Interchange Areas 325-14 May 2001325-8 Design Matrix 5 — Non-NHS Routes 325-15 May 2001330-1 Design Approval Level 330-7 May 2001330-2 Reviews and Approvals 330-8 May 2001330-3a Reviews and Approvals, Design 330-9 May 2001330-3b Reviews and Approvals, Design (continued) 330-10 May 2001330-4 PS&E Process Approvals 330-11 May 2001330-5a Sample Project Analysis 330-12 May 2001330-5b Sample Project Analysis 330-13 May 2001330-6 Sample Evaluate Upgrade (EU) 330-14 May 2001

430-1 Turning Ramp Lane Widths Modified Design Level 430-1 May 2001430-2 Design Vehicles Modified Design Level 430-3 May 2001430-3 Modified Design Level for Multilane Highways and Bridges 430-4 May 2001430-4 Modified Design Level for Two-Lane Highways and Bridges 430-5 May 2001430-5 Minimum Total Roadway Widths for Two-Lane

Highway Curves 430-6 November 1997

Contents Design ManualPage 14 Metric Version May 2001

FigureNumber Title Page Last Date

430-6 Minimum Total Roadway Widths for Two-LaneHighway Curves, ∆<90˚ — Modified Design Level 430-7 May 2001

430-7 Evaluation for Stopping Sight Distance for Crest VerticalCurves — Modified Design Level 430-8 May 2001

430-8 Evaluation for Stopping Sight Distance for HorizontalCurves — Modified Design Level 430-9 May 2001

430-9 Main Line Roadway Sections — Modified Design Level 430-10 May 2001430-10 Ramp Roadway Sections — Modified Design Level 430-11 May 2001440-1 Desirable Design Speed 440-4 May 2001440-2 Minimum Shoulder Width 440-5 May 2001440-3 Shoulder Width for Curb 440-6 May 2001440-4 Geometric Design Data, Interstate 440-9 May 2001440-5a Geometric Design Data, Principle Arterial 440-10 May 2001440-5b Geometric Design Data, Principle Arterial 440-11 May 2001440-6a Geometric Design Data, Minor Arterial 440-12 May 2001440-6b Geometric Design Data, Minor Arterial 440-13 May 2001440-7a Geometric Design Data, Collector 440-14 May 2001440-7b Geometric Design Data, Collector 440-15 May 2001

510-1 Material Source Development Plan 510-16 November 1999520-1 Estimating — Miscellaneous Tables 520-2 November 1999520-2a Estimating — Asphalt Concrete Pavement and Asphalt

Distribution Tables 520-3 November 1999520-2b Estimating — Asphalt Concrete Pavement and Asphalt

Distribution Tables 520-4 April 1998520-3 Estimating — Bituminous Surface Treatment 520-5 April 1998520-4 Estimating — Base and Surfacing Typical Section

Formulae and Example 520-6 April 1998520-5a Estimating — Base and Surfacing Quantities 520-7 April 1998520-5b Estimating — Base and Surfacing Quantities 520-8 April 1998520-5c Estimating — Base and Surfacing Quantities 520-9 April 1998520-5d Estimating — Base and Surfacing Quantities 520-10 April 1998520-5e Estimating — Base and Surfacing Quantities 520-11 April 1998520-5f Estimating — Base and Surfacing Quantities 520-12 April 1998520-5g Estimating — Base and Surfacing Quantities 520-13 April 1998520-5h Estimating — Base and Surfacing Quantities 520-14 April 1998530-1 Selection Criteria for Geotextile Class 530-3 April 1998530-2 Maximum Sheet Flow Lengths for Silt Fences 530-8 April 1998530-3 Maximum Contributing Area for Ditch and

Swale Applications 530-8 April 1998530-4 Design Process for Drainage and Erosion Control

Geotextiles and Nonstandard Applications 530-12 April 1998530-5 Design Process for Separation, Soil Stabilization,

and Silt Fence 530-13 November 1999530-6a Examples of Various Geosynthetics 530-14 April 1998530-6b Examples of Various Geosynthetics 530-15 April 1998530-7a Geotextile Application Examples 530-16 April 1998530-7b Geotextile Application Examples 530-17 April 1998

Design Manual ContentsMay 2001 Metric Version Page 15

FigureNumber Title Page Last Date

530-7c Geotextile Application Examples 530-18 April 1998530-7d Geotextile Application Examples 530-19 April 1998530-8 Definition of Slope Length 530-20 April 1998530-9 Definition of Ditch or Swale Storage Length

and Width 530-21 April 1998530-10 Silt Fences for Large Contributing Area 530-22 April 1998530-11 Silt Fence End Treatment 530-23 April 1998530-12 Gravel Check Dams for Silt Fences 530-24 April 1998

610-1 Type of Area and Appropriate Level of Service 610-3 June 1989610-2 Adjustment Factor for Type of Multilane Highway and

Development Environment, fE 610-3 June 1989610-3 Maximum ADT vs. Level of Service and Type of Terrain

for Two-Lane Rural Highways 610-4 June 1989610-4 Service Flow Rate per Lane (SFL) for Multilane Highways 610-5 June 1989610-5 Peak-Hour Factors 610-6 June 1989610-6 Service Flow Rates per Lane (SFL) for Freeways 610-6 June 1989620-1a Alignment Examples 620-6 April 1998620-1b Alignment Examples 620-7 April 1998620-1c Alignment Examples 620-8 April 1998630-1a Coordination of Horizontal and Vertical Alignments 630-4 April 1998630-1b Coordination of Horizontal and Vertical Alignments 630-5 April 1998630-1c Coordination of Horizontal and Vertical Alignments 630-6 April 1998630-2 Grade Length 630-7 April 1998630-3 Grading at Railroad Crossings 630-8 April 1998640-1 Minimum Radius for Normal Crown Section 640-5 May 2001640-2 Side Friction Factor 640-5 May 2001640-3 Divided Highway Roadway Sections 640-10 May 2001640-4 Undivided Multilane Highway Roadway Sections 640-11 May 2001640-5 Two-Lane Highway Roadway Sections 640-12 May 2001640-6a Ramp Roadway Sections 640-13 May 2001640-6b Ramp Roadway Sections 640-14 May 2001640-7a Traveled Way Width for Two-Way Two-Lane

Turning Roadways 640-15 May 2001640-7b Traveled Way Width for Two-Way Two-Lane

Turning Roadways 640-16 May 2001640-8a Traveled Way Width for Two-Lane One-Way

Turning Roadways 640-17 May 2001640-8b Traveled Way Width for Two-Lane One-Way

Turning Roadways 640-18 May 2001640-9a Traveled Way Width for One-Lane Turning Roadways 640-19 May 2001640-9b Traveled Way Width for One-Lane Turning Roadways 640-20 May 2001640-9c Traveled Way Width for One-Lane Turning Roadways 640-21 May 2001640-10a Shoulder Details 640-22 May 2001640-10b Shoulder Details 640-23 May 2001640-11a Superelevation Rates (10% Max) 640-24 May 2001640-11b Superelevation Rates (6% Max) 640-25 May 2000640-11c Superelevation Rates (8% Max) 640-26 May 2001

Contents Design ManualPage 16 Metric Version May 2001

FigureNumber Title Page Last Date

640-12 Superelevation Rates for Turning Roadwaysat Intersections 640-27 May 2001

640-13a Superelevation Transitions for Highway Curves 640-28 May 2001640-13b Superelevation Transitions for Highway Curves 640-29 May 2001640-13c Superelevation Transitions for Highway Curves 640-30 May 2001640-13d Superelevation Transitions for Highway Curves 640-31 May 2001640-13e Superelevation Transitions for Highway Curves 640-32 May 2001640-14a Superelevation Transitions for Ramp Curves 640-33 May 2001640-14b Superelevation Transitions for Ramp Curves 640-34 May 2001640-15a Divided Highway Median Sections 640-35 May 2001640-15b Divided Highway Median Sections 640-36 May 2001640-15c Divided Highway Median Sections 640-37 May 2001640-16a Roadway Sections in Rock Cuts Design A 640-38 May 2001640-16b Roadway Sections in Rock Cuts Design B 640-39 May 2001640-17 Roadway Sections With Stepped Slopes 640-40 May 2001640-18a Bridge End Slopes 640-41 May 2001640-18b Bridge End Slopes 640-42 May 2001650-1 Passing Sign Distance 650-1 April 1998650-2 Design Stopping Sight Distance 650-3 June 1999650-3 Existing Stopping Sight Distance 650-3 June 1999650-4 Design Stopping Sight Distance on Grades 650-3 June 1999650-5 Decision Sight Distance 650-5 April 1998650-6 Passing Sight Distance for Crest Vertical Curves 650-6 April 1998650-7 Stopping Sight Distance for Crest Vertical Curves 650-7 April 1998650-8 Stopping Sight Distance for Sag Vertical Curves 650-8 May 2000650-9 Horizontal Stopping Sight Distance 650-9 May 2001

700-1 Design Clear Zone Distance Table 700-8 June 1999700-2 Design Clear Zone Inventory Form 700-9 August 1997700-3 Recovery Area 700-11 August 1997700-4 Design Clear Zone for Ditch Sections 700-12 August 1997700-5 Guidelines for Embankment Barrier 700-13 August 1997700-6 Mailbox Location and Turnout Design 700-14 August 1997700-7 Warrants for Median Barrier 700-15 August 1997700-8 Glare Screens 700-16 August 1997710-1 Type 7 Bridge Rail Upgrade Criteria 710-3 May 2000710-2 Longitudinal Barrier Deflection 710-4 May 2000710-3 Longitudinal Barrier Flare Rates 710-5 May 2000710-4 Guardrail Locations on Slopes 710-6 May 2000710-5 Old Type 3 Anchor 710-8 May 2000710-6 Guardrail Connections 710-9 May 2000710-7 Transitions and Connections 710-10 May 2000710-8 Concrete Barrier Shapes 710-12 May 2000710-9 Single Slope Concrete Barrier 710-13 May 2000710-10 Safety Shaped Concrete Bridge Rail Retrofit 710-16 May 2000710-11a Barrier Length of Need 710-18 May 2000710-11b Barrier Length of Need 710-19 May 2000710-11c Barrier Length of Need on Curves 710-20 May 2000

Design Manual ContentsMay 2001 Metric Version Page 17

FigureNumber Title Page Last Date

710-12 Beam Guardrail Post Installation 710-21 May 2000710-13 Beam Guardrail Terminals 710-22 May 2000710-14 Cable Barrier Locations on Slopes 710-23 May 2000710-15 Thrie Beam Bridge Rail Retrofit Criteria 710-24 May 2000720-1 Impact Attenuator Sizes 720-4 June 1999720-2a Impact Attenuator Systems Permanent Installations 720-6 June 1999720-2b Impact Attenuator Systems Permanent Installations 720-7 June 1999720-2c Impact Attenuator Systems Permanent Installations 720-8 June 1999720-3 Impact Attenuator Systems Work Zone Installations 720-9 June 1999720-4a Impact Attenuator Systems — Older Systems 720-10 June 1999720-4b Impact Attenuator Systems — Older Systems 720-11 June 1999720-5 Impact Attenuator Comparison 720-12 June 1999

820-1a Sign Support Locations 820-5 November 1999820-1b Sign Support Locations 820-6 November 1999820-2 Wood Posts 820-7 November 1999820-3 Steel Posts 820-8 November 1999820-4 Laminated Wood Box Posts 820-9 November 1999830-1 Pavement Marking Material Guide 830-6 May 2000830-2 Guide Post Placement 830-7 May 2000830-3 Wildlife Reflectors on a Tangent Section 830-8 May 2000830-4 Wildlife Reflectors on the Outside of the Curve 830-8 May 2000840-1 Freeway Lighting Applications 840-11 May 2000840-2 Freeway Lighting Applications 840-12 May 2000840-3 Roadway Lighting Applications 840-13 May 2000840-4 Roadway Lighting Applications 840-14 May 2000840-5 Roadway Lighting Applications 840-15 May 2000840-6 Light Levels and Uniformity Ratio 840-16 May 2000840-7 Light Standard Locations 840-17 May 2000840-8 Light Standard heights, Conductor, and Conduit Properties 840-18 May 2000840-9a Line Loss Calculations 840-19 May 2000840-9b Line Loss Calculations 840-20 May 2000840-10a Illumination Calculation Example 840-21 May 2000840-10b Illumination Calculation Example 840-22 May 2000840-10c Illumination Calculation Example 840-23 May 2000840-10d Illumination Calculation Example 840-24 May 2000850-1 Signal Display Maximum Heights 850-13 May 2001850-2 Signal Display Areas 850-14 May 2001850-3 Responsibility for Facilities 850-17 May 2001850-4 Standard Intersection Movements and Head Numbers 850-18 May 2001850-5 Phase Diagrams-Four Way Intersections 850-19 May 2001850-6 Turn Lane Configuration Preventing Concurrent Phasing

Double Left Turn Channelization 850-20 May 2001850-7 Railroad Preemption Phasing 850-21 May 2001850-8a Pedestrian Push Button Locations 850-22 May 2001850-8b Pedestrian Push Button Locations 850-23 May 2001850-9 Dilemma Zone Loop Placement 850-24 May 2001850-10 Railroad Queue Clearance 850-25 May 2001

Contents Design ManualPage 18 Metric Version May 2001

FigureNumber Title Page Last Date

850-11a Intersections With Railroad Crossings 850-26 May 2001850-11b Intersections With Railroad Crossings 850-27 May 2001850-12a Traffic Signal Display Placements 850-28 May 2001850-12b Traffic Signal Display Placements 850-29 May 2001850-12c Traffic Signal Display Placements 850-30 May 2001850-12d Traffic Signal Display Placements 850-31 May 2001850-12e Traffic Signal Display Placements 850-32 May 2001850-13 Mast Arm Signal Moment and Foundation Depths 850-33 May 2001850-14a Strain Pole and Foundation Selection Procedure 850-34 May 2001850-14b Strain Pole and Foundation Selection Procedure 850-35 May 2001850-15 Strain Pole and Foundation Selection Example 850-36 May 2001850-16 Conduit and Conductor Sizes 850-37 May 2001

910-1 Minimum Intersection Spacing 910-4 May 2001910-2 Design Vehicle Types 910-4 May 2001910-3 Intersection Design Vehicle 910-5 May 2001910-4 Left-Turn Storage With Trucks (ft) 910-7 May 2001910-5 U-Turn Spacing 910-10 May 2001910-6 Sight Distance for Turning Vehicles 910-11 May 2001910-7a Turning Path Template 910-14 May 2001910-7b Turning Path Template 910-15 May 2001910-7c Turning Path Template 910-16 May 2001910-8 Right-Turn Corner 910-17 May 2001910-9a Left-Turn Storage Guidelines (Two-Lane, Unsignalized) 910-18 May 2001910-9b Left-Turn Storage Guidelines (Four-Lane, Unsignalized) 910-19 May 2001910-10a Left-Turn Storage Length (Two-Lane, Unsignalized) 910-20 May 2001910-10b Left-Turn Storage Length (Two-Lane, Unsignalized) 910-21 May 2001910-10c Left-Turn Storage Length (Two-Lane, Unsignalized) 910-22 May 2001910-11a Median Channelization (Widening) 910-23 May 2001910-11b Median Channelization — Median Width 23 ft to 26 ft 910-24 May 2001910-11c Median Channelization — Median Width of More Than 26 ft 910-25 May 2001910-11d Median Channelization (Minor Intersection) 910-26 May 2001910-11e Median Channelization (Two-Way Left-Turn Lane) 910-27 May 2001910-12 Right-Turn Lane Guidelines 910-28 May 2001910-13 Right-Turn Pocket and Right-Turn Taper 910-29 May 2001910-14 Right-Turn Lane 910-30 May 2001910-15 Acceleration Lane 910-31 May 2001910-16a Traffic Island Designs 910-32 May 2001910-16b Traffic Island Designs (Compound Curve) 910-33 May 2001910-16c Traffic Island Designs 910-34 May 2001910-17 U-Turn Locations 910-35 May 2001910-18a Sight Distance for Grade Intersection With Stop Control 910-36 May 2001910-18b Sight Distance at Intersections 910-37 May 2001920-1 Road Approach Design Templates 920-3 April 1998920-2 Minimum Corner Clearance 920-4 April 1998920-3 Noncommercial Approach Design Template A 920-5 November 1999920-4 Noncommercial Approach Design Template B and C 920-6 November 1999

Design Manual ContentsMay 2001 Metric Version Page 19

FigureNumber Title Page Last Date

920-5 Commercial Approach — Single ApproachDesign Template D 920-7 April 1998

920-6 Road Approach Sight Distance 920-8 May 2001920-7 Road Approach Spacing and Corner Clearance 920-9 May 2001930-1 M Sight Distance at Railroad Crossing 930-4 March 1994930-2 Guidelines for Railroad Crossing Protection 930-5 June 1989930-3 M Typical Pullout Lane at Railroad Crossing 930-6 March 1994930-4 M Railroad Crossing Plan for Washington Utilities and

Transportation Commission 930-7 March 1994930-5 M Longitudinal Easement Cross Sections 930-8 March 1994930-1 Sight Distance at Railroad Crossing 930-9 March 1994930-3 Typical Pullout Lane at Railroad Crossing 930-10 March 1994930-4 Railroad Crossing Plan for Washington Utilities and

Transportation Commission 930-11 March 1994930-5 Longitudinal Easement Cross Sections 930-12 March 1994940-1 Ramp Design Speed 940-4 May 2001940-2 Maximum Ramp Grade 940-5 May 2000940-3 Ramp Widths 940-5 May 2000940-4 Basic Interchange Patterns 940-11 June 1999940-5 Minimum Ramp Terminal Spacing 940-12 June 1999940-6a Lane Balance 940-13 June 1999940-6b Lane Balance 940-14 June 1999940-7 Main Line Lane Reduction Alternatives 940-15 May 2000940-8 Acceleration Lane Length 940-16 June 1999940-9a On-Connection (Single-Lane, Taper Type) 940-17 May 2000940-9b On-Connection (Single-Lane, Parallel Type) 940-18 May 2000940-9c On-Connection (Two-Lane, Parallel Type) 940-19 May 2000940-9d On-Connection (Two-Lane, Taper Type) 940-20 May 2000940-10 Deceleration Lane Length 940-21 June 1999940-11 Gore Area Characteristics 940-22 June 1999940-12a Off-Connection (Single Lane, Taper Type) 940-23 May 2000940-12b Off-Connection (Single Lane, Parallel Type) 940-24 May 2000940-12c Off-Connection (Single-Lane, One Lane Reduction 940-25 May 2000940-12d Off-Connection (Two-Lane, Taper Type) 940-26 May 2000940-12e Off-Connection (Two-Lane, Parallel Type) 940-27 May 2000940-13a Collector Distributor (Outer Separations) 940-28 May 2000940-13b Collector Distributor (Off-Connections) 940-29 May 2000940-13c Collector Distributor (On-Connections) 940-30 May 2000940-14 Loop Ramps Connections 940-31 May 2000940-15 Length of Weaving Sections 940-32 May 2000940-16 Temporary Ramps 940-33 June 1999940-17 Interchange Plan 940-34 June 1999

1010-1 Rolling Resistance 1010-4 November 19991010-2a Performance for Heavy Trucks 1010-6 November 19991010-2b Speed Reduction Example 1010-7 November 19991010-3 Level of Service — Multilane 1010-8 May 2001

Contents Design ManualPage 20 Metric Version May 2001

FigureNumber Title Page Last Date

1010-4 Auxiliary Climbing Lane 1010-9 November 19991010-5 Warrant for Passing Lanes 1010-10 November 19991010-6 Auxiliary Passing Lane 1010-11 November 19991010-7 Slow Moving Vehicle Turnout 1010-12 November 19991010-8 Typical Emergency Escape Ramp 1010-13 November 19991010-9 Chain-Up/Chain-Off Area 1010-14 November 19991020-1 Shared Use Path 1020-3 May 20011020-2 Bike Lane 1020-4 May 20011020-3 Shared Roadway 1020-4 May 20011020-4 Signed Shared Roadway (Designated Bike Route) 1020-5 May 20011020-5 Obstruction Marking 1020-8 May 20011020-6 Midblock Type Shared Use Path Crossing 1020-9 May 20011020-7 Typical Redesign of a Diagonal Midblock Crossing 1020-10 May 20011020-8 Adjacent Shared Use Path Intersection 1020-11 May 20011020-9 Railroad Crossing for Shared Used Path 1020-12 May 20011020-10 Bicycle Design Speeds 1020-13 May 20011020-11 Bikeway Curve Widening 1020-13 May 20011020-12 R Value and Subsurfacing Needs 1020-14 May 20011020-13 Two-Way Shared Use Path on Separate Right of Way 1020-18 May 20011020-14 Two-Way Shared Use Path Adjacent to Roadway 1020-19 May 20011020-15 Typical Bike Lane Cross Sections 1020-20 May 20011020-16 Bikeways on Highway Bridges 1020-21 May 20011020-17 Refuge Area 1020-22 May 20011020-18 At-Grade Railroad Crossings 1020-23 May 20011020-19 Stopping Sight Distance 1020-24 May 20011020-20 Sight Distance for Crest Vertical Curves 1020-25 May 20011020-21 Lateral Clearance on Horizontal Curves 1020-26 May 20011020-22 Typical Bicycle/Auto Movements at Intersections

of Multilane Streets 1020-27 May 20011020-23a Bicycle Crossing of Interchange Ramp 1020-28 May 20011020-23b Bicycle Crossing of Interchange Ramp 1020-29 May 20011020-24 Bike Lanes Approaching Motorists’ Right-Turn-Only Lanes 1020-30 May 20011020-25 Typical Pavement Marking for Bike Lane on

Two-Way Street 1020-31 May 20011020-26 Typical Bike Lane Pavement Markings at T-Intersections 1020-32 May 20011025-1 Trail Width and Grades 1025-5 May 20011025-2a Pedestrian Walkways 1025-10 May 20011025-2b Pedestrian Walkways 1025-11 May 20011025-3 Sidewalk Recommendations 1025-12 May 20011025-4 Marked Crosswalk Recommendations at Unsignalized

Pedestrian Crossings 1025-13 May 20011025-5 Crosswalk Locations 1025-14 May 20011025-6a Sight Distance at Intersections 1025-15 May 20011025-6b Sight Distance at Intersections 1025-16 May 20011025-7 Sidewalk Bulb Outs 1025-17 May 20011025-8 Midblock Pedestrian Crossing 1025-18 May 20011025-9 Sidewalk Ramp Drainage 1025-19 May 2001

Design Manual ContentsMay 2001 Metric Version Page 21

FigureNumber Title Page Last Date

1030-1 Typical Truck Storage 1030-3 November 19991030-2 Typical Single RV Dump Station Layout 1030-4 November 19991030-3 Typical Two RV Dump Station Layout 1030-5 November 19991040-1 Truck Weigh Site (Multilane Highway) 1040-6 May 20001040-2 Truck Weigh Site (Two Lane Highway) 1040-7 May 20001040-3 Vehicle Inspection Installation 1040-8 May 20001040-4 Minor Portable Scale Site 1040-9 May 20001040-5 Major Portable Scale Site 1040-10 May 20001040-6 Small shoulder Site 1040-11 May 20001040-7 Large Shoulder Site 1040-12 May 20001040-8a MOU Related to Vehicle Weighing and Equipment

Inspection Facilities on State Highways 1040-13 May 20001040-8b MOU Related to Vehicle Weighing and Equipment

Inspection Facilities on State Highways 1040-14 May 20001040-8c MOU Related to Vehicle Weighing and Equipment

Inspection Facilities on State Highways 1040-15 May 20001040-8d MOU Related to Vehicle Weighing and Equipment

Inspection Facilities on State Highways 1040-16 May 20001040-8e MOU Related to Vehicle Weighing and Equipment

Inspection Facilities on State Highways 1040-17 May 20001050-1 M Typical Concurrent Flow Lanes 1050-11 June 19951050-2 M Roadway Widths for Three-Lane HOV On and Off Ramps 1050-12 June 19951050-3a M Separated Roadway Single-Lane, One-Way or Reversible 1050-13 June 19951050-3b M Separated Roadway Multi-Lane, One-Way or Reversible 1050-14 June 19951050-4a M Single-Lane Ramp Meter With HOV Bypass 1050-15 June 19951050-4b M Two-Lane Ramp Meter With HOV Bypass 1050-16 June 19951050-5a M Typical HOV Flyover 1050-17 June 19951050-5b M Typical Inside Lane On Ramp 1050-18 June 19951050-5c M Inside Single-Lane On Ramp 1050-19 June 19951050-6 M Typical Slip Ramp 1050-20 June 19951050-7a M Enforcement Area (One Direction Only) 1050-21 June 19951050-7b M Median Enforcement Area 1050-22 June 19951050-7c M Bidirectional Observation Point 1050-23 June 19951050-1 Typical Concurrent Flow Lanes 1050-24 June 19951050-2 Roadway Widths for Three-Lane HOV On and Off Ramps 1050-25 June 19951050-3a Separated Roadway Single-Lane, One-Way or Reversible 1050-26 June 19951050-3b Separated Roadway Multi-Lane, One-Way or Reversible 1050-27 June 19951050-4a Single-Lane Ramp Meter With HOV Bypass 1050-28 June 19951050-4b Two-Lane Ramp Meter With HOV Bypass 1050-29 June 19951050-5a Typical HOV Flyover 1050-30 June 19951050-5b Typical Inside Lane On Ramp 1050-31 June 19951050-5c Inside Single-Lane On Ramp 1050-32 June 19951050-6 Typical Slip Ramp 1050-33 June 19951050-7a Enforcement Area (One Direction Only) 1050-34 June 19951050-7b Median Enforcement Area 1050-35 June 19951050-7c Bidirectional Observation Point 1050-36 June 1995

Contents Design ManualPage 22 Metric Version May 2001

FigureNumber Title Page Last Date

1060-1 M Bus Berth Design 1060-14 March 19941060-2 Transit Center Sawtooth Bus Berth Design Example 1060-15 December 19911060-3 M Bus Turnout Transfer Center 1060-16 March 19941060-4 M Off-Street Transfer Center 1060-17 March 19941060-5 M Minimum Bus Zone Dimensions 1060-18 March 19941060-6 Bus Stop Pullouts, Arterial Streets 1060-19 November 19971060-7 M Minimum Bus Zone and Pullout after Right Turn

Dimensions 1060-20 March 19941060-8 M Shelter Siting 1060-21 March 19941060-9 M Typical Bus Shelter Design 1060-22 March 19941060-10 M Design Vehicle Turning Movements 1060-23 July 19941060-11 M Turning Template for Articulated Bus 1060-24 July 19941060-12 M Intersection Design 1060-25 March 19941060-13 M Cross-Street Width Occupied by Turning Vehicle

for Various Angles of Intersection and Curb Radii 1060-26 March 19941060-1 Bus Berth Design 1060-27 March 19941060-3 Bus Turnout Transfer Center 1060-28 March 19941060-4 Off-Street Transfer Center 1060-29 March 19941060-5 Minimum Bus Zone Dimensions 1060-30 March 19941060-6 Bus Stop Pullouts, Arterial Streets 1060-31 March 19941060-7 Minimum Bus Zone and Pullout after Right Turn

Dimensions 1060-32 March 19941060-8 Shelter Siting 1060-33 March 19941060-9 Typical Bus Shelter Design 1060-34 March 19941060-10 Design Vehicle Turning Movements 1060-35 July 19941060-11 Turning Template for Articulated Bus 1060-36 July 19941060-12 Intersection Design 1060-37 March 19941060-13 Cross-Street Width Occupied by Turning Vehicle

for Various Angles of Intersection and Curb Radii 1060-38 March 1994

1110-1 Bridge Site Data Check List 1110-5 November 19991120-1a Railroad Vertical Clearance — New Bridge Construction 1120-5 May 20001120-1b Railroad Vertical Clearance — Existing Bridge

Modifications 1120-6 May 20001130-1a Typical Mechanically Stabilized Earth Gravity Walls 1130-22 December 19981130-1b Typical Prefabricated Modular Gravity Walls 1130-23 December 19981130-1c Typical Rigid Gravity, Semigravity Cantilever,

Nongravity Cantilever, and Anchored Walls 1130-24 December 19981130-1d Typical Rockery and Reinforced Slope 1130-25 December 19981130-2 MSE Wall Drainage Detail 1130-26 December 19981130-3 Retaining Walls With Traffic Barriers 1130-27 December 19981130-4a Retaining Wall Design Process 1130-28 December 19981130-4b Retaining Wall Design Process — Proprietary 1130-29 December 19981130-5 Retaining Wall Bearing Pressure 1130-30 December 19981140-1 Standard Noise Wall Types 1140-3 December 1998

Design Manual ContentsMay 2001 Metric Version Page 23

FigureNumber Title Page Last Date

1410-1 Appraisal and Acquisition 1410-6 June 19991420-1a Full Access Control Criteria 1420-10 June 19891420-1b M Access Control for Typical Interchange 1420-11 March 19941420-1c M Access Control at Ramp Termination 1420-12 March 19941420-2a Partial Access Control Criteria 1420-13 March 19941420-2b M Access Control for Intersection at Grade 1420-14 March 19941420-3 M Access Control Limits at Intersections 1420-15 March 19941420-1b Access Control for Typical Interchange 1420-17 March 19941420-1c Access Control at Ramp Termination 1420-18 March 19941420-2a Partial Access Control Criteria 1420-19 March 19941420-2b Access Control for Intersection at Grade 1420-20 March 19941420-3 Access Control Limits at Intersections 1420-21 March 19941425-1a Access Point Decision Report Content and Review Levels 1425-11 May 20001425-1b Access Point Decision Report Content and Review Levels 1425-12 May 20001425-2 Access Point Decision Report Possibly Not Required 1425-13 May 20001425-3a Access Point Decision Report Flow Chart 1425-14 May 20001425-3b Access Point Decision Report Flow Chart 1425-15 May 20001430-1 Access Report Plan 1430-4 June 19891430-2 Access Hearing Plan 1430-5 June 19891440-1a Interagency Agreement 1440-4 June 19991440-1b Interagency Agreement 1440-5 June 19991450-1 Monument Documentation Summary 1450-4 May 20011450-2a DNR Permit Application 1450-5 May 20011450-2b DNR Completion Record Form 1450-6 May 20011450-3a Land Corner Record 1450-7 May 20011450-3b Land Corner Record 1450-8 May 2001

5:P65:DP/DMM

Design Manual Design Matrix ProceduresMay 2001 Metric Version Page 325-1

325 Design Matrix Procedures

replacement; joint and shoulder repair; and bridgework such as crack sealing, joint repair, seismicretrofit, scour countermeasures and painting.Preventive maintenance projects must notdegrade any existing safety or geometric aspectsof the facility.

In Design Matrices 1 and 2 and in Figure 330-1,the term New/Reconstruction includes thefollowing types of work:

• Capacity changes: add a through lane, convert ageneral purpose (GP) lane to a special purposelane (such as an HOV lane), or convert a highoccupancy vehicle ( HOV) lane to GP.

• Other lane changes: add or eliminate acollector-distributor or auxiliary lane. (Arural truck climbing lane that, for its entirelength, meets the warrants in Chapter 1010is not considered new/reconstruction.)

• Pavement reconstruction: full depth PCC orAC pavement replacement.

• New interchange

• Changes in interchange type such as diamondto directional

• New or replacement bridge (main line)

The HAL, HAC, PAL, and Risk locationmentioned in the notes on Design Matrices 3, 4,and 5 are high accident locations (HAL), highaccident corridors (HAC), pedestrian accidentlocations (PAL), and locations that have a highprobability of run-off-the-road accidents basedon existing geometrics (Risk).

The Non-Interstate Freeway mentioned onDesign Matrices 3, 4, and 5 is multilane, dividedhighway with full access control.

The Master Plan for Access Control mentionedin the notes on Design Matrices 3, 4, and 5 isavailable from the Olympia Service Center,Design Office, Access and Hearings Unit.

The corridor or project analysis mentioned innotes 2 and 4 (on Design Matrices 3, 4, and 5)is the justification needed to support a change

325.01 General325.02 Terminology325.03 Design Matrix Procedures325.04 Selecting a Design Matrix325.05 Project Type325.06 Using a Design Matrix

325.01 GeneralThis highway Design Manual provides guidancefor three levels of design for highway projects:the basic, modified, and full design levels. Thedesign matrices in this chapter are used to iden-tify the design level(s) for a project and theassociated processes and approval authority forallowing design variances. The matrices addressthe majority of preservation and improvementprojects and focus on those design elements thatare of greatest concern in project development.

The design matrices are five tables that areidentified by route type. Two of the matricesapply to Interstate highways. The other threematrices apply to preservation and improvementprojects on non-Interstate highways.

325.02 TerminologyThe National Highway System (NHS) consistsof highways designated as a part of the InterstateSystem, other urban and rural principal arterials,and highways that provide motor vehicle accessto facilities such as and a major port, airport,public transportation facility, or other intermodaltransportation facility. The NHS includes ahighway network that is important to the UnitedStates strategic defense policy and providesdefense access, continuity, and emergencycapabilities for the movement of personnel,materials, and equipment during times of war andpeace. It also includes major network connectorsthat provide motor vehicle access between majormilitary installations and other highways that arepart of the strategic highway network.

The Preventive Maintenance mentioned underproject type on Interstate Design Matrices 1 and 2includes roadway work such as pavementpatching; restoration of drainage system; panel

Design Matrix Procedures Design ManualPage 325-2 Metric Version May 2001

in design level from the indicated level. Theanalysis can be based on route continuity, andother existing features, as well as the recommen-dations for future improvements in an approvedRoute Development Plan.

(1) Project TypesDiamond Grinding is grinding a concretepavement to remove surface wear or jointfaulting.

Milling with AC Inlays is removal of a specifiedthickness of asphalt surfacing, typically from thetraveled lanes, and then overlaying with asphaltconcrete at the same specified thickness.

Nonstructural Overlay is an asphalt concretepavement overlay that is placed to minimize theaging effects and minor surface irregularities ofthe existing asphalt concrete pavement structure.The existing pavement structure is not showingextensive signs of fatigue (longitudinal or alliga-tor cracking in the wheel paths). Nonstructuraloverlays are typically less than 40 mm thick.

AC Structural Overlay is an asphalt concretepavement overlay that is placed to increase theload carrying ability of the pavement structure.Structural overlay thickness is greater than orequal to 40 mm.

PCC Overlay is a Portland cement concretepavement overlay of an existing PCC orAC pavement.

Dowel Bar Retrofit is re-establishing the loadtransfer efficiencies of the existing concretejoints and transverse cracks by the cutting ofslots, placement of epoxy coated dowel bars,and placement of high-early strength,non-shrink concrete.

Bridge Deck Rehabilitation is repair of anydelaminated concrete bridge deck and addinga protective overlay that will prevent furthercorrosion of the reinforcing steel.

Safety, All Others includes collision reduction,collision prevention, channelization, andsignalization projects.

Safety, At Grade is a project on a multilanehighway to build grade separation facilities thatreplace the existing intersection.

Bridge Restriction projects are listed undereconomic development because these bridges donot have any structural problems. However, if thevertical or load capacity restrictions are removed,then it will benefit the movement of commerce.

(2) Design ElementsThe following elements are shown on the DesignMatrices. If the full design level applies, seethe chapters listed below. If basic design levelapplies, see Chapter 410. If the modified designlevel applies, see Chapter 430.

Horizontal Alignment is the horizontal attributesof the roadway including horizontal curvature,superelevation, and stopping sight distance; allbased on design speed. (See Chapter 620 forhorizontal alignment, Chapter 640 forsuperelevation, Chapter 650 for stopping sightdistance, and Chapter 440 for design speed.)

Vertical Alignment is the vertical attributes ofthe roadway including vertical curvature, profilegrades, and stopping sight distance; all based ondesign speed. (See Chapter 630 for verticalalignment, Chapters 440 and 630 for grades,Chapter 650 for stopping sight distance, andChapter 440 for design speed.)

Lane Width is the distance between lane lines.(See Chapter 640.)

Shoulder Width is the distance between theoutside or inside edge line and the edge ofin-slope, or face of barrier. (See Chapter 640.)

Lane and Shoulder Taper (pavementtransitions) are the rate and length of transitionof changes in width of roadway surface. (SeeChapters 440 and 620.)

Median Width is the distance between insideedge lines. (See Chapters 440 and 640.)

Cross Slope, Lane is the rate of elevation changeacross a lane. This element includes the algebraicdifference in cross slope between adjacent lanes.(See Chapter 640.)

Cross Slope, Shoulder is the rate of elevationchange across a shoulder. (See Chapter 640.)

On/Off Connection is the widened portion ofthe main line beyond the ramp terminal. (SeeChapter 940.)

Design Manual Design Matrix ProceduresMay 2001 Metric Version Page 325-3

Fill/Ditch Slope is downward slope from edgeof shoulder to bottom of ditch or catch. (SeeChapter 640.)

Access is means of entering or leaving a publicstreet or highway from an abutting privateproperty or another public street or highway.(See Chapter 1420.)

Clear Zone is the total roadside border area,starting at the edge of the traveled way, availablefor use by errant vehicles. This area may consistof a shoulder, a recoverable slope, a nonrecover-able slope, and/or a clear run-out area. (SeeChapter 700.)

Signing, Delineation, Illumination are signs,guide posts, pavement markings, and lighting.(See Chapter 820 for signing, Chapter 830 fordelineation, and Chapter 840 for illumination.)

Basic Safety is the safety items listed inChapter 410.

Bridge Lane Width is the distance betweenlane lines on a structure. (See Chapters 440, 640and 1120.)

Bridge Shoulder Width is the distance betweenoutside or inside edge line and face of curb orbarrier, whichever is less. (See Chapters 440, 640and 1120.)

Bridge Vertical Clearance is the minimumheight between the roadway including shoulderand an overhead obstruction. (See Chapter 1120.)

Bridge Structural Capacity is the load bearingability of a structure. (See Chapters 440 and1120.)

Intersections Turning Radii See Chapter 910for definition.

Intersections Angle See Chapter 910 fordefinition.

Intersections Sight Distance See Chapter 910for definition.

Barriers Terminals and Transitions Section —Terminals are crashworthy end treatment forlongitudinal barriers that is designed to reducethe potential for spearing, vaulting, rolling, or

excessive deceleration of impacting vehicles fromeither direction of travel. Impact attenuators areconsidered terminals and beam guardrail termi-nals include anchorage. — Transitions aresections of barriers used to produce a gradualstiffening of a flexible or semi-rigid barrier as itconnects to a more rigid barrier or fixed objects.(See Chapter 710 and 720.)

Barriers Standard Run are guardrail and otherbarriers excluding terminals, transitions, attenua-tors, and bridge rails. (See Chapter 710.)

Barriers Bridge Rail is barrier on a bridgeexcluding transitions. (See Chapter 710.)

325.03 Design Matrix ProceduresWhen scoping, or designing a project, thefollowing steps are used to select and apply thedesign matrix. Each step is further explained inthis chapter.

• Select a design matrix by identifying theroute: Interstate, NHS, or non-NHS

• Within the design matrix: for Matrices 1and 2 select the row by the type of work andfor Matrices 3, 4 and 5 select the row byidentifying the project type

• Use the design matrix to determine the designlevel for the design elements of the project.Apply the appropriate design levels anddocument the design decisions as requiredby this chapter and Chapter 330.

325.04 Selecting a Design MatrixSelection of a design matrix is based on highwaysystem (Interstate, non-NHS and other NHS) andlocation (main line, interchange). (See Figure325-1.) Figures 325-2a and 2b provide a list ofNHS highways in the state of Washington. Thedesign matrices are shown in Figures 325-4through 325-8. Follow Design Manual guidancefor all projects except as noted in the designmatrices and elsewhere as applicable.

Design Matrix Procedures Design ManualPage 325-4 Metric Version May 2001

Route Project

Main InterchangeLine Area

Interstate Matrix 1 Matrix 2

NHS Matrix 3 Matrix 4

Non-NHS Matrix 5 Matrix 4

Design Matrix Selection GuideFigure 325-1

325.05 Project TypeIn the design matrices, row selection is based onproject type or type of work. The Project Sum-mary defines and describes the project. (ProjectSummary is discussed in Chapter 330.) For non-NHS and NHS routes, the project’s program/subprogram might be sufficient information foridentifying project type.

For project types not listed in the design matrices,consult the OSC Design Office for guidance.

See Figures 325-3a through 3c for program andsubprogram titles and definitions. The varioussources of funds for these subprograms carryeligibility requirements that the designers andprogram managers must identify and monitorthroughout project development — especially ifthe type of work changes — to ensure accuracywhen writing agreements and to avoid delayingadvertisement for bids.

Some projects involve work from several subpro-grams. In such cases, identify the various limitsof the project that apply to each subprogram.Where the project limits overlap, apply thehigher design level to the overlapping portion.

325.06 Using a Design MatrixThe column headings on a design matrix aredesign elements. They are based on the follow-ing thirteen FHWA controlling design criteria:design speed, lane width, shoulder width, bridgewidth, structural capacity, horizontal alignment,vertical alignment, grade, stopping sight distance,cross slope, superelevation, vertical clearance,

and horizontal clearance. For the column head-ings, some of these controlling criteria have beencombined (for example, design speed is part ofhorizontal and vertical alignment).

For Improvement type projects, full design levelapplies to all design elements except as noted indesign matrices and in Design Manual chaptersas applicable.

A blank cell on a design matrix signifies that thedesign element will not be addressed because it isbeyond the scope of the project.

(1) Design LevelsIn the Interstate matrices, full design level appliesunless otherwise noted.

In the non-Interstate matrices, design levels arenoted in the cells by B, M, F, and a numbercorresponding to a footnote on the matrix.

The design levels of basic, modified, and full(B, M, and F) were used to develop the designmatrices. Each design level is based on theinvestment intended for the route type and typeof work. (For example, the investment is higherfor Interstate reconstruction than for an overlayon a non-NHS route.)

Basic design level (B) preserves pavementstructures, extends pavement service life, andmaintains safe operations of the highway.See Chapter 410.

Modified design level (M) preserves andimproves existing roadway geometrics, safety,and operational elements. See Chapter 430.

Full design level (F) improves roadwaygeometrics, safety, and operational elements.See Chapter 440 and other applicable DesignManual chapters for design guidance.

(2) Design VariancesTypes of design variances are design exceptions(DE), evaluate upgrades (EU), and deviations.

Design exception (DE) in a matrix cell indicatesan existing condition that is not standard, relativeto the current design level. The condition willnot be corrected unless a need has been identifiedin the Highway System Plan and prioritizedin accordance with the programming

Design Manual Design Matrix ProceduresMay 2001 Metric Version Page 325-5

process. A design exception must be identified inthe project documents but no further justificationis required.

Evaluate upgrade (EU) in a matrix cell indicatesthat an existing nonstandard condition must beevaluated to determine the impacts and costeffectiveness of upgrading to the applicabledesign level. The decision whether or not toupgrade, and its analyses and justification,must be provided in the project documentation.See Chapter 330.

A deviation is required when an existing orproposed design element does not meet or exceedthe applicable design level for the project andneither DE nor EU processing is indicated.Documentation of a deviation must containjustification and it must be approved at theappropriate approval level. The analyses andjustification must be provided in the deviationrequest. See Chapter 330 for requirements.

P65:DP/DMM

Design Matrix Procedures Design ManualPage 325-6 Metric Version May 2001

Beginning Begin Ending EndState Route NHS Route Designation SR MP ARM SR MP ARM

US 2 I-5 to Idaho State Line 0.00 0.00 334.51 326.64

US 2 Couplet Everett Couplet 0.00 0.00 1.64 0.87

US 2 Couplet Brown Street Couplet 287.45 0.00 288.08 0.63

US 2 Couplet Division Street Couplet 289.19 0.00 290.72 1.53

SR 3 SR 101 to SR 104 0.00 0.00 60.02 59.81

SR 4 SR 101 to I-5 0.00 0.00 62.28 62.27

I-5 Oregon State Line to Canadian Border 0.00 0.00 276.56 276.62

SR 8 SR 12 to SR 101 0.00 0.00 20.67 20.67

SR 9 SR 539 to Canadian Border 93.61 93.52 98.17 98.08

SR 9 Spur Sumas Spur 98.00 0.00 98.25 0.24

SR 11 I-5 to Alaskan Ferry Terminal 19.93 19.93 21.28 21.28

US 12 SR 101 to Idaho State Line 0.00 0.00 434.19 430.76

US 12 Couplet Aberdeen Couplet 0.33 0.00 0.68 0.35

SR 14 I-5 to SR 97 0.00 0.00 101.02 100.93

SR 14 Spur Maryhill Spur 100.66 0.00 101.05 0.39

SR 16 I-5 to SR 3 0.00 0.00 29.19 27.01

SR 16 Spur SR 16 to SR 3 28.74 0.00 29.13 0.39

SR 17 SR 395 to I-90 7.43 0.00 50.89 43.40

SR 18 So. Federal Way Park & Ride to I-5 2.20B 0.00 0.00 0.53

SR 18 I-5 to I-90 0.00 0.53 27.91 28.41

SR 20 SR 101 to I-5 0.00 0.00 59.54 59.49

SR 20 Spur SR 20 to San Juan Ferry 47.89 0.00 55.67 7.78

SR 22 SR 97 to I-82 0.70 0.00 4.00 3.31

SR 26 I-90 to US 195 0.00 0.00 133.53 133.61

SR 26 Spur SR 26 to US 195 133.44 0.00 133.51 0.07

SR 28 SR 2 to SR 281 0.00B 0.00 29.77 33.91

I-82 I-90 to Oregon State Line 0.00 0.00 132.60 132.57

I-90 I-5 to Idaho State Line 1.94 0.00 299.82 297.52

I-90 Reverse Lane Reversible lane 1.99 0.00 9.44 7.45

SR 96 McCollum Park and Ride to I-5 0.00 0.00 0.52 0.52

US 97 Oregon State Line to SR 22 0.00B 0.00 61.44 61.30

US 97 I-90 to Canadian Border 133.90 118.80 336.48 321.62

US 97 Couplet Maryhill Couplet 2.59 0.00 2.68 0.09

US 97 Spur SR 97 to SR 2 (Orondo) 213.36 0.00 213.62 0.26

US 97 Y SR 970 to SR 97

SR 99 188th to SeaTac Airport 18.35 14.70 18.77 15.12

SR 99 SR 509 to SR 104 26.04 22.40 43.60 39.84

US 101 Oregon State Line to SR 401 0.00 0.00 0.46 0.46

US 101 SR 4 to I-5 28.89 28.89 367.41 365.78

US 101 Couplet Aberdeen Couplet 87.49 0.00 91.66 4.17

US 101 Couplet Port Angeles Couplet 249.65 0.00 251.32 1.67

SR 104 SR 101 to I-5 0.20 0.00 29.67 29.14

SR 109 Pacific Beach Access 0.00 0.00 30.25 30.29

SR 125 Oregon State Line to SR 12 0.00 0.00 6.09 6.08

SR 125 Spur SR 125 to SR 12 6.09 0.00 6.76 0.67

SR 127 SR 12 to SR 26 0.03 0.00 27.05 27.05

SR 128 SR 12 to Idaho State Line 0.00 0.00 2.30 2.30

This list provided by the OSC Planning Office

NHS Highways in WashingtonFigure 325-2a

Design Manual Design Matrix ProceduresMay 2001 Metric Version Page 325-7

NHS Highways in Washington (continued)Figure 325-2b

Beginning Begin Ending EndState Route NHS Route Designation SR MP ARM SR MP ARM

SR 166 Naval Fuel Depot 0.02 0.00 3.40 3.38

SR 167 I-5 to I-405 0.00 0.00 27.28 28.60

I-182 I-82 to US 395 0.00 0.00 15.19 15.19

US 195 Idaho State Line to I-90 0.00B 0.00 95.99 93.37

US 195 Spur US 195 to Idaho State Line 0.06 0.00 0.60 0.54

I-205 Oregon State Line to I-5 26.59 0.00 37.16 10.57

SR 240 Hanford Access 30.63 28.86 34.87 33.10

SR 270 SR 195 to Idaho 0.00 0.00 9.89 9.89

SR 270 Pullman Couplet 2.67 0.00 2.90 0.23

SR 270 SR 195 Y Connection 0.00 0.00 0.38 0.38

SR 281 SR 28 to I-90 0.00 0.00 10.55 10.55

SR 281 Spur SR 281 to I-90 2.65 0.00 4.34 1.69

SR 303 SR 3 to SR 304 0.00B 0.00 8.73 8.89

SR 304 SR 16 to Bremerton Ferry 0.00 0.00 3.51 3.24

SR 305 SR 3 to Winslow Ferry 0.02 0.00 13.52 13.50

SR 307 SR 305 to SR 104 0.00 0.00 5.25 5.25

SR 310 SR 3 to SR 304 0.00 0.00 1.84 1.84

US 395 Congressional High Priority Route 13.05 13.05 270.26 275.09

SR 401 SR 101 to SR 4 0.00 0.00 12.13 12.13

I-405 I-5 to I-5 0.00 0.00 30.32 30.30

SR 432 SR 4 to I-5 0.00 0.00 10.33 10.32

SR 433 Oregon State Line to SR 432 0.00 0.00 0.94 0.94

SR 500 I-5 to SR 503 0.00 0.00 5.96 5.96

SR 501 I-5 to Port of Vancouver 0.00 0.00 3.83 3.42

SR 502 I-5 to SR 503 0.00B 0.00 7.56 7.58

SR 503 SR 500 to SR 502 0.00 0.00 8.09 8.09

SR 509 SR 99 to 12th Place S 24.35B 26.13 29.83 33.11

SR 509 Pacific Ave. to Marine View Drive 0.22 1.44 3.20 4.42

SR 512 I-5 to SR 167 0.00 0.00 12.06 12.06

SR 513 Sandpoint Naval Air Station 0.00 0.00 3.35 3.35

SR 516 I-5 to SR 167 2.03 2.02 4.72 4.99

SR 518 I-5 to SR 509 0.00 0.00 3.81 3.42

SR 519 I-5 to Seattle Ferry Terminal 0.00 0.00 1.14 1.14

SR 520 I-5 to SR 202 0.00 0.00 12.83 12.82

SR 522 I-5 to SR 2 0.00 0.00 24.68 24.68

SR 524 Lynnwood Park and Ride to I-5 4.64 4.76 5.20 5.32

SR 524 Spur Cedar Way Spur - Lynnwood Park and Ride to I-5 4.64 0.00 5.14 0.50

SR 525 I-5 to SR 20 0.00 0.00 30.49 30.72

SR 526 SR 525 to I-5 0.00 0.00 4.52 4.52

SR 529 Everett Homeport 0.00 0.00 2.20 2.20

SR 539 I-5 to Canadian Border 0.00 0.00 15.16 15.16

SR 543 I-5 to Canadian Border 0.00 0.00 1.09 1.09

SR 546 SR 539 to Canadian Border 0.00 0.00 8.02 8.02

I-705 I-5 to Schuster Parkway 0.00 0.00 1.50 1.50

SR 970 I-90 to SR 97 0.00 0.00 10.31 10.31

SR 970 Y Y connection to US 97 0.00 0.00 0.10 0.10

This list provided by the OSC Planning Office

Design Matrix Procedures Design ManualPage 325-8 Metric Version May 2001

P Preservation — Preserve the highway infrastructure cost effectively to protect the publicinvestment.

P1 Roadway

1. Repave highways at regular intervals to minimize long-term costs.

2. Restore existing safety features.

P2 Structures

1. Rehabilitate or replace existing bridges and other structures to preserve operational andstructural integrity.

2. Reduce the risk of naturally caused catastrophic bridge failures.

P3 Other Facilities

1. Refurbish rest areas to extend service life and improve safety.

2. Construct weigh facilities to ensure enforcement across the entire highway system.

3. Refurbish electrical systems, electronics, and mechanical systems to extend service lifeand improve safety. Rehabilitate or replace existing major drainage features to preserveoperational and structural integrity.

4. Stabilize known unstable slopes.

5. The program support subcategory consists of critical construction support items that arerequired to maintain efficiency and ensure continued progress of the construction programs.

Paraphrased excerpt from the State Highway System Plan, State Highway System Plan Service Objectives and Action Strategies.

Preservation ProgramFigure 325-3a

Highway Capital Preservation Program

P Preservation

P1 Roadway P3 Other FacilitiesP2 Structures

Paving

SafetyRestoration

Preservation

CatastrophicReduction

Rest Areas

WeighStations

UnstableSlopes

ProgramSupport

Major Drainage& Electrical

Design Manual Design Matrix ProceduresMay 2001 Metric Version Page 325-9

I Improvement

I1 Mobility — Improve mobility within congested highway corridors.

1. Mitigate congestion on urban highways in cooperation with local and regional jurisdictionswhen the peak period level of service falls below Level of Service D.

2. Provide uncongested condition (Level of Service C) on rural highways.

3. Provide bicycle connections along or across state highways within urban growth areas tocomplete local bicycle networks.

4. Complete the Freeway Core HOV Lane System in the Puget Sound region.

5. Provide uncongested conditions (Level of Service C) on high occupying vehicle (HOV) lanes.

I2 Safety — Provide the safest possible highways within available resources.

1. Improve highway sections that have a high accident history.

2. Improve geometrics of the Interstate System per the Federal Highway Administration(FHWA)/WSDOT Stewardship Agreement.

3. Improve roadways where geometrics, traffic volumes, and speed limits indicate a high accidentpotential.

4. Eliminate major at-grade intersections on multilane highways with speed limits of 45 mphor higher.

5. Construct intersection channelization, signals, or both when traffic volume warrants(thresholds) are met.

Paraphrased excerpt from the State Highway System Plan, State Highway System Plan Service Objectives and Action Strategies.

Improvement ProgramFigure 325-3b

Highway Capital Improvement Program

I Improvement

I1 Mobility

Urban

Rural

All Weather

Rest Areas

TrunkSystem

RestrictedBridges

UrbanBicycle

Core HOV

I2 Safety

BicycleTouring

CollisionReduction

CollisionPrevention

HALs

HACs

InterstateSafety Matrix

Risk

At-Grades

Signals &Channelization

I3 EconomicInitiatives

I4 EnvironmentalRetrofit

ScenicByways

Stormwater

Fish Barriers

NoiseReduction

Air Quality

PALs

Design Matrix Procedures Design ManualPage 325-10 Metric Version May 2001

I3 Economic Initiatives — Support efficient and reliable freight movement on state highways.Support tourism development and other Washington industries.

1. Upgrade state highways on the Freight and Goods Transportation System (FGTS) to have anall-weather surface capable of supporting legal loads year-round

2. Provide four-lane limited access facilities on a trunk system consisting of all FGTS highwayswith a T-1 classification (truck travel exceeding 10,000,000 tons per year).

3. Ensure public access to appropriately sized, rest room equipped facilities every 60 miles onthe NHS and Scenic & Recreational (S & R) highways.

4. Where cost effective, replace or modify structures on the Interstate System with restrictedvertical clearance.

5. Where cost effective, replace or modify structures that cannot carry legal overloads.

6. Cooperatively promote and interpret the heritage resources along S & R highways, includingproviding incentives for alternatives to outdoor advertising.

7. On rural bicycle touring routes, provide a minimum of 1.2 m shoulders (structures arenot included).

I4 Environmental Retrofit — Retrofit state highway facilities as appropriate to reduce existingenvironmental impacts.

1. Reconstruct storm water discharge facilities as opportunities arise.

2. Remove identified fish passage barriers.

3. Reduce the public’s exposure to noise from state highway facilities where local land useauthorities have adopted development regulations which reduce future exposure to excessivenoise levels near highway facilities.

4. Implement the WSDOT Transportation Control Measures required by the StatewideImplementation Plan for Air Quality.

Paraphrased excerpt from the State Highway System Plan, State Highway System Plan Service Objectives and Action Strategies

Improvement Program (continued)Figure 325-3c

Design Manual Design Matrix ProceduresMay 2001 Metric Version Page 325-11

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ap

ters

.

Design Manual Design Matrix ProceduresMay 2001 Metric Version Page 325-13

Des

ign

Mat

rix

3N

on

-In

ters

tate

Inte

rch

ang

e A

reas

Fig

ure

325

-6

� P

roje

ct

Typ

eB

RID

GE

SIN

TE

RS

EC

TIO

NS

BA

RR

IER

S

Desig

n E

lem

en

ts �

Hori

z.

Ali

gn.

Ver

t.

Ali

gn.

Lan

e

Wid

th

Shld

r

Wid

th

Lan

e &

Shld

r

Tap

er

Med

ian

Wid

th

Cro

ss

Slo

pe

Lan

e

Cro

ss

Slo

pe

Shld

r

On/O

ff

Conn.

Fil

l/

Dit

ch

Slo

pes

Acc

ess

(3)

Cle

ar

Zone

Sig

n.,

Del

.,

Illu

min

.

Bas

ic

Saf

ety

Lan

e

Wid

th

Shld

r

Wid

th

Ver

tica

l

Cle

ar-

ance

Str

uct

ura

l

Cap

acit

y

Turn

Rad

iiA

ngle

Sig

ht

Dis

t.

Ter

m. &

Tra

ns.

Sec

tion

(12

)

Std

Run

Bri

dge

Rai

l

Pre

serv

ati

on

Ro

ad

wa

y

(3-1

) N

on-I

nte

rsta

te F

reew

ay

DE

/FD

E/F

DE

/FD

E/F

DE

/FD

E/F

DE

/FD

E/F

DE

/FD

E/F

DE

/FB

BD

E/F

DE

/FF

BB

F

(3-2

) A

CP

/PC

CP

/BS

T O

verlays

DE

/MD

E/M

DE

/MD

E/M

DE

/FD

E/M

DE

/MD

E/M

DE

/FD

E/M

BB

DE

/MD

E/M

F

B

BB

F

(3-3

) R

epl.

AC

P w

/ P

CC

P a

t I/S

DE

/MD

E/M

EU

/ME

U/M

DE

/FD

E/M

EU

/MD

E/M

DE

/MB

BD

E/M

DE

/MF

BB

BF

Str

uc

ture

s

(3-4

) B

ridge R

epla

cem

ent

F (

2)

F (

2)

F (

2)

F (

2)

FF

(2)

F (

2)

F (

2)

F (

2)

F (

2)

FF

F (

2)

F (

2)

FF

(11)

F (

2)

F (

2)

FF

FF

(3-5

) B

ridge D

eck

R

ehab.

BB

FB

(6)

F

Imp

rovem

en

ts (

16)

Mo

bilit

y

(3-6

) N

on-I

nte

rsta

te F

reew

ay

FF

FF

FF

FF

FF

FF

FF

FF

F (

11)

FF

FF

FF

(3-7

) U

rban

F (

2)

F (

2)

F (

2)

F (

2)

FF

(2)

F (

2)

F (

2)

F (

2)

F (

2)

FF

FF

(2)

F (

2)

FF

(11)

F (

2)

F (

2)

FF

FF

(3-8

) R

ura

lF

(2)

F (

2)

F (

2)

F (

2)

FF

(2)

F (

2)

F (

2)

F (

2)

F (

2)

FF

FF

(2)

F (

2)

FF

(11)

F (

2)

F (

2)

FF

FF

(3-9

) H

OV

F (

2)

F (

2)

F (

2)

F (

2)

FF

(2)

F (

2)

F (

2)

F (

2)

F (

2)

FF

FF

(2)

F (

2)

FF

(11)

F (

2)

F (

2)

FF

FF

(3-1

0)

Bik

e/P

ed. C

onnect

ivity

(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)

Safe

ty

(3-1

1)

Non-I

nte

rsta

te F

reew

ay

FF

FF

FF

FF

FF

FF

FF

FF

FF

FF

FF

(3-1

2)

All

Oth

ers

(1)

M (

4)

M (

4)

M (

4)

M (

4)

FM

(4)

M (

4)

M (

4)

M (

4)

M (

4)

EU

/FF

FM

(4)

M (

4)

FM

(4)

M (

4)

FF

FF

Ec

on

om

ic D

ev

elo

pm

en

t

(3-1

3)

Fre

ight &

Goods

(Fro

st F

ree)

(8)

F (

2)

F (

2)

F (

2)

F (

2)

FF

(2)

F (

2)

F (

2)

F (

2)

F (

2)

EU

/FF

BD

E/F

DE

/FF

F (

11)

EU

/FE

U/F

EU

/FF

FF

(3-1

4)

4-L

ane T

runk

Sys

tem

FF

FF

FF

FF

FF

FF

FF

FF

F (

11)

FF

FF

FF

(3-1

5)

Rest A

reas (

New

)F

FF

FF

FF

FF

FF

FF

FF

FF

(11)

FF

FF

FF

(3-1

6)

Bridge R

est

rict

ions

F (

2)

F (

2)

F (

2)

F (

2)

FF

(2)

F (

2)

F (

2)

F (

2)

F (

2)

FF

F (

2)

F (

2)

FF

(11)

F (

2)

F (

2)

FF

FF

(3-1

7)

Bik

e R

oute

s (S

hld

rs)

EU

/M(7

)E

U/F

EU

/ME

U/M

BB

EU

/ME

U/M

FB

FB

EU

/F

N

ot A

pplic

able

(1)

C

olli

sion R

educt

ion (

HA

L, H

AC

, P

AL),

or

Colli

sion P

reve

ntio

n (

Ris

k, A

t G

rade R

em

ova

l, S

ignaliz

atio

n &

Channeliz

atio

n).

S

peci

fic d

efic

ienci

es

that

F F

ull

desi

gn le

vel

cr

eate

d the p

roje

ct m

ust

be u

pgra

ded to d

esi

gn le

vel a

s st

ate

d in

the m

atr

ix.

M M

odifi

ed desi

gn le

vel.

See C

hapte

r 430.

(2)

M

odifi

ed d

esi

gn le

vel m

ay

apply

base

d o

n a

corr

idor

or

pro

ject

analy

sis.

S

ee 3

25.0

2.

B B

asic

desig

n le

vel.

See C

hapte

r 410.

(3)

If d

esi

gnate

d in

Lim

ited A

ccess

Mast

er

Pla

n a

pply

lim

ited a

ccess

sta

ndard

s, if

not acc

ess

managem

ent st

andard

s apply

. S

ee C

hapte

r 920.

DE

D

esi

gn E

xceptio

n(4

) F

ull

desi

gn le

vel m

ay

apply

base

d o

n a

corr

idor

or

pro

ject

analy

sis.

See 3

25.0

2.

EU

E

valu

ate

Upgra

de

(5)

F

or

bik

e/p

edest

rian d

esi

gn s

ee C

hapte

rs 1

020 a

nd 1

025.

l

(6)

A

pplie

s only

to b

ridge e

nd term

inal a

nd tra

nsi

tion s

ect

ions.

(7)

1.2

m m

inim

um

should

ers

.

(8)

If all

weath

er

stru

cture

can b

e a

chie

ved w

ith s

pot dig

outs

and o

verlay,

Modifi

ed D

esi

gn L

eve

l Applie

s.

(11)

See C

hapte

r 1120.

(12)

Im

pact

attenuato

rs a

re c

onsi

dere

d a

s te

rmin

als

.

(16)

For

desi

gn e

lem

ents

not in

the m

atr

ix h

eadin

gs,

apply

full

desi

gn le

vel a

s fo

und in

the a

pplic

able

De

sig

n M

an

ua

l ch

apte

rs.

Design Matrix Procedures Design ManualPage 325-14 Metric Version May 2001

Des

ign

Mat

rix

4N

on

-In

ters

tate

Inte

rch

ang

e A

reas

Fig

ure

325

-7

� P

roje

ct

Ty

pe

Ra

mp

s a

nd

Co

lle

cto

r D

istr

ibu

tors

Cro

ss

R

oa

d

Ra

mp

Te

rmin

als

Ba

rrie

rsB

arr

iers

Des

ign

Ele

men

ts

�H

ori

z.

Alig

n.

Ve

rt.

Alig

n.

La

ne

W

idth

Sh

ldr

Wid

th

La

ne

&

Sh

ldr.

T

ap

er

On

/Off

C

on

n.

Cro

ss

Slo

pe

L

an

e

Cro

ss

Slo

pe

S

hld

r

Fill

/ D

itch

S

lop

es

Acce

ss

(3)

Cle

ar

Zo

ne

Sig

n,

De

l.,

Illu

min

.

Ba

sic

S

afe

ty

Turn

R

ad

iiA

ng

leI/

S S

igh

t D

ist.

Te

rm.

&

T

rans.

Se

ctio

n

(12

)

Std

R

un

Bri

dg

e

Ra

ilL

an

e

Wid

thS

hld

r W

idth

Ve

rt.

Cle

ar.

Pe

d.

&

Bik

eA

cce

ss

(3)

Sig

n.,

D

el.,

Illu

min

.

Fill

/ D

itch

S

lop

es

Cle

ar

Zo

ne

Ba

sic

S

afe

ty

Te

rm.

&

Tra

ns.

Se

ctio

n

(12

)

Std

.

Ru

nB

rid

ge

R

ail

Pre

se

rva

tio

nR

oa

dw

ay

(4-1

) N

on-I

nte

rsta

te F

reew

ay

DE

/FD

E/F

DE

/FD

E/F

DE

/FD

E/F

DE

/FD

E/F

DE

/FD

E/F

BB

DE

/FD

E/F

DE

/FB

BF

DE

/FD

E/F

FB

DE

/FB

BB

F

(4-2

) A

CP

/PC

CP

/BS

T

BB

BB

BF

FB

BB

BF

Ove

rla

ys R

am

ps

Str

uctu

res

(4-3

) B

rid

ge

Re

pla

ce

me

nt

F (

2)

F (

2)

F (

2)

F (

2)

FF

(2)

F (

2)

F (

2)

F (

2)

FF

FF

FF

FF

FF

(2)

F (

2)

FF

FF

F (

2)

FF

FF

(4-4

) B

rid

ge

De

ck R

eh

ab

B

BB

(6)

F

F

B

BB

(6)

F

Imp

rovem

en

ts

(16)

Mo

bil

ity

(4-5

) N

on-I

nte

rsta

te F

reew

ay

FF

FF

FF

FF

FF

FF

FF

FF

FF

FF

FF

FF

FF

FF

F

(4-6

) U

rban

F (

2)

F (

2)

F (

2)

F (

2)

FF

(2)

F (

2)

F (

2)

F (

2)

FF

FF

(2)

F (

2)

FF

FF

F (

2)

F (

2)

FF

FF

F (

2)

FF

FF

(4-7

) R

ura

lF

(2)

F (

2)

F (

2)

F (

2)

FF

(2)

F (

2)

F (

2)

F (

2)

FF

FF

(2)

F (

2)

FF

FF

F (

2)

F (

2)

FF

FF

F (

2)

FF

FF

(4-8

) H

OV

By P

ass

F (

2)

F (

2)

F (

2)

F (

2)

FF

(2)

F (

2)

F (

2)

F (

2)

FF

FF

(2)

F (

2)

FF

FF

F (

2)

F (

2)

FF

FF

F (

2)

FF

FF

(4-9

) B

ike

/Pe

d.

Co

nn

ectivity

(5)

(5)

(5)

(5)

(5)

(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)(5

)

(5)

(5)

(5)

(5)

(5)

Safe

ty

(4-1

0)

Non-I

nte

rsta

te F

reew

ay

FF

FF

FF

FF

FF

FF

FF

FF

FF

FF

FF

FF

FF

FF

(4-1

1)

At G

rade (

1)

F (

2)

F (

2)

F (

2)

F (

2)

FF

(2)

F (

2)

F (

2)

F (

2)

FF

FF

(2)

F (

2)

FF

FF

F (

2)

F (

2)

FF

FF

F (

2)

FF

FF

(4-1

2)

All

Oth

ers

(1

) M

(4)

M (

4)

M (

4)

M (

4)

FM

(4)

M (

4)

M (

4)

M (

4)

EU

/FF

FM

(4)

M (

4)

F

FF

FF

(2)

F (

2)

F

EU

/FF

M

(4)

FF

FF

Eco

no

mic

Develo

pm

en

t

(4-1

3)

Fo

ur-

La

ne

Tru

nk S

yste

mF

FF

FF

FF

FF

FF

FF

FF

FF

FF

FF

FF

FF

FF

F

No

t A

pp

lica

ble

(1)

C

olli

sio

n R

ed

uctio

n (

HA

L,

HA

C,

PA

L),

or

Co

llisio

n P

reve

ntio

n (

Ris

k,

Sig

na

liza

tio

n &

Ch

an

ne

liza

tio

n).

Sp

ecific

de

ficie

ncie

s t

ha

t

F

F

ull

de

sig

n le

ve

l

cre

ate

d t

he

pro

ject

mu

st

be

up

gra

de

d t

o d

esig

n le

ve

l a

s s

tate

d in

ma

trix

.

M

M

od

ifie

d

de

sig

n le

ve

l. S

ee

Ch

ap

ter

43

0.

(2)

M

od

ifie

d d

esig

n le

ve

l m

ay a

pp

ly b

ase

d o

n a

co

rrid

or

or

pro

ject

an

aly

sis

. S

ee

32

5.0

2.

B

B

asic

de

sig

n le

ve

l. S

ee

Ch

ap

ter

41

0.

(3)

If

de

sig

na

ted

in

lim

ite

d a

cce

ss m

aste

r p

lan

ap

ply

lim

ite

d a

cce

ss s

tan

da

rds,

if n

ot

acce

ss m

an

ag

em

en

t sta

nd

ard

s a

pp

ly.

Se

e C

ha

pte

r 9

20

.

DE

D

esig

n E

xce

ptio

n

(4)

F

ull

de

sig

n le

ve

l m

ay a

pp

ly b

ase

d o

n a

co

rrid

or

or

pro

ject

an

aly

sis

. S

ee

32

5.0

2.

EU

E

va

lua

te U

pg

rad

e

(5)

F

or

bik

e/p

ed

estr

ian

de

sig

n s

ee

s C

ha

pte

r 1

02

0 a

nd

10

25

.

l

(6)

A

pp

lies o

nly

to

bri

dg

e e

nd

te

rmin

als

an

d t

ran

sitio

n s

ectio

ns.

(7)

1

.2 m

min

imu

m s

ho

uld

ers

.

(12

) I

mp

act

att

en

ua

tors

are

co

nsid

ere

d a

s t

erm

ina

ls.

(16

) F

or

de

sig

n e

lem

en

ts n

ot

in t

he

ma

trix

he

ad

ing

s,

ap

ply

fu

ll d

esig

n le

ve

l a

s f

ou

nd

in

th

e a

pp

lica

ble

De

sig

n

Design Manual Design Matrix ProceduresMay 2001 Metric Version Page 325-15

Des

ign

Mat

rix

5N

on

-In

ters

tate

Inte

rch

ang

e A

reas

Fig

ure

325

-8

� P

roje

ct

Typ

e

B

rid

ges

Inte

rsecti

on

sB

arr

iers

De

sig

n E

lem

en

ts �

Horiz.

Alig

n.

Vert

.

Alig

n.

Lane

Wid

th

Shld

r

Wid

th

Lane &

Shld

r

Taper

Media

n

Wid

th

Cro

ss

Slo

pe

Lane

Cro

ss

Slo

pe

Shld

r

Fill

/

Ditch

Slo

pes

Acce

ss

(3)

Cle

ar

Zone

Sig

n,

Del.,

Illum

in.

Ba

sic

Safe

ty

Lane

Wid

th

Shld

r

Wid

th

Vert

ical

Cle

ar.

Str

uctu

ral

Capacity

Turn

Radii

Angle

Sig

ht

Dis

t.

Term

. &

Tra

ns.

Sectio

n

(12

)

Std

Run

Bridge

Rail

Pre

serv

ati

on

Ro

ad

way

(5-1

) A

CP

/PC

CP

BB

F

BB

BF

(5-2

) B

ST

(5-3

) B

ST

Route

s/B

asi

c S

afe

tyB

B

BB

BF

(5-4

) R

epla

ce A

CP

with

PC

CP

at I/S

EU

/ME

U/M

EU

/ME

U/M

BB

FB

BF

Str

uctu

res

(5-5

) B

ridge R

epla

cem

ent

M

F

M

M

FM

M

M

F

FF

(2

)F

(2

)F

F (

11

)M

M

FF

FF

(5-6

) B

ridge R

epl.

(Multi

-Lane)

F (

2)

F (

2)

F (

2)

F (

2)

FF

(2

)F

(2

)F

(2

)F

(2

)F

F

F (

2)

F (

2)

FF

(1

1)

F (

2)

F (

2)

F

FF

F(5

-7)

Bridge D

eck R

ehab

BB

B (

6)

FF

Imp

rovem

en

ts (

16

)

Mo

bilit

y

(5-8

) U

rban (

Multi

lane)

F (

2)

F (

2)

F (

2)

F (

2)

FF

(2

)F

(2

)F

(2

)F

(2

)F

FF

F (

2)

F (

2)

FF

(1

1)

EU

/FE

U/F

FF

FF

(5-9

) U

rban

MM

MM

FM

MM

FF

FM

MF

F (

11

)E

U/M

EU

/MF

FF

F

(5-1

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Design Manual Design Documentation, Approval, and Process ReviewMay 2001 Metric Version Page 330-1

Design Documentation,330 Approval, and Process Review

Highway Runoff Manual, WSDOT

Executive Order E 1010.00, “Certification ofDocuments by Licensed Professionals,” WSDOT

330.03 PurposeDesign documentation is prepared to record theevaluations by the various disciplines that resultin design recommendations. Design assumptionsand decisions made prior to and during theproject definition phase are included. Changesthat occur throughout the project developmentprocess are documented. Justification andapprovals, if required, are also included.

The design documentation identifies:

• The condition or problem that generated thepurpose and need for the project (as noted inthe Project Summary)

• The design alternatives considered

• The project design selected

• The work required to satisfy the commit-ments made in the environmental documents

• The conformity of the selected design todepartmental policies and standard practices

• The supporting information for any designvariances

• The internal and external coordination

The design documentation is used to:

• Examine estimates of cost

• Prepare access and right of way plans

• Assure that all commitments are provided forin the recommended design

• Plan for maintenance responsibilities as aresult of the project

• Provide supporting information for designvariances

• Explain design decisions

• Document the project development processand design decisions

330.01 General330.02 References330.03 Purpose330.04 Project Development330.05 Project Definition Phase330.06 Design Documentation330.07 Design Approval330.08 Process Review

330.01 GeneralThe project file contains the documentationof planning, project definition, programming,design, approvals, contract assembly, utilityrelocation, needed right-of-way, advertisement,award, construction, and maintenance of aproject. A project file is completed for allproject and follows the project until a newproject supersedes it.

Design documentation is a part of the project file.It documents design decisions and the designprocess followed. Design documentation isretained in a permanent retrievable file at acentral location in each region. For operationalchanges and developer projects, design documen-tation is required and is retained by the region.

330.02 ReferencesConstruction Manual, M 41-01, WSDOT

Directional Documents Publication Index,D 00-00, WSDOT

Washington State Department of TransportationCertification Acceptance Approval from FHWA,December 4, 1978, and subsequent revisions

FHWA Washington Stewardship Plan, WSDOT1993

Master Plan for Limited Access, WSDOT

Advertisement and Award Manual, M 27-02,WSDOT

Plans Preparation Manual, M 22-31, WSDOT

Route Development Plan, WSDOT

State Highway System Plan, WSDOT

Design Documentation, Approval, and Process Review Design ManualPage 330-2 Metric Version May 2001

• Preserve a record of the project’sdevelopment for future reference

• Prepare plans, specifications, and estimate(PS&E)

330.04 Project DevelopmentThe region initiates the project by preparingthe Project Summary package. The projectcoordination with other disciplines (such asReal Estate Services, Utilities, and Surveying)is started in the project definition phase andcontinues throughout the project’s development.The region coordinates with state and federalresource agencies and local governments toprovide and obtain information to assist indeveloping the project.

The project is developed in accordance with allapplicable Directives, Instructional Letters, andmanuals as listed in D 00-00; the Master Plan forLimited Access Highways; State Highway SystemPlan; Level of Development Plan; Route Devel-opment Plan; FHWA Washington StewardshipPlan; and the Project Summary.

The region develops and maintains documen-tation for each project. This file includesdocumentation of all work on the project frombefore the project definition phase through publicinvolvement, environmental action, designdecisions, right of way acquisition, and PS&Edevelopment. Refer to the Plans PreparationManual for PS&E documentation.

All projects involving FHWA action requireNEPA clearance. Environmental action is deter-mined through the Environmental ClassificationSummary (ECS) form. The environmentalapproval levels are shown in Figure 330-2.

Upon receipt of the ECS approval, the regionproceeds with environmental documentation,including instituting public involvement methodsthat are appropriate to the magnitude and type ofthe project. (See Chapter 210.)

The Assistant State Design Engineer works withthe regions on project development and conductsprocess reviews on projects as described in330.08.

330.05 Project Definition PhaseProject definition is the initial phase of projectdevelopment. The project definition effort isprompted by the State Highway System Plan. Theproject definition phase consists of determining apreliminary project description, schedule, andestimate. The intent is to make design decisionsearly in the project development process. Duringthe project definition effort, the Project Summarydocuments are produced.

Project Summary provides information on theresults of the project definition phase; links theproject to the Highway System Plan; and docu-ments the design decisions, the environmentalclassification, and agency coordination. TheProject Summary is developed before the projectis funded for construction. The Project Summaryconsists of the Environmental Review Summary,Design Decisions Summary, and ProjectDefinition.

Environmental Review Summary (ERS) liststhe environmental permits and approvals that willbe required, environmental classifications, andenvironmental considerations. This form listsrequirements by environmental and permittingagencies. If there is a change in project definition,the information in the ERS must be reviewed andchanged to match the new project definition. TheERS is prepared during the project definitioneffort. The ERS is approved by the region.

Design Decisions Summary (DDS) states theroadway geometrics, design deviations, evaluateupgrades (EUs), other roadway features, andany design decisions made during the projectdefinition phase of a project. The informationcontained in this form is compiled from variousdatabases of departmental information, field datacollection, and evaluations made in developmentof the Project Definition and the ERS. To signthe Design Decisions Summary, the region mustbe comfortable that there will be no significantchange in the project definition or estimated cost.Design decisions may be revised throughout theproject development process based on continuingevaluations.

Design Manual Design Documentation, Approval, and Process ReviewMay 2001 Metric Version Page 330-3

The DDS is approved by the Assistant StateDesign Engineer for new construction andreconstruction projects on the Interstate System.The regional design authority approves the DDSfor all other types of projects. (See Figure 330-1)

Project Definition (PD) identifies the variousdisciplines and design elements that will beencountered in project development. The ProjectDefinition states the needs, the purpose of theproject, program categories, and the designmatrices that were used to develop the ProjectDefinition. This information determines the levelof documentation and evaluation that is neededfor approval of the design. The Project Summaryis completed in the project definition phase.

Once the project has been formally adopted intothe WSDOT operating program, project develop-ment continues. Design of projects is furtherrefined by a project manager through an interdis-ciplinary team process. Projects continue with thedevelopment of environmental and designdocumentation.

330.06 Design Documentation(1) FHWA RequirementsFor projects on the Interstate System, the levelof FHWA oversight varies according to the typeof project, the agency doing the work, and thefunding source. See Figure 330-1 for details.

FHWA operational acceptance is required forany new or revised access point on the InterstateSystem, regardless of funding. (See Chapter1425.)

Documentation for projects requiring FHWAreview and approval is submitted through theOlympia Service Center (OSC) Design Office.Include the following items if applicable tothe project:

• Project Definition (form) (PD)

• Environmental Review Summary (form)(ERS)

• Design Decisions Summary (form) (DDS)

• Design Variance Inventory (form) withsupport information for EUs and deviations

• Cost estimate

• NEPA documentation

• Design Clear Zone Inventory (form)

• Interchange plans, and profiles (and roadwaysections if appropriate)

• Traffic projections and analysis

• Accident analysis

• The report requesting new or revised accesspoints

The forms listed above (Project Definition,Environmental Review Summary, DesignDecisions Summary) are generated by the ProjectSummary database. Specific on-line instructionsfor filling them out are contained in the database.

(2) Design DocumentsThe design portion of the project file preservesthe decision documents generated during thedesign process. A summary (list) of these docu-ments is recommended because projects vary inscope and the documents applicable to the projectvary accordingly.

The design documents commonly included in theproject file for all but the simplest projects arelisted below. The ERS, PD, and DDS forms arein the Project Summary database which includeson-line instructions.

• Documentation of any design decision to domore, or less, than WSDOT guidance indi-cates and documentation of design decisionsfor components not addressed by WSDOTguidance. (These may be separate documentsor portions of the documents listed below.)

• Environmental Review Summary (ERS form)

• Project Definition (PD form)

• Design Decisions Summary (DDS form)

• Corridor or project analysis. See Chapter 325for definition and Figures 330-5a and 5b.

• Design Variance Inventory (form) withsupport information for EUs and deviations

• Cost Estimate

• Design Clear Zone Inventory (form)

Design Documentation, Approval, and Process Review Design ManualPage 330-4 Metric Version May 2001

• Copies of interchange plans, intersectionplans, and profiles (and roadway sectionsif appropriate)

• Right of way plans

• Monumentation Map

• SEPA and NEPA documentation

• Work Zone Traffic Control Strategy

• Other project components: Provide docu-mentation in the project file as detailed inthe applicable Design Manual chapters.Documentation is not required for compo-nents not related to the project.

The Design Variance Inventory is required forNHS roadway preservation projects only. Thisform lists all design exceptions, evaluateupgrades not upgraded to the applicable designlevel, and deviations.

The Project Definition and EnvironmentalReview Summary are required for all projects.

The Design Decisions Summary form is notrequired for the following project types unlessthey involve reconstructing the lanes, shoulders,or fill slopes. Since these project types are notincluded in the design matrices, evaluate themwith respect to modified design level (M) fornon-NHS routes and full design level (F) forall others.

• Bridge painting

• Crushing and stockpiling

• Pit site reclamation

• Lane marker replacement

• Guide post replacement

• Signal rephasing

• Signal upgrade

• Seismic retrofit

• Bridge joint repair

• Navigation light replacement

• Signing upgrade

• Illumination Upgrade

• Rumble Strips

• Electrical upgrades

• Major Drainage

• Slope Stability*

• Bridge scour

• Fish passage

• Other projects as approved by OSC Design

*Address rock scour within the project limitswhenever feasible.

(3) Certification of Documents byLicensed ProfessionalsAll original technical documents must bear thecertification of the responsible licensee. SeeExecutive Order E 1010.00.

(4) Deviation and Evaluate UpgradeDocumentationThe Design Variance Inventory (a form), DE,EU, and deviations are introduced in Chapter325.

To prepare a deviation request, or document anEU, use the list in Figure 330-6 as a general guidefor the sequence of the content. The list is not all-inclusive of potential content and it might includesuggested topics that do not apply to a particularproject. Each deviation request will be unique.Sample deviations and EUs are on the Internet atwww.wsdot.wa.gov/eesc/CAE/pse/

Documentation of a deviation must containjustification and must be approved at the appro-priate administrative level as shown in Figure330-1. When applying for deviation approval,it is necessary to provide two explanations. Thefirst explains why the WSDOT guidance wasnot or cannot be used. The second providesthe justification for the design that is proposed.Justification for a deviation must be supportedby at least two of the following:

• Accident history or potential

• Benefit/cost analysis

• Engineering judgment

• Environmental issues

• Route continuity

Design Manual Design Documentation, Approval, and Process ReviewMay 2001 Metric Version Page 330-5

An element of engineering judgment might bereferences to other publications.

Once a deviation is approved, it applies to thatproject only. When a new project is programmedat the same location, the subject design elementmust be reevaluated and either (1) the subjectdesign element is rebuilt to meet or exceed theapplicable design level, or (2) a new, approveddeviation is preserved in the design file for thenew project.

330.07 Design ApprovalDesign Approval is the approval of the designfile. When the design file is complete, the regiontakes an action to make an approval that becomespart of the file. Figure 330-1 identifies theapproval levels for design, evaluate upgrades(EUs), and deviations. The following items mustbe approved prior to design approval:

• Required environmental documentation(NEPA, SEPA)

• Project Summary (includes ProjectDefinition, Design Decisions Summary,and Environmental Review Summary)

• Design Variance Inventory form (includesevaluate upgrades and deviations) for NHS,deviations and EUs for non-NHS

• Cost estimate

See Figures 330-1 through 4 for review andapproval levels for project design and PS&Edocuments. Figures 330-2, 330-3, and 330-4are summaries of information provided in otherWSDOT documents.

330.08 Process ReviewThe process review is done to provide reasonableassurance that projects are prepared in compli-ance with established standards and proceduresand that adequate records exist to show compli-ance with state and federal requirements.

The design and PS&E process review is per-formed in each region at least once each yearby the OSC Project Development Branch. Fourdocuments are used in the review process: theDesign Review Check List, PS&E ReviewCheck List, Design Review Summary, and

PS&E Review Summary. These are genericforms used for all project reviews. Copies ofthese working documents are available forreference when assembling project documenta-tion. OSC Design Office, Project Developmentmaintains current copies on Exchange. For papercopies or a specific electronic address contactthe OSC Project Development Branch.

Each project selected for review is examinedcompletely and systematically beginning with theproject definition and the project summary phaseand continuing through contract plans and (whenavailable) construction records and changeorders. Projects are normally selected aftercontract award. For projects having major trafficdesign elements, the OSC Traffic Operationspersonnel are involved in the review. TheWSDOT process reviews may be held inconjunction with FHWA process reviews.

The OSC Project Development Branch schedulesthe process review and coordinates it with theregion. Notification of the scheduled processreview is sent to FHWA for their information andfor use in coordinating a joint process review.

A process review follows this general agenda:

1. Review team meets with regional personnelto discuss the object of the review.

2. Review team reviews the design and PS&Edocuments, and the construction documentsand change orders if available, using thecheck lists.

3. Review team meets with regional personnelto ask questions and clarify issues that havearisen.

4. Review team meets with regional personnelto discuss findings.

5. Review team submits a draft report to theregion for comments and input.

6. If the review of a project shows a seriousdiscrepancy, the regional design authority isasked to report the steps that will be taken tocorrect the deficiency.

7. The process review summary forms arecompleted.

Design Documentation, Approval, and Process Review Design ManualPage 330-6 Metric Version May 2001

8. The summary forms and check lists areevaluated by the State Design Engineer.

9. The findings and recommendations of theState Design Engineer are forwarded to theregional design authority, for action and/orinformation, within 30 days of the review.

P65:DP/DMM

Design Manual Design Documentation, Approval, and Process ReviewMay 2001 Metric Version Page 330-7

Design Approval LevelFigure 330-1

FHWA Deviation andOversight Corridor/Project Design

Project Design Level Approval(f) EU Approval Approval

Interstate

New/Reconstruction(e) FHWA Region FHWA• Federal funds (a)• No federal funds (b)

Intelligent Transportation (c) OSC Design Region OSC DesignSystem (ITS) over$1 million

All Other(d) OSC Design Region Region• Federal funds (c)• State funds (c)• Local agency funds (b)

NHS

All (c) OSC Design Region Region

Non-NHS

New/Reconstruction N/A OSC Design Region Region

All Other N/A Region Region Region

FHWA = Federal Highway AdministrationOSC = Olympia Service Center

(a) Requires FHWA review and approval (full oversight) of design and PS&E submitted by OSC Design.

(b) To determine the appropriate oversight level, FHWA reviews the Project Summary (or otherprogramming document) submitted by OSC Design or by TransAid through OSC Design.

(c) FHWA oversight is accomplished by process review. (See 330.08.)

(d) Reduction of through lane or shoulder widths (regardless of funding) requires FHWA review andapproval of the proposal.

(e) See Chapter 325 for definition.

(f) These approval levels also apply to deviation processing for local agency work on a state highway.

Design Documentation, Approval, and Process Review Design ManualPage 330-8 Metric Version May 2001

Region OSC FHWA

Item Review Approval Review Approval Review Approval

Program Development

Work Order Authorization X X [1]

Public Hearings

Corridor Plan [13] X

Design Summary [14] X

Access Hearing Plan [14] X

Access Findings and Order [15] X

Environmental By Classification

Summary (ECS) NEPA X

Class l NEPA (EIS) X X

Class l SEPA (EIS) X

Class ll NEPA X*Programmatical Categorical Exclusion (CE)

Class ll NEPA — DocumentedCategorical Exclusion (CE) X X

Class ll SEPA —Categorical Exemption (CE) X

Class lll NEPA — XEnvironmental Assessment (EA) X

SEPA Check List X

*If on the preapproved list.

Notes:X Normal procedure[1] Federal aid projects only[3] Applies to new/reconstruction projects on Interstate routes[13] Assistant Secretary for Environmental and Engineering Service Center approval[14] State Design Engineer approval[15] Refer to Chapter 210 for approval requirements

Reviews and ApprovalsFigure 330-2

Design Manual Design Documentation, Approval, and Process ReviewMay 2001 Metric Version Page 330-9

Reviews and Approvals, DesignFigure 330-3a

Region OSC FHWA

Item R Approval Review Approval Review Approval

Design

Design Deviations [2] [2] [2]

Experimental Features X X [3]

Environmental Review Summary X

Final Design Decisions Summary X X [3]

Final Project Definition X [4]

Access Point Decision Report X X

Non-Interstate Interchange AccessPoint Report X

Interchange Plans [12] X X [3]

Intersection Plans [12] X X [3]

Right of Way Plans [13] X

Monumentation Map X

Materials Source Report X [5]

Pavement Determination Report X [5]

Project Design Approval [2] [2] [2]

Resurfacing Report X [5]

Signal Permits X [6]

Geotechnical Report X [5]

Tied Bids X X [3]

Bridge Design Plans (Bridge Layout) X X

Hydraulic Report [7] X [8]

Preliminary Signalization Plans X

Rest Area Plans X

Roadside Restoration Plans X [9] X [10]

Structures Requiring TS&L’s X X

Wetland Mitigation Plans X X

Wetland Mitigation Planting Plans X [9][11] X [10]

Grading Plans X [9][11] X [10]

Design Documentation, Approval, and Process Review Design ManualPage 330-10 Metric Version May 2001

Notes:X Normal procedure[2] Refer to Figure 330-1 for design approval level[3] Applies to new/reconstruction projects on Interstate routes[4] OSC Program Management[5] Submit to OSC Materials Branch for review and approval[6] Approved by Regional Administrator[7] See M 23-03, Hydraulics Manual for additional guidance[8] Region to submit Hydraulic Report. Refer to Hydraulics Manual[9] Applies only to regions with a Landscape Architect[10] Applies only to regions without a Landscape Architect[11] Approved by Regional Landscape Architect[12] Include channelization details[13] Certified by the responsible professional licensee

Reviews and Approvals, Design (continued)Figure 330-3b

Design Manual Design Documentation, Approval, and Process ReviewMay 2001 Metric Version Page 330-11

PS&E Process ApprovalsFigure 330-4

InterstateNew/ NHS and

Item Reconstruction Non-NHS

Minority/training goals* ** OSC(a) OSC(a)

Right of way certification for federal aid projects OSC(b) OSC(b)

Right of way certification for state funded projects Region(b) Region(b)

Railroad agreements OSC(c) OSC(c)

Work performed for public or private entities* OSC[1][5] Region[1][5]

State force work* FHWA[2](d) OSC[2](c)(d)

Use of state furnished stockpiled materials* FHWA[3] Region[3]

Stockpiling materials for future projects* FHWA[3] Region[3]

Work order authorization OSC[4](d) OSC[4](d)

Ultimate reclamation plan approval through DNR Region Region

Proprietary item use* FHWA[3] OSC[5](c)

Mandatory material sources and/or waste sites* FHWA[3] Region[3]

Nonstandard bid item use* Region Region

Incentive provisions FHWA OSC(e)

Nonstandard time for completion liquidated FHWA(e) OSC(e)damages*

Interim liquidated damages* OSC(f) OSC(f)

Notes:[1] This work requires a written agreement.[2] Use of state forces is subject to $50,000 limitation as stipulated in RCWs 47.28.030 and 47.28.035.[3] Applies only to federal aid projects. However, document for all projects.[4] Prior FHWA funding approval required for federal aid projects.[5] Region approval subject to $250,000 limitation.

Regional or Olympia Service Center References:approval authority: *Plans Preparation Manual(a) Office of Equal Opportunity **Advertisement and Award Manual(b) Real Estate Services(c) Design Office(d) Program Management Office(e) Construction Office(f) Transportation Data Office

Design Documentation, Approval, and Process Review Design ManualPage 330-12 Metric Version May 2001

Sample Project AnalysisFigure 330-5a

Project Analysis

L-0000 SR A

Yodelin Hill Climbing Lane SR A MP B to MP C

Overview

High truck volumes and steep grades are adversely impacting traffic flows and safety onthis section of highway. The purpose of this project is to increase traffic flows and safetyby adding a climbing lane.

For this NHS rural mobility project, the Design Matrix calls for full design level with anoption to use modified design level based on a corridor or project analysis. In DesignManual Chapter 440, the ADT of 6300, DHV of 730, and truck percentage of 18% indesign year 2016 indicates design class P-2 multilane. Considering the followingjustification, the region proposes to design this project to the modified design levelMDL-14 with a truck climbing lane.

A climbing lane warrant has been met.

Route Description

This section of SR A parallels a mountain stream and is located in steep mountainousterrain. Adjacent roadway sections consist of two 3.4 m lanes with 1.2 m shoulders.Fill slopes generally range between 1:3 and 1:4 as do ditch inslopes. The posted speed is60 mph in both directions.

Comparison

Existing Modified Design Full Design ProposedConditions Level (MDL-14) Level (P-2) (MDL-14)

Fill slopes 1:3 to 1:4 1:4 1:6 1:4

Lane Width 3.4 3.6 3.6 3.6

No. Thru. Lanes 2 2+1 4 2+1

Shoulder Width 1.2 1.2 3.0 1.2

Median Width none none 18 none

The use of full design level would require a wider roadway which would in turn requiresignificant impacts to the stream, very high and lengthy rock cut, additional right of wayincluding acquisition of numerous cabins, and utility impacts. The cost to construct thissection to full design level is approximately $6 million more than to construct to modifieddesign level with an additional climbing lane.

Adding a fourth lane throughout this narrow corridor would have minimal benefits to thetraveling public. There is no proposed improvement in the 20 year System Plan to makeeither this section, or adjacent sections of highway, four lanes.

Design Manual Design Documentation, Approval, and Process ReviewMay 2001 Metric Version Page 330-13

Accidents

The accident history from April 1993 through March 1996 indicates 28 accidents resultingin 1 fatality, 16 injuries, and $392,100 in property damage.

14 of the 28 accidents, including the fatality, occurred while passing uphill traffic. Sevenother accidents occurred during turning maneuvers at four different locations throughoutthe project.

Addition of the truck climbing lane should reduce the number and severity of accidents onthis section of roadway. The additional fourth lane throughout would probably notsignificantly reduce the number or severity of accidents.

Summary

Considering route continuity, environmental constrains, additional cost, and minimalbenefit, the region feels constructing to full design level is not justified. Therefore, theregion proposes to construct this project to modified design level.

___________________ __________ ___________________ __________Regional Concurrence Date OSC Design Approval Date

Sample Project AnalysisFigure 330-5b

Design Documentation, Approval, and Process Review Design ManualPage 330-14 Metric Version May 2001

Deviation and Evaluate Upgrade Request/Documentation Content ListFigure 330-6

1. Overview

(a) The safety or improvement need that the project is to meet

(b) Description of the project as a whole

(c) Highway classification and applicable Design Matrix

(d) Funding sources

(e) Evidence of deviations approved for previous projects (same location)

2. Design Alternatives in Question

(a) Existing Conditions and Design Data

• Location in question• Rural, urban, or developing• Route development plan• Environmental issues• Right of way issues• Number of lanes and existing geometrics• Present and 20 year projected ADT• Speed limit and operating speed• Percentage of trucks

(b) Accident Summary and Analysis

(c) Design Using the Design Manual Guidance

• Description• Cost estimate• B/C ratio• Advantages and disadvantages• Reasons for considering other designs

(d) Other Alternatives

• Description• Cost estimate• B/C ratio• Advantages and disadvantages• Reasons for rejection

(e) Selected design requiring documentation as a deviation(or justification to file)

• Description• Cost estimate• B/C ratio• Advantages and disadvantages• Justification - see 330.06(4)

3. Concurrences, Approvals, and Professional Seals

410 Basic Design Level

410.01 General410.02 Required Basic Safety Items of Work410.03 Minor Safety and Minor Preservation

Work

410.01 GeneralBasic design level (B) preserves pavementstructures, extends pavement service life, andmaintains safe operations of the highway. Thebasic design level includes restoring the roadwayfor safe operations and, where needed, mayinclude safety enhancement. Flexibility is pro-vided so that other conditions can be enhancedwhile remaining within the scope of pavementpreservation work.

The required safety items of work listed belowmay be programmed under a separate projectfrom the paving project as long as there is somebenefit to the delay, the safety features remainfunctional, and the work is completed within twoyears after the completion of the paving project.If some of the required items are separated fromthe paving project, maintain a separate documen-tation file that addresses the separation of workduring the two-year time period.

For bituminous surface treatment projects onnon-NHS routes, the separation of required safetyitems is not limited to the two years stated above.The safety work can be accomplished separatelyusing a corridor-by-corridor approach.

410.02 Required Basic SafetyItems of WorkFor basic design level (B), the following items ofwork are required:

• Install and replace delineation in accordancewith Chapter 830

• Install and replace rumble strips in accor-dance with the matrices and Chapter 700

• Adjust existing features that are affected byresurfacing, such as monuments, catchbasins, and access covers

• Adjust guardrail height in accordance withChapter 710

• Replace deficient signing, as needed, usingcurrent standards. This does not includereplacement of sign bridges or cantileversupports

• Relocate, protect, or provide breakawayfeatures for sign supports, luminaires, andWSDOT electrical service poles inside thedesign clear zone

• Restore sight distance at public road intersec-tions and the inside of curves through lowcost measures if they are available such asremoval or relocation of signs and otherobstructions, and cutting of vegetative matter

• Upgrade nonstandard bridge rail in accor-dance with the matrices and Chapter 710

• Upgrade barrier terminals and bridge endprotection, including transitions, in accor-dance with Chapter 710

• Restore the cross slope to 1.5 percent whenthe existing cross slope is flatter than1.5 percent and, in the engineer’s judgment,the steeper slope is needed to solve highwayrunoff problems in areas of intense rainfall

410.03 Minor Safety and MinorPreservation WorkConsider the following items, where appropriate,within the limits of a paving project:

• Spot safety enhancements. These aremodifications to isolated roadway orroadside features that, in the engineer’sjudgment, reduce potential accidentfrequency or severity

• Striping changes that will provide additionalor improved channelization for intersectionswhere sufficient pavement width andstructural adequacy exist

• Roadside safety hardware (such as guardrail,signposts, impact attenuators)

Design Manual Basic Design LevelMay 2001 Metric Version Page 410-1

• Addressing Location 1 Utility Objects inaccordance with the Utilities AccommodationPolicy, M 22-86

Consider the following items when restoration,replacement, or completion is necessary to assurethat an existing system can function as intended:

• Right of way fencing

• Drainage

• Illumination

• Electrical

Examples of the above include, but are notlimited to, the following: installing short sectionsof fence needed to control access, replacinggrates that are a hazard to bicycles, upgradingelectrical system components that requireexcessive maintenance, and beveling culverts.

P65:DMM

Basic Design Level Design ManualPage 410-2 Metric Version May 2001

Design Manual Modified Design LevelMay 2001 Metric Version Page 430-1

430 Modified Design Level

430.03 Roadway WidthsThe design of a project must not decrease theexisting roadway width.

Lane and shoulder widths are shown in Figures430-3 and 4. Consider joint use with other modesof transportation in shoulder design.

Review route continuity and roadway widths.Select widths on the tangents to be consistentthroughout a given section of the route. Make anychanges where the route characteristics change.

(1) Turning Roadway WidthsIt may be necessary to widen the roadway oncurves to accommodate large vehicles. The totaltwo-lane roadway width of a curve may not beless than that shown in Figure 430-5 or, if theinternal angle (delta) is less than 90 degrees,Figure 430-6. The proposed roadway width fora curve may not be less than that of the adjacenttangent sections.

The total roadway width from Figure 430-5 orFigure 430-6 may include the shoulder. Whenthe shoulder is included, full-depth pavementis required.

Widening of the total roadway width of a curveby less than 0.6 m is not required for existingtwo-lane roadways that are to remain in place.

(2) Median WidthSee Figure 430-3.

430.04 Ramp Lane WidthsRamp lane widths are shown in Figure 430-1 andin Figure 430-10. For ramps with radii less than100 m apply full design level see Chapter 640.

Curve Radius Lane Width

Tangent - 1200 m 3.9 m

900 m - 600 m 4.2 m

300 m - 100 m 4.5 m

Turning Ramp Lane WidthsModified Design Level

Figure 430-1

430.01 General430.02 Design Speed430.03 Roadway Widths430.04 Ramp Lane Widths430.05 Stopping Sight Distance430.06 Profile Grades430.07 Cross Slope430.08 Fill Slopes and Ditch Inslopes430.09 Intersections430.10 Bridges430.11 Documentation

430.01 GeneralModified design level (M) preserves andimproves existing roadway geometrics, safety,and operational elements. This chapter providesthe design guidance that is unique to the modifieddesign level.

Design elements that do not have modified designlevel guidance include:

• Access control, see Chapter 1420• Access management, see Chapter 920• Basic safety, see Chapter 410• Clear zone, see Chapter 700• Traffic barriers, see Chapter 710• Gore area lighting, see Chapter 840• Interchange areas, see Chapter 940

Design elements that have both modified and fulldesign level components include:

• Horizontal alignment, see Chapter 620• Superelevation and shoulder cross slope,

see Chapter 640• Vertical alignment, see Chapter 630

430.02 Design SpeedWhen applying modified design level to aproject, select a design speed for use in the designprocess that reflects the character of the terrainand the type of highway. Select a speed that isnot less than the posted speed, the proposedposted speed, or the operating speed, whicheveris higher. Document which speed was used,include any supporting studies and data.

Modified Design Level Design ManualPage 430-2 Metric Version May 2001

430.05 Stopping Sight Distance(1) Existing Stopping Sight Distancefor Vertical CurvesFor crest vertical curves use the existing algebraicdifference in grades and the length of curve tocompare the existing condition to Figure 430-7.If corrective action is required by Figure 430-7,apply full design level and see Chapter 650.

When modified design level is being applied, sagvertical curves are not normally addressed.

(2) Stopping Sight Distance forHorizontal CurvesFor modified design level, use the existing lateralclearance to the sight obstruction and the curveradius to compare the existing condition toFigure 430-8. If corrective action is requiredby Figure 430-8, apply full design level and seeChapter 650.

For Figure 430-8, an obstruction is any objectwith a height of 0.6 m or more above the roadwaysurface on the inside of a curve. Examples ofpossible obstructions are median barrier, guard-rail, bridges, walls, cut slopes, wooded areas,and buildings.

430.06 Profile GradesWhen applying modified design level, profilegrades generally are not flattened. However,corrective action may be justified for combina-tions of steep grades and restricted horizontal orvertical curvature. Identify major modificationsto horizontal and vertical alignment in the ProjectDecisions Summary. Total removal of pavementand reconstruction of the subgrade are examplesof major modifications.

430.07 Cross SlopeOn all tangent sections, the normal cross slopesof the traveled way are 2 percent. Cross slopes upto 2 percent have a barely perceptible effect onvehicle steering, but cross slopes steeper than2 percent can be noticeable.

The algebraic difference in cross slopes is anoperational factor during a passing maneuveron a two-lane road. Its influence increases whenincreased traffic volumes decrease the numberand size of available passing opportunities.

If a longitudinal contiguous section of pavementis to be removed or is on a reconstructed align-ment, or if a top course is to be placed overexisting pavement, design the restored pavementto a cross slope of 2 percent.

A somewhat steeper cross slope may be neces-sary to facilitate pavement drainage in areas ofintense rainfall, even though this might be lessdesirable from the operational point of view.In such areas, the design cross slopes may beincreased to 2.5 percent with an algebraicdifference of 5 percent.

For existing pavements, cross slopes within arange of 1 to 3 percent may remain if there areno operational or drainage problems and— ona two-way, two-lane road — the followingconditions are met:

• The algebraic difference is not greater than4 percent where the ADT is greater than2000.

• The algebraic difference is not greater than5 percent where the ADT is 2000 or less.

• The algebraic difference is not greater than6 percent and the road is striped or signed forno passing.

If the existing pavement does not meet theconditions above, correct the cross slope(s) tobe within the range of 1.5 to 2.5 percent. For atwo-way, two-lane road, provide an algebraicdifference to meet the appropriate conditionsstated above except when facilitating drainagein areas of intense rainfall. When applyingmodified design level to a road with bituminoussurface treatment (BST), cross slope correctionis not required on the basis of algebraicdifferences alone.

To maintain or restore curb height, considerlowering the existing pavement level and correct-ing cross slope by grinding before an asphaltoverlay. On urban highways, the cross slope ofthe outside shoulder may be steepened to mini-mize curb height and other related impacts. Theshoulder may be up to 6 percent with a rolloverbetween the traveled way and the shoulder of nomore than 8 percent.

Design Manual Modified Design LevelMay 2001 Metric Version Page 430-3

430.08 Fill Slopes and DitchInslopesForeslopes (fill slopes and ditch inslopes) and cutslopes are designed as shown in Figure 430-9 formodified design level main line roadway sec-tions. After the foreslope has been determined,use the guidance in Chapter 700 to determine theneed for a traffic barrier.

When a crossroad or road approach has steepforeslopes, there is the possibility that an errantvehicle might become airborne. Therefore, flattencrossroad and road approach foreslopes to 1:6where practical and at least to 1:4. Providesmooth transitions between the main lineforeslopes and the crossroad or road approachforeslopes. Where possible, move the crossroador road approach drainage away from the mainline. This can locate the pipe outside the designclear zone and reduce the length of pipe required.

430.09 Intersections(1) GeneralExcept as given below, design intersections tomeet the requirements in Chapter 910.

(2) Design VehicleFigure 430-2 is a guide for determining thedesign vehicle. Perform a field review to deter-mine intersection type, type of vehicle that usethe intersection, and adequacy of the existinggeometrics.

(3) AngleThe allowable angle between any two respectivelegs is between 60° and 120°. When realignmentis required to meet this angle requirement,consider realigning to an angle between 75°and 105°.

430.10 BridgesDesign all new and replacement bridges to fulldesing level (Chapter 440) unless a corridor orproject anlaysis justifies the use of modifieddesign level lane and shoulder widths. Evaluatebridges to remain in place using Figures 430-3and 4. Whenever possible, continue the roadwaylane widths across the bridge and adjust theshoulder widths.

DesignIntersection Type Vehicle

Junction of MajorTruck Routes WB-20

Junction of StateRoutes WB-12

Ramp Terminals WB-12

Other Rural SU1

Urban Industrial SU1

Urban Commercial P1

Residential P1

1When the intersection is on a transit or school busroute, use the BUS design vehicle. See Chapter1060 for additional guidance for transit facilitiesand for the BUS turning path templates.

Design VehiclesModified Design Level

Figure 430-2

Consider joint use with other modes of transpor-tation in lane and shoulder design. See Chapters1020, 1050, and 1060.

430.11 DocumentationThe following documents are to be preserved inthe project file. See Chapter 330.

� Design speed selection

� Existing roadway widths

� Stopping sight distance evaluation

� Justification for profile grade modification

� Existing crown and superelevation

� Intersection field review

Modified Design Level Design ManualPage 430-4 Metric Version May 2001

Modified Design Level for Multilane Highways and BridgesFigure 430-3

Multilane Divided Multilane Undivided

Trucks Under 10% Trucks 10% and Over Trucks Under 10% Trucks 10% and Over

Design Class MDL-1 MDL-2 MDL-3 MDL-4 MDL-5 MDL-6 MDL-7 MDL-8

Current ADT(1) Under4000

Over4000

Under4000

Over4000

Under4000

Over4000

Under4000

Over4000

Design Speed The posted speed, the proposed posted speed, or the operating speed, whichever is higher.

Traffic LanesNumberWidth

4 or more

3.3 m4 or more

3.3 m4 or more

3.3 m4 or more

3.6 m4 or more

3.3 m4 or more

3.3 m4 or more

3.3 m4 or more

3.6 m

Parking LanesUrban None None None None 2.4 m 2.4 m (2) 2.4 m 2.4 m (2)

Median WidthRuralUrban

ExistingExisting

ExistingExisting

ExistingExisting

ExistingExisting

0.6 m0.6 m

1.2 m0.6 m

1.2 m0.6 m

1.2 m0.6 m

Shoulder Width

Right (3)

Left (4)1.2 m0.6 m

1.8 m0.6 m

1.2 m0.6 m

1.8 m0.6 m

1.2 m 1.8 m (5) 1.2 m 1.8 m (5)

Minimum Width forBridges to Remain

in Place (6)(7)(8)7.3 m (9) 7.9 m (9) 7.3 m (9) 7.9 m (10) 14.6 m (9)

(9)(11)

15.2 m(9)(11)

15.2 m(10)(11)

16.5 m

Minimum Width forRehabilitation ofBridges to Remain

in Place (6)(12)(8)

8.4 m (9) 9.0 m (9) 8.4 m (9) 9.6 m (10) 16.2 m (9)(9)(11)(13)

18.0 m(9)(11)

16.8 m(10)(11)(13)

19.2 m

Minimum Width forReplacement Full Design Level Applies (14)

Access ControlSee Chapter 1420 and the Master Plan for Limited Access Highways, or WAC 468-52 andthe region’s Highway Access Management Classification Report

(1) If current ADT is approaching a borderline condition, consider designing for the higher classification.

(2) Parking restricted when ADT is over 15,000.

(3) When curb section is used, the minimum shoulder width from the edge of traveled way to the face of curb is1.2 m. On designated bicycle routes the minimum shoulder width is 1.2 m (See Chapter 1020).

(4) For lanes 3.3 m or more in width, the minimum shoulder width to the face of the curb is 0.3 m on the left.

(5) May be reduced by 0.6 m under urban conditions.

(6) Width is the clear distance between curbs or rails, whichever is less.

(7) Use these widths when a bridge within the project limits requires deck treatment or thrie beam retrofit only.

(8) For median widths 7.5 m or less, see Chapter 1120.

(9) Add 3.3 m for each additional lane.

(10) Add 3.6 m for each additional lane.

(11) Includes a 1.2 m median which may be reduced by 0.6 m under urban conditions.

(12) Use these widths when a bridge within the project limits requires any work beyond the treatment of the decksuch as bridge rail replacement, deck replacement, or widening.

(13) Includes 1.8 m shoulders — may be reduced by 0.6 m on each side under urban conditions.

(14) Modified design level lane and shoulder widths may be used when justified with a corridor or project analysis.

Design Manual Modified Design LevelMay 2001 Metric Version Page 430-5

Modified Design Level for Two-Lane Highways and BridgesFigure 430-4

Two-Lane Highways

Trucks Under 10% Trucks 10% and Over

Design Class MDL-9 MDL-10 MDL-11 MDL-12 MDL-13 MDL-14

Current ADT(1) Under 1000 1000-4000 Over 4000 Under 1000 1000-4000 Over 4000

Design Speed The posted speed, the proposed posted speed, or the operating speed, whicheveris higher.

Traffic Lane(2)

Width 3.3 m 3.3 m 3.3 m 3.3 m 3.6 m 3.6 m

Parking LanesUrban 2.4 m 2.4 m 2.4 m(3) 2.4 m 2.4 m 2.4 m(3)

Shoulder Width(4) 0.6 m 0.9 m(5) 1.2 m 0.6 m 0.9 m(5) 1.2 m

Minimum Width for Bridges

to Remain in Place (6)(7) 6.6 m(8) 7.2 m 8.5 m 6.6 m(8) 7.2 m 8.5 m

Minimum Width forRehabilitation of Bridges to

Remain in Place (7)(9)8.4 m(10) 9.6 m 9.6 m 8.4 m(10) 9.6 m 9.6 m

Minimum Width forReplacement Full Design Level Applies(11)

Access ControlSee Chapter 1420 and the Master Plan for Limited Access Highways, orWAC 468-52 and the region’s Highway Management Classification Report.

(1) If current ADT is approaching a borderline condition, consider designing for the higher classification.

(2) See Figures 430-5 and 430-6 for turning roadways.

(3) Parking restriction recommended when ADT exceeds 7,500.

(4) When curb section is used, the minimum shoulder width from the edge of traveled way to the face of curb is1.2 m. On designated bicycle routes the minimum shoulder width is 1.2 m (See Chapter 1020).

(5) For design speeds of 50 mph or less on roads of 2,000 ADT or less, width may be reduced by 0.3 m, withjustification.

(6) Use these widths when a bridge within the project limits requires deck treatment or thrie beam retrofit only.

(7) Width is the clear distance between curbs or rails, whichever is less.

(8) 6.0 m when ADT 250 or less.

(9) Use these widths when a bridge within the project limits requires any work beyond the treatment of the decksuch as bridge rail replacement, deck replacement, or widening.

(10) 7.8 m when ADT 250 or less.

(11) Modified design level lane and shoulder widths may be used when justified with a corridor or project analysis.

Modified Design Level Design ManualPage 430-6 Metric Version May 2001

Minimum Total Roadway Widths for Two-Lane Highway CurvesModified Design Level

Figure 430-5

Design Manual Modified Design LevelMay 2001 Metric Version Page 430-7

Minimum Total Roadway Widths for Two-Lane Highway Curves, D<90°Modified Design Level

Figure 430-6

Modified Design Level Design ManualPage 430-8 Metric Version May 2001

Evaluation for Stopping Sight Distancefor Crest Vertical CurvesModified Design Level

Figure 430-7

Design Manual Modified Design LevelMay 2001 Metric Version Page 430-9

Evaluation for Stopping Sight Distance for Horizontal CurvesModified Design Level

Figure 430-8

Modified Design Level Design ManualPage 430-10 Metric Version May 2001

Main Line Roadway SectionsModified Design Level

Figure 430-9

Design Manual Modified Design LevelMay 2001 Metric Version Page 430-11

Ramp Roadway SectionsModified Design Level

Figure 430-10

Design Manual Full Design LevelMay 2001 Metric Version Page 440-1

440 Full Design Level

Plans Preparation Manual, WSDOT, M 22-31

Local Agency Guidelines (LAG), M 36-63,WSDOT

A Policy on Geometric Design of Highways andStreets (Green Book), 1994, AASHTO

A Policy on Design Standards - Interstate System,1991, AASHTO

440.03 Definitionsauxiliary lane The portion of the roadwayadjoining the through lanes for parking, speedchange, turning, storage for turning, weaving,truck climbing, and other purposes supplemen-tary to through-traffic movement.

bikeway Any trail, path, part of a highway orshoulder, sidewalk, or any other traveled wayspecifically signed and/or marked for bicycletravel.

collector system Routes that primarily serve themore important intercounty, intracounty, andintraurban travel corridors, collect traffic fromthe system of local access roads and convey it tothe arterial system, and on which, regardless oftraffic volume, the predominant travel distancesare shorter than on arterial routes (RCW47.05.021).

design speed The speed used to determine thevarious geometric design features of the roadway.

frontage road An auxiliary road that is a localroad or street located on the side of a highwayfor service to abutting property and adjacentareas and for control of access.

functional classification The grouping ofstreets and highways according to the characterof the service they are intended to provide.

high pavement type Portland cement concretepavement or asphalt cement concrete pavementon treated base.

intermediate pavement type Asphalt cementconcrete pavement on an untreated base.

440.01 General440.02 References440.03 Definitions440.04 Functional Classification440.05 Terrain Classification440.06 Geometric Design Data440.07 Design Speed440.08 Traffic Lanes440.09 Shoulders440.10 Medians440.11 Curbs440.12 Parking440.13 Pavement Type440.14 Structure Width440.15 Grades

440.01 GeneralFull design level is the highest level of designand is used on new and reconstructed highways.These projects are designed to provide optimummobility, safety, and efficiency of traffic move-ment. The overall objective is to move thegreatest number of vehicles, at the highestallowable speed, and at optimum safety. Majordesign controls are functional classification,terrain classification, urban or rural surroundings,traffic volume, traffic character and composition,design speed, and access control.

440.02 ReferencesRevised Code of Washington (RCW) 47.05.021,Functional classification of highways.

RCW 47.24, City Streets as Part of State Highways

Washington Administrative Code (WAC)468-18-040, “Design standards for rearrangedcounty roads, frontage roads, access roads,intersections, ramps and crossings”

Standard Plans for Road, Bridge, and MunicipalConstruction (Standard Plans), M 21-01,WSDOT

Standard Specifications for Road, Bridge,and Municipal Construction (StandardSpecifications), M 41-10, WSDOT.

Full Design Level Design ManualPage 440-2 Metric Version May 2001

Interstate System A network of routes selectedby the state and the FHWA under terms of thefederal aid acts as being the most important to thedevelopment of a national system. The InterstateSystem is part of the principal arterial system.

lane A strip of roadway used for a single lineof vehicles.

lane width The lateral design width for a singlelane, striped as shown in the Standard Plans andStandard Specifications. The width of an existinglane is measured from the edge of traveled way tothe center of the lane line or between the centersof adjacent lane lines.

low pavement type Bituminous surfacetreatment.

median The portion of a divided highwayseparating the traveled ways for traffic inopposite directions.

minor arterial system A rural network ofarterial routes linking cities and other activitycenters that generate long distance travel and,with appropriate extensions into and throughurban areas, form an integrated network provid-ing interstate and interregional service (RCW47.05.021).

National Highway System (NHS) An intercon-nected system of principal arterial routes thatserves interstate and interregional travel; meetsnational defense requirements; and serves majorpopulation centers, international border crossings,ports, airports, public transportation facilities,other intermodal transportation facilities, andother major travel destinations. The InterstateSystem is a part of the NHS.

operating speed The speed at which driversare observed operating their vehicles duringfree-flow conditions. The 85th percentile ofthe distribution of observed speeds is mostfrequently used.

outer separation The area between the outsideedge of traveled way for through traffic and thenearest edge of traveled way of a frontage road.

posted speed The maximum legal speed asposted on a section of highway using regulatorysigns.

principal arterial system A connected networkof rural arterial routes with appropriate exten-sions into and through urban areas, including allroutes designated as part of the Interstate System,that serve corridor movements having travelcharacteristics indicative of substantial statewideand interstate travel (RCW 47.05.021).

roadway The portion of a highway, includingshoulders, for vehicular use. A divided highwayhas two or more roadways.

shoulder The portion of the roadwaycontiguous with the traveled way, primarily foraccommodation of stopped vehicles, emergencyuse, lateral support of the traveled way, and useby pedestrians and bicycles.

shoulder width The lateral width of theshoulder, measured from the outside edge of theoutside lane to the edge of the roadway.

traveled way The portion of the roadwayintended for the movement of vehicles, exclusiveof shoulders and lanes for parking, turning, andstorage for turning.

usable shoulder The width of the shoulder thatcan be used by a vehicle for stopping.

440.04 Functional ClassificationAs provided in RCW 47.05.021, the state high-way system is divided and classified according tothe character and volume of traffic carried by theroutes and distinguished by specific geometricdesign standards. The functional classificationsused on highways, from highest to lowest classi-fication, are Interstate, principal arterial, minorarterial, and collector. The higher functionalclasses give more priority to through trafficand less to local access.

The criteria used in making the functionalclassification consider the following:

• Urban population centers within and withoutthe state stratified and ranked accordingto size.

• Important traffic generating economicactivities, including but not limited torecreation, agriculture, government,business, and industry.

Design Manual Full Design LevelMay 2001 Metric Version Page 440-3

• Feasibility of the route, includingavailability of alternate routes within andwithout the state.

• Directness of travel and distance betweenpoints of economic importance.

• Length of trips.

• Character and volume of traffic.

• Preferential consideration for multiple servicewhich shall include public transportation.

• Reasonable spacing depending uponpopulation density.

• System continuity.

440.05 Terrain ClassificationTo provide a general basis of reference betweenterrain and geometric design, three classificationsof terrain have been established.

Level. Level to moderately rolling. This terrainoffers few or no obstacles to the construction ofa highway having continuously unrestrictedhorizontal and vertical alignment.

Rolling. Hills and foothills. Slopes rise and fallgently but occasional steep slopes might offersome restriction to horizontal and verticalalignment.

Mountainous. Rugged foothills, high steepdrainage divides, and mountain ranges.

Terrain classification pertains to the generalcharacter of the specific route corridor. Roadsin valleys or passes of mountainous areas mighthave all the characteristics of roads traversinglevel or rolling terrain and are usually classifiedas level or rolling rather than mountainous.

440.06 Geometric Design Data(1) State Highway SystemFor all projects designed to full design level, usethe geometric design data in Figures 440-4through 7b.

(2) State Highways as City StreetsWhen a state highway within an urban area iscoincident with and is a portion of a local agencyroadway, develop the design features in coopera-

tion with the local agency. For facilities on theNHS, use the design criteria in this manual asthe minimum for the functional class of the route.For facilities not on the NHS, the Local AgencyGuidelines may be used as minimum designcriteria; however, the use of WSDOT standardsis encouraged where feasible.

(3) City Streets and County RoadsPlan and design facilities that cities or countieswill be requested to accept as city streets orcounty roads according to the applicable designcriteria shown in:

• WAC 468-18-040.

• Local Agency Guidelines.

• The standards of the local agency that will berequested to accept the facility.

440.07 Design Speed

Vertical and horizontal alignment, sight distance,and superelevation will vary appreciably withdesign speed. Such features as traveled waywidth, shoulder width, and lateral clearances areusually not affected. See Chapters 620, 630, 640,and 650 for the relationships between designspeed, geometric plan elements, geometric profileelements, superelevation, and sight distance.

The choice of a design speed is influencedprincipally by functional classification, postedspeed, operating speed, terrain classification,traffic volumes, accident history, access control,and economic factors. However, a geometricdesign that adequately allows for future improve-ment is the major criterion, rather than strictlyeconomics. Categorizing a highway by a terrainclassification often results in arbitrary reductionsof the design speed when, in fact, the terrainwould allow a higher design speed withoutmaterially affecting the cost of construction.Savings in vehicle operation and other costsalone might be sufficient to offset the increasedcost of right of way and construction.

It is important to consider the geometricconditions of adjacent sections. Maintain auniform design speed for a significant segmentof highway.

Full Design Level Design ManualPage 440-4 Metric Version May 2001

Design speeds for each functional class are givenin Figures 4, 5a, 6a, and 7a. It is desirable that thedesign speed and the posted speed correlate asshown in Figure 440-1 and that the design speedbe not less than the operating speed.

Posted DesirableSpeed Design Speed

35 mph Not less thanor less the posted speed.

40 mph 5 mph overto 50 mph the posted speed

55 mph 10 mph overor higher the posted speed

Desirable Design SpeedFigure 440-1

Select a design speed for urban arterial streetsand highways with some access control and fairlylong distances between intersections as discussedabove. However, highway arterials that haveobvious “street-like” characteristics, operation-ally and physically, do not require a design speeddetermination. In such instances, closely spacedintersections and other operational constraintsusually limit vehicular speeds, negating thedesign speed factor.

440.08 Traffic LanesLane width and condition has a great influenceon safety and comfort. The added cost for widerlanes is offset, to some extent, by the reduction inshoulder maintenance cost due to the lessening ofwheel load concentrations at the edge of the lane.

Lanes 3.6 m wide provide desirable clearancebetween large vehicles where traffic volumesare high and a high number of large vehicles areexpected.

Highway capacity is also affected by the widthof the lanes. With narrow lanes, drivers mustoperate their vehicles closer (laterally) to eachother than they normally desire. To compensatefor this, drivers reduce their speed and increasethe headway, resulting in reduced capacity.

Figures 440-4 through 440-7b give the minimumlane width for the various design classes. SeeChapter 640 for guidance on width requirementson turning roadways.

440.09 ShouldersThe shoulder width is controlled by the functionalclassification of the roadway, the traffic volume,and the function the shoulder is to serve.

The more important shoulder functions are to:

(1) Provide space for:

• Stopping out of the traffic lanes.

• Escaping potential accidents or to reducetheir severity.

• Lateral clearance to roadside objects, such asguardrail (see Chapters 700 and 710).

• Pedestrian and bicycle use.

• Large vehicle off tracking on curves (seeChapter 640 and 910).

• Maintenance operations.

• Law enforcement.

• Bus stops (see Chapter 1060).

• Slow vehicles turnouts and shoulder driving(see Chapter 1010).

• Ferry holding lanes.

• A sense of openness contributing to driverease and freedom from strain.

• For use as a lane during reconstruction of thethrough lanes.

(2) Provide structural support for the traveledway.

(3) Improve sight distance in cut sections(see Chapter 650).

(4) Improve capacity.

(5) Reduce seepage adjacent to the traveledway by discharging storm water farther away.

For minimum overall shoulder widths based onfunctional classification and traffic volume, seeFigures 440-4 through 7b.

Design Manual Full Design LevelMay 2001 Metric Version Page 440-5

Guidance and width requirements for theshoulder functions with chapter references isin the referenced chapters. Figure 440-2 givesminimum overall and usable shoulder widths forother functions. For the remaining functionslisted, the benefits vary with the width of theshoulder.

The width of shoulder required for maintenanceoperations depends on the operation performedand the equipment needed. To be able to park amaintenance truck out of the through lane, 3.0 musable width is needed. For equipment withoutriggers, such as used to service luminaires andrepair guardrail, a width of 3.6 m is required or alane will need to be closed while the equipment isworking. Contact the region maintenance officeto determine the shoulder width for maintenanceoperations. When shoulder widths wider thancalled for in Figures 440-4 through 7b arerequested, compare the added cost of the widershoulders to the added benefits to maintenanceoperations and other benefits that may be derived.When the maintenance office requests a shoulderwidth different than for the design class, justifythe width selected.

Shoulder MinimumFunction Shoulder Width

Minimum lateral 0.6 mclearance and

structural support

Pedestrian or 1.2 m(1)

bicycle use

Stopping out of 1.8 m(2)

the traffic lanes

Law enforcement 1.8 m(2)

and Ferry holding

(1) Minimum usable shoulder width forbicycles. For additional information,see Chapter 1020 for bicycle andChapter 1025 for pedestrians.

(2) Minimum usable shoulder width, 3.0 mpreferred. See Chapters 1040 and1050 for additional information onenforcement areas.

Minimum Shoulder WidthFigure 440-2

The usable shoulder width is less than the con-structed shoulder width when vertical features(such as traffic barrier or walls) are at the edge ofthe shoulder. This is because drivers tend to shyaway from the perceived hazard of the verticalfeature. See Chapter 710 for the requiredwidening.

Provide a minimum clearance to roadside objectsso that the shoulders do not require narrowing.At existing bridge piers and abutments, shouldersless than full width to a minimum of 0.6 m may beused with design exception documentation. SeeChapter 700 for design clear zone and safetytreatment requirements.

Shoulder widths greater than 3.0 m may encourageuse as a travel lane. Therefore, use shoulderswider than this only where required to meet oneof the listed functions.

When curb section is used, the minimumshoulder width from the edge of traveled wayto the face of curb is given in Figure 440- 3.

440.10 MediansThe primary functions of a median are to:

• Separate opposing traffic.

• Provide for recovery of out-of-controlvehicles.

• Reduce head-on accidents.

• Provide an area for emergency parking.

• Allow space for left turn lanes.

• Minimize headlight glare.

• Allow for future widening.

For maximum efficiency, make medians highlyvisible both night and day. Medians may bedepressed, raised, or flush with the through lanes.

The width of a median is measured from edgeof traveled way to edge of traveled way andincludes the shoulders. The minimum medianwidth for each design class is given in Figures440-4 through 440-7b. When selecting a medianwidth, consider future needs such as wider leftshoulders when widening from four to six lanes.

Full Design Level Design ManualPage 440-6 Metric Version May 2001

LaneWidth

At locations where the median will be usedto allow vehicles to make a u-turn, considerincreasing the width to meet the needs of thevehicles making the u-turn. See Chapter 910for information on u-turn locations.

See Chapter 700 for barrier requirements andChapter 910 for left-turn lane design.

440.11 CurbsCurbing is used for the following purposes:

• Drainage control.

• Delineation of the roadway edge.

• Delineation of pedestrian walkways.

• Delineation of islands.

• Right of way reduction.

• Assist in access control.

• Prevention of mid-block left turns.

The two general classes of curbs are barrier curbsand mountable curbs (see the Standard Plans fordesigns). Precast traffic curb, precast block curb,and all extruded curbs are considered mountablecurbs.

Barrier curbs are 150 mm or more high with a facebatter not flatter than 1H:3V. They are used:

• To inhibit or at least discourage vehiclesfrom leaving the roadway.

• For walkway and pedestrian refugeseparations.

• For raised islands on which a traffic signal,or traffic signal hardware, is located.

When an overlay will reduce the height of abarrier curb to less than 150 mm, evaluate grindingto maintain curb height, or replacing the curb,verses the need to maintain a barrier curb. Donot reduce the height of a curb needed for oneof the three uses above to less than 100 mm.

Mountable curbs have a height of 150 mm or less,preferably 100 mm or less, with a sloping face thatis more readily traversed. When the face slopeis steeper than 1H:1V, the height of a mountablecurb is limited to 100 mm or less. They are usedwhere a curb is needed but barrier curb isnot justified.

Avoid using curbs if the same objective can beattained with pavement markings.

Where curbing is to be provided, ensure thatsurface water will drain.

Curbs can hamper snow removal operations.Contact the regional Operations Engineer whenconsidering curbing in areas of heavy snowfall.

In general, neither mountable nor barrier curbsare used on facilities with a posted speed greaterthan 40 mph. The exceptions are for predomi-nantly urban or rapidly developing areas wheresidewalks are provided or where traffic move-ments are to be restricted.

When curbing is used, provide the minimumshoulder widths shown in Figure 440-3. (Fortraffic islands, also see Chapter 910.)

Design Speed

≥50 mph <50 mph All

On Left On Right

3.6 m or 1.2 m min(1) 0.3 m(2) (3)wider

3.3 m 1.2 m min(1) 0.6 m(2) (3)

3.0 m 1.2 m min(1) 0.9 m(2) (3)

(1) Use the wider width when required for thefunctional class (Figures 440-5a through7b).

(2) When mountable curb is used on routeswith a posted speed of 35 mph or less,shoulder width is desirable but, withjustification, curb may be placed at theedge of traveled way.

(3) Use the width required for the functionalclass (Figures 440-5a through 7b).

(4) Measured from the edge of traveled wayto the face of the curb.

Shoulder Width for Curb(4)

Figure 440-3

440.12 ParkingIn urban areas and rural communities, land usemight require parking along the highway. Ingeneral, on-street parking decreases capacity,increases accidents, and impedes traffic flow.Therefore, it is desirable to prohibit parking.

Design Manual Full Design LevelMay 2001 Metric Version Page 440-7

Although design data for parking lanes areincluded on Figures 440-5a through 7b, considerthem only in cooperation with the municipalityinvolved. The lane widths given are the minimumfor parking.

440.13 Pavement TypeThe pavement types given in Figures 440-4through 7a are the recommended for each designclass. Submit Form 223-528, Pavement TypeDetermination to the OSC Materials Laboratoryfor a final determination of the pavement type touse. When a roadway is to be widened and theexisting pavement will remain, the new pavementtype may be the same as the existing without apavement type determination.

440.14 Structure WidthProvide a clear width between curbs on a bridgeequal to the approach roadway width (lanes plusshoulders). The structure widths given in Figures440-4 through 7a are the minimum bridge widthfor each design class.

Shy distance is not normally added to theroadway width for the bridge width. When abridge is in a run of roadside barrier, consideradding the shy distance on shorter bridges toprevent narrowing the roadway.

440.15 GradesGrades can have a pronounced effect on theoperating characteristics of the vehicles negotiat-ing them. Generally, passenger cars can readilynegotiate grades as steep as 5% without appre-ciable loss of speed from that maintained on levelhighways. Trucks, however, travel at the averagespeed of passenger cars on the level but displayup to a 5% increase in speed on downgrades anda 7% or more decrease in speed on upgrades(depending on length and steepness of the gradeas well as weight to horsepower ratio).

The maximum grades for the various functionalclasses and terrain conditions are shown inFigures 440-4 through 7a. For the effects of thesegrades on the design of a roadway see Chapters630 and 1010.

P65:DP/DMM

Full Design Level Design ManualPage 440-8 Metric Version May 2001

Design Manual Full Design LevelMay 2001 Metric Version Page 440-9

Geometric Design Data, InterstateFigure 440-4

Divided Multilane

Design Class I-1

Design Year (1)

Access Control(2)

Full

Separate Cross Traffic

HighwaysRailroads

AllAll

Design Speed (mph)Rural 80

(3)

Urban 70

Traffic Lanes

NumberWidth (m)

4 or more divided3.6

Median Width (m) 4 lane 6 lanes or more

Rural —Minimum(4)

Urban —Minimum124.8

156.6

Shoulder Width (m)Right of Traffic 3.0 3.0

Left of Traffic 1.2 3.0(5)

Pavement Type(6)

High

Right of Way(7)

Rural — Minimum Width (m) 19 from edge of traveled way

Urban — Minimum Width (m) As required (8)

Structures Width(9)

(m) Full roadway width each direction(10)

Grades (%)(11)

Design Speed (mph)

Type of Terrain 50 60 70 80

Level 4 3 3 3

Rolling 5 4 4 4

Mountainous 6 6 5 5

Interstate Notes:

1 The design year is 20 years after the year the construction is scheduled to begin.2 See Chapter 1420 for access control requirements.3 80 mph is the desirable design speed, with justification the design speed may be reduced to 60 mph in mountainous

terrain and 70 mph in rolling terrain.4 Independent alignment and grade is desirable in all rural areas and where terrain and development permits in urban

areas.5 For existing 6-lane roadways, existing 1.8 m left shoulders may remain when no other widening is required.6 Submit Form 223-528, Pavement Type Determination.7 Provide right of way width 3.0 m desirable, 1.5 m minimum, wider than the slope stake for fill and slope treatment for

cut. See Chapter 640 and the Standard Plans for slope treatment information.8 In urban areas, make right of way widths not less than those required for necessary cross section elements.9 See Chapter 1120 for minimum vertical clearance.10 For median widths 7.8 m or less, address bridge(s) in accordance with Chapter 1120.11 Grades 1% steeper may be used in urban areas where development precludes the use of flatter grades and for one-way

down grades except in mountainous terrain.

Full Design Level Design ManualPage 440-10 Metric Version May 2001

Geo

met

ric

Des

ign

Dat

a, P

rin

cip

al A

rter

ial

Fig

ure

440

-5a

Div

ided

Mu

ltilan

eT

wo

-Lan

eU

ndiv

ided

Mul

tilan

e

P-1

P-2

P-3

P-4

P-5

P-6

(1)

Desig

n C

lass

Rura

lU

rban

Rura

lU

rban

Rura

lU

rban

Rura

lU

rban

Rura

lU

rban

Rura

lU

rban

DH

V in

Desig

n Y

ear(2

)N

HS

Ove

r 201

(3)

61-2

00

(4)

60 a

nd u

nder

Non N

HS

Ove

r 1,5

00

Ove

r 700

Ove

r 301

101-3

00

100 a

nd U

nder

Ove

r 700

Access C

on

tro

lF

ull(5

)P

art

ial(5

)(5

)(5

)(5

)(5

)

Sep

arate

Cro

ss T

raff

ic

Hig

hw

ays

All

Where

Justif

ied

Where

Justif

ied

Where

Justif

ied

Where

Justif

ied

Where

Justif

ied

Railr

oads

All

All

All(6

)W

here

Justif

ied

(7)

Where

Justif

ied

(7)

Where

Justif

ied

(7)

Desig

n S

peed

(m

ph)(8

)70

7070

6070

6060

6070

60

Mounta

inous T

err

ain

(9)

5050

5040

5040

4030

4030

Traff

ic L

an

es

Num

ber

Wid

th (

m)

4 o

r m

ore

div

ided

3.6

4 o

r 6 d

ivid

ed

3.6

2 3.6

2 3.6

2 3.6

4 3.6

4 o

r 6

3.3

(10

)

Sh

ou

lde

r W

idth

(m

)R

ight of T

raffic

3.0

3.0

2.4

1.8

1.2

2.4

2.4

(11

)

Left o

f T

raffic

Variable

(12

)V

ariable

(12)

Me

dia

n W

idth

(m

)4 la

ne

12

(13

)4.8

184.8

1.2

0.6

(14

)

6 o

r m

ore

lanes

14.4

(13)

6.6

186.6

1.2

0.6

(14)

Parkin

g L

an

es W

idth

(m

) —

Min

imum

None

None

None

None

3.0

None

3.0

None

3.0

(15

)

Pavem

en

t T

yp

e(1

6)

Hig

hH

igh o

r in

term

edia

te

Rig

ht

of

Way

(17

) — M

in W

idth

(m

)(1

8)

(19)

(18)

(19)

3624

3624

3024

6524

Str

uctu

res W

idth

(m

)(20

)F

ull

roadw

ay w

idth

(21

)12.0

10.8

9.6

Full

roadw

ay w

idth

Oth

e r D

e sig

n C

ons i

dera

tions

-Urb

a n(2

2)

(22)

(22)

(22)

Gra

de

s (

%)(2

3)

Rura

l — D

esig

n S

peed (

mph)

Urb

an —

Desig

n S

peed (

mph)

Type o

f T

err

ain

4050

6070

8030

4050

60

Leve

l5

43

33

87

65

Rolli

ng

65

44

49

87

6

Mounta

inous

87

65

511

109

8

Design Manual Full Design LevelMay 2001 Metric Version Page 440-11

Geo

met

ric

Des

ign

Dat

a, P

rin

cip

al A

rter

ial

Fig

ure

440

-5b

Pri

ncip

al A

rter

ial

Not

es:

1Ju

stif

y th

e se

lect

ion

of a

P-6

sta

ndar

d.2

The

des

ign

year

is

20 y

ears

aft

er t

he y

ear

the

cons

truc

tion

is

sche

dule

d to

beg

in.

3W

here

DH

V e

xcee

ds 7

00,

cons

ider

fou

r la

nes.

Whe

n th

e vo

lum

e/ca

paci

ty r

atio

is

equa

l to

or

exce

eds

0.75

, co

nsid

er t

he n

eeds

for

a f

utur

e fo

ur-l

ane

faci

lity

. W

hen

cons

ider

ing

truc

k cl

imbi

ng l

anes

on

a P

-3 d

esig

n cl

ass

high

way

, pe

rfor

m a

n in

vest

igat

ion

to d

eter

min

e if

a P

-2 d

esig

n cl

ass

high

way

is

just

ifie

d.4

Whe

n co

nsid

erin

g a

mul

tila

ne h

ighw

ay,

perf

orm

an

inve

stig

atio

n to

det

erm

ine

if a

tru

ck c

lim

bing

lan

e or

pas

sing

lan

e w

ill

sati

sfy

the

need

. S

ee C

hapt

er 1

010.

5

See

Cha

pter

142

0 an

d th

e M

aste

r P

lan

for

Lim

ited

Acc

ess

Hig

hway

s fo

r ac

cess

con

trol

req

uire

men

ts.

Con

tact

the

OS

C D

esig

n O

ffic

e A

cces

s &

Hea

ring

s U

nit

for

addi

tion

alin

form

atio

n.

6A

ll m

ain

line

and

maj

or-s

pur

rail

road

tra

cks

wil

l be

sep

arat

ed.

Con

side

r al

low

ing

at-g

rade

cro

ssin

gs a

t m

inor

-spu

r ra

ilro

ad t

rack

s.7

Cri

teri

a fo

r ra

ilro

ad g

rade

sep

arat

ions

are

not

cle

arly

def

inab

le.

Eva

luat

e ea

ch s

ite

rega

rdin

g th

e ha

zard

pot

enti

al.

Pro

vide

jus

tifi

cati

on f

or r

ailr

oad

grad

e se

para

tion

s.8

The

se a

re t

he d

esig

n sp

eeds

for

lev

el a

nd r

olli

ng t

erra

in a

nd t

he p

refe

rred

for

mou

ntai

nous

ter

rain

. H

ighe

r de

sign

spe

eds

may

be

sele

cted

, w

ith

just

ific

atio

n.9

The

se d

esig

n sp

eeds

may

be

sele

cted

in

mou

ntai

nous

ter

rain

, w

ith

just

ific

atio

n.10

3.6

m la

nes

are

requ

ired

whe

n th

e tr

uck

DH

V is

6%

or

grea

ter.

11W

hen

curb

sec

tion

is

used

, th

e m

inim

um s

houl

der

wid

th f

rom

the

edg

e of

tra

vele

d w

ay t

o th

e fa

ce o

f cu

rb i

s 1.

2 m

. 12

Min

imum

lef

t sh

ould

er w

idth

is

to b

e as

fol

low

s: f

our

lane

s —

1.2

m:

six

or m

ore

lane

s —

3.0

m.

For

6-l

ane

road

way

s, e

xist

ing

1.8

m l

eft

shou

lder

s m

ay r

emai

n w

hen

noot

her

wid

enin

g is

req

uire

d.13

On

free

way

s or

exp

ress

way

s re

quir

ing

less

tha

n ei

ght

lane

s w

ithi

n th

e 20

-yea

r de

sign

per

iod,

pro

vide

suf

fici

ent

med

ian

or l

ater

al c

lear

ance

and

rig

ht o

f w

ay t

o pe

rmit

addi

tion

of

a la

ne i

n ea

ch d

irec

tion

if

requ

ired

by

traf

fic

incr

ease

aft

er t

he 2

0-ye

ar p

erio

d.14

Whe

n si

gnin

g is

req

uire

d in

the

med

ian

of a

six

-lan

e se

ctio

n, t

he m

inim

um w

idth

is

1.8

m. I

f ba

rrie

r is

to

be i

nsta

lled

at

a fu

ture

dat

e, a

2.4

m m

inim

um m

edia

n is

req

uire

d.15

Res

tric

t pa

rkin

g w

hen

AD

T i

s ov

er 1

5,00

0.16

Sub

mit

For

m 2

23-5

28,

Pav

emen

t T

ype

Det

erm

inat

ion.

17P

rovi

de r

ight

of

way

wid

th 3

.0 m

des

irab

le,

1.5

m m

inim

um,

wid

er t

han

the

slop

e st

ake

for

fill

and

slo

pe t

reat

men

t fo

r cu

t. S

ee C

hapt

er 6

40 a

nd t

he S

tand

ard

Pla

ns f

or s

lope

tre a

tmen

t in

form

a tio

n.18

19 m

fro

m e

dge

of t

rave

led

way

.19

Mak

e ri

ght

of w

ay w

idth

s no

t le

ss t

han

thos

e re

quir

ed f

or n

eces

sary

cro

ss s

ecti

on e

lem

ents

.20

See

Cha

pter

112

0 fo

r th

e m

inim

um v

erti

cal

clea

ranc

e.21

For

med

ian

wid

ths

7.8

m o

r le

ss,

addr

ess

brid

ges

in a

ccor

danc

e w

ith

Cha

pter

112

0.22

For

bic

ycle

req

uire

men

ts s

ee C

hapt

er 1

020.

For

ped

estr

ian

and

side

wal

k r

equi

rem

ents

see

Cha

pter

102

5. C

urb

requ

irem

ents

are

in

44

0.1

1 . L

ater

al c

lear

ance

s fr

om t

he f

ace

ofcu

rb t

o ob

stru

ctio

n ar

e in

Cha

pter

700

.23

Exc

ept

in m

ount

aino

us t

erra

in, g

rade

s 1%

ste

eper

may

be

used

in

urba

n ar

eas

whe

re d

evel

opm

ent

prec

lude

s th

e us

e of

fla

tter

gra

des

or f

or o

ne-w

ay d

owng

rade

s.

Full Design Level Design ManualPage 440-12 Metric Version May 2001

Geo

met

ric

Des

ign

Dat

a, M

ino

r A

rter

ial

Fig

ure

440

-6a

Div

ided

Mu

ltilan

eT

wo

-Lan

eU

ndiv

ided

Mul

tilan

e

M-1

M-2

M-3

M-4

M-5

(1)

Desig

n C

lass

Rura

lU

rban

Rura

lU

rban

Rura

lU

rban

Rura

lU

rban

Rura

lU

rban

DH

V in

Desig

n Y

ear(2

)N

HS

Ove

r 201

(3)

61-2

00

(4)

60 a

nd U

nder

Non N

HS

Ove

r 700

Ove

r 401

201-4

00

200 a

nd U

nder

Ove

r 700

Access C

on

tro

l(5

)(5

)(5

)(5

)(5

)

Sep

arate

Cro

ss T

raff

ic

Hig

hw

ays

Where

Warr

ante

dW

here

Warr

ante

dW

here

Warr

ante

dW

here

Warr

ante

dW

here

Warr

ante

d

Railr

oads

All

All(6

)W

here

Warr

ante

d(7

)W

here

Warr

ante

d(7

)W

here

Warr

ante

d (7

)

Desig

n S

peed

(m

ph)(8

)70

7060

7060

6060

7060

Mounta

inous T

err

ain

(9)

5050

4050

4040

3040

30

Traff

ic L

an

es

Num

ber

4 o

r 6 d

ivid

ed

22

24

4 o

r 6

Wid

th (

m)

3.6

3.6

3.6

3.6

3.6

3.3

(10

)

Sh

ou

lde

r W

idth

(m

)R

ight of T

raffic

3.0

2.4

1.8

1.2

2.4

2.4

(11

)

Left o

f T

raffic

Variable

(12

)

Me

dia

n W

idth

(m

)4 la

ne

184.8

1.2

0.6

(13

)

6 la

ne

186.6

Parkin

g L

an

es W

idth

(m

) —

Min

imum

None

None

None

3.0

None

3.0

None

3.0

(14

)

Pavem

en

t T

yp

e(1

5)

Hig

hA

s r

equired

Hig

h o

r In

term

edia

te

Rig

ht

of

Way

(16

) — M

in W

idth

(m

)(1

7)

(18)

3624

3624

3024

4524

Str

uctu

res (

m)(1

9)

Full

Ro a

d wa y

Wid

th(2

0)

1210.8

9.6

Full

Roadw

ay W

idth

Oth

e r D

e sig

n C

ons i

dera

tions

-Urb

a n(2

1)

(21)

(21)

(21)

Gra

de

s (

%)(2

2)

Rura

l — D

esig

n S

peed (

mph)

Urb

an —

Desig

n S

peed (

mph)

Type o

f T

err

ain

4050

6070

8030

4050

60

Leve

l5

43

33

87

65

Rolli

ng

65

44

49

87

6

Mounta

inous

87

65

511

109

8

Design Manual Full Design LevelMay 2001 Metric Version Page 440-13

Geo

met

ric

Des

ign

Dat

a, M

ino

r A

rter

ial

Fig

ure

440

-6b

Min

or A

rter

ial

Not

es:

1Ju

stif

y th

e se

lect

ion

of a

n M

-5 s

tand

ard.

2T

he d

esig

n ye

ar i

s 20

yea

rs a

fter

the

yea

r th

e co

nstr

ucti

on i

s sc

hedu

led

to b

egin

.3

Whe

re D

HV

exc

eeds

700

, co

nsid

er f

our

lane

s. W

hen

the

volu

me/

capa

city

rat

io i

s eq

ual

to o

r ex

ceed

s 0.

75,

cons

ider

the

nee

ds f

or a

fut

ure

four

-lan

e fa

cili

ty.

Whe

nco

nsid

erin

g tr

uck

clim

bing

lan

es a

n M

-2 d

esig

n cl

ass

high

way

, pe

rfor

m a

n in

vest

igat

ion

to d

eter

min

e if

an

M-1

des

ign

clas

s hi

ghw

ay i

s ju

stif

ied.

4W

hen

cons

ider

ing

a m

ulti

lane

hig

hway

, pe

rfor

m a

n in

vest

igat

ion

to d

eter

min

e if

a t

ruck

cli

mbi

ng l

ane

or p

assi

ng l

ane

wil

l sa

tisf

y th

e ne

ed.

See

Cha

pter

101

0.

5S

ee C

hapt

er 1

420

and

the

Mas

ter

Pla

n fo

r L

imit

ed A

cces

s H

ighw

ays

for

acce

ss c

ontr

ol r

equi

rem

ents

. C

onta

ct t

he

OS

C D

esig

n O

ffic

e A

cces

s &

Hea

ring

s U

nit

for

addi

tion

alin

form

atio

n.

6A

ll m

ain

line

and

maj

or-s

pur

rail

road

tra

cks

wil

l be

sep

arat

ed.

Con

side

r al

low

ing

at-g

rade

cro

ssin

gs a

t m

inor

-spu

r ra

ilro

ad t

rack

s.7

Cri

teri

a fo

r ra

ilro

ad g

rade

sep

arat

ions

are

not

cle

arly

def

inab

le.

Eva

luat

e ea

ch s

ite

rega

rdin

g th

e ha

zard

pot

enti

al.

Pro

vide

jus

tifi

cati

on f

or r

ailr

oad

grad

e se

para

tion

s.8

The

se a

re t

he d

esig

n sp

eeds

for

lev

el a

nd r

olli

ng t

erra

in a

nd t

he p

refe

rred

for

mou

ntai

nous

ter

rain

. H

ighe

r de

sign

spe

eds

may

be

sele

cted

, w

ith

just

ific

atio

n.9

The

se d

esig

n sp

eeds

may

be

sele

cted

in

mou

ntai

nous

ter

rain

, w

ith

just

ific

atio

n.10

Whe

n th

e tr

uck

DH

V i

s 6%

or

grea

ter,

con

side

r 3.

6 m

lan

es.

11W

hen

curb

sec

tion

is

used

, th

e m

inim

um s

houl

der

wid

th f

rom

the

edg

e of

tra

vele

d w

ay t

o th

e fa

ce o

f cu

rb i

s 1.

2 m

. 12

The

min

imum

lef

t sh

ould

er w

idth

is

1.2

m f

or f

our

lane

s an

d 3.

0 m

for

six

or

mor

e la

nes.

For

6-l

ane

road

way

s, e

xist

ing

1.8

m l

eft

shou

lder

s m

ay r

emai

n w

hen

no o

ther

wid

enin

g is

req

uire

d.13

Whe

n si

gnin

g is

req

uire

d in

the

med

ian

of a

six

-lan

e se

ctio

n, t

he m

inim

um w

idth

is

1.8

m. I

f ba

rrie

r is

to

be i

nsta

lled

at

a fu

ture

dat

e, a

2.4

m m

inim

um m

edia

n is

req

uire

d.14

Res

tric

t pa

rkin

g w

hen

AD

T i

s ov

er 1

5,00

0.15

Sub

mit

For

m 2

23-5

28,

Pav

emen

t T

ype

Det

erm

inat

ion.

16P

rovi

de r

ight

of

way

wid

th 3

.0 m

des

irab

le,

1.5

m m

inim

um,

wid

er t

han

the

slop

e st

ake

for

fill

and

slo

pe t

reat

men

t fo

r cu

t. S

ee C

hapt

er 6

40 a

nd t

he S

tand

ard

Pla

ns f

or s

lope

tre a

tmen

t in

form

a tio

n.17

19

m f

rom

edg

e of

trav

eled

way

18M

ake

righ

t of

way

wid

ths

not

less

tha

n th

ose

requ

ired

for

nec

essa

ry c

ross

sec

tion

ele

men

ts.

19S

ee C

hapt

er 1

120

for

the

min

imum

ver

tica

l cl

eara

nce.

20F

or m

edia

n w

idth

s 7.

8 m

or

less

, ad

dres

s br

idge

s in

acc

orda

nce

wit

h C

hapt

er 1

120.

21F

or b

icyc

le r

equi

rem

ents

see

Cha

pter

102

0.

For

ped

estr

ian

and

side

wal

k r

equi

rem

ents

see

Cha

pter

102

5. C

urb

requ

irem

ents

are

in

44

0.1

1 . L

ater

al c

lear

ance

s fr

om th

e fa

ce o

fcu

rb t

o ob

stru

ctio

n ar

e in

Cha

pter

700

.22

Exc

ept

in m

ount

aino

us t

erra

in, g

rade

s 1%

ste

eper

may

be

used

in

urba

n ar

eas

whe

re d

evel

opm

ent

prec

lude

s th

e us

e of

fla

tter

gra

des

or f

or o

ne-w

ay d

owng

rade

s.

Full Design Level Design ManualPage 440-14 Metric Version May 2001

Geo

met

ric

Des

ign

Dat

a, C

olle

cto

rF

igu

re 4

40-7

a

Und

ivid

ed M

ultil

ane

Tw

o-L

an

e

C-1

C-2

C-3

C-4

Desig

n C

lass

Rura

lU

rban

Rura

lU

rban

Rura

lU

rban

Rura

lU

rban

DH

V in

Desig

n Y

ear(1

)N

HS

Ove

r 301

(2)

201-3

00

(3)

200 a

nd u

nder

Non N

HS

Ove

r 900

Ove

r 501

301-5

00

300 a

nd U

nder

Access C

on

tro

l(4

)(4

)(4

)(4

)

Sep

arate

Cro

ss T

raff

ic

Hig

hw

ays

Where

Warr

ante

dW

here

Warr

ante

dW

here

Warr

ante

dW

here

Warr

ante

d

Railr

oads

Where

Warr

ante

d(5

)A

ll(5)

Where

Warr

ante

d(5

)W

here

Warr

ante

d(5

)

Desig

n S

peed

(m

ph)(6

)70

6070

6070

6060

60

Mounta

inous T

err

ain

(7)

4030

5040

5040

4030

Traff

ic L

an

es

Num

ber

44 o

r 6

22

2

Wid

th (

m)

3.6

3.3

(8)

3.6

3.6

3.6

Sh

ou

lde

r W

idth

(m

)2.4

2.4

(9)

2.4

1.8

1.2

Me

dia

n W

idth

— M

inim

um

(m

)1.2

0.6

(10

)

Parkin

g L

an

es W

idth

(m

) —

Min

imum

None

3.0

None

None

3.0

None

3.0

Pavem

en

t T

yp

e(1

1)

Hig

h o

r In

term

edia

teA

s r

equired

Rig

ht

of

Way

(12

) (m

)45

2436

2436

2430

24

Str

uc

ture

s W

idth

(m

)(13

)F

ull

Roadw

ay W

idth

12.0

10.8

9.6

Oth

e r D

e sig

n C

ons i

dera

tions

-Urb

a n(1

4)

(14)

(14)

(14)

Gra

de

s (

%)(1

5)

Rura

l — D

esig

n S

peed (

mph)

Urb

an —

Desig

n S

peed (

mph)

Type o

f T

err

ain

3040

5060

7030

4050

60

Leve

l7

76

54

99

76

Rolli

ng

98

76

511

108

7

Mounta

inous

1010

98

612

1210

9

Design Manual Full Design LevelMay 2001 Metric Version Page 440-15

Geo

met

ric

Des

ign

Dat

a, C

olle

cto

rF

igu

re 4

40-7

b

Col

lect

or N

otes

:

1T

he d

esig

n ye

ar i

s 20

yea

rs a

fter

the

yea

r th

e co

nstr

ucti

on i

s sc

hedu

led

to b

egin

.2

Whe

re D

HV

exc

eeds

900

, co

nsid

er f

our

lane

s. W

hen

the

volu

me/

capa

city

rat

io i

s eq

ual

to o

r ex

ceed

s 0.

85,

cons

ider

the

nee

ds f

or a

fut

ure

four

-lan

e fa

cili

ty.

Whe

nco

nsid

erin

g tr

uck

clim

bing

lan

es o

n a

C-2

des

ign

clas

s hi

ghw

ay,

perf

orm

an

inve

stig

atio

n to

det

erm

ine

if a

C-1

des

ign

clas

s hi

ghw

ay i

s ju

stif

ied.

3W

hen

cons

ider

ing

a m

ulti

lane

hig

hway

, pe

rfor

m a

n in

vest

igat

ion

to d

eter

min

e if

a t

ruck

cli

mbi

ng l

ane

or p

assi

ng l

ane

wil

l sa

tisf

y th

e ne

ed.

See

Cha

pter

101

0.

4S

ee C

hapt

er 1

420

and

the

Mas

ter

Pla

n fo

r L

imit

ed A

cces

s H

ighw

ays

for

acce

ss c

ontr

ol r

equi

rem

ents

. C

onta

ct t

he

OS

C D

esig

n O

ffic

e A

cces

s &

Hea

ring

s U

nit

for

addi

tion

alin

form

atio

n.

5C

rite

ria

for

rail

road

gra

de s

epar

atio

ns a

re n

ot c

lear

ly d

efin

able

. E

valu

ate

each

sit

e re

gard

ing

the

haza

rd p

oten

tial

. P

rovi

de j

usti

fica

tion

for

rai

lroa

d gr

ade

sepa

rati

ons.

6 T

hese

are

the

des

ign

spee

ds f

or l

evel

and

rol

ling

ter

rain

and

the

pre

ferr

ed f

or m

ount

aino

us t

erra

in.

Hig

her

desi

gn s

peed

s m

ay b

e se

lect

ed,

wit

h ju

stif

icat

ion.

7 T

hese

des

ign

spee

ds m

ay b

e se

lect

ed i

n m

ount

aino

us t

erra

in,

wit

h ju

stif

icat

ion.

8C

onsi

der

3.6

m la

nes

whe

n th

e tr

uck

DH

V i

s 6%

or

grea

ter.

9W

hen

curb

sec

tion

is

used

, th

e m

inim

um s

houl

der

wid

th f

rom

the

edg

e of

tra

vele

d w

ay t

o th

e fa

ce o

f cu

rb i

s 1.

2 m

. 10

Whe

n si

gnin

g is

req

uire

d in

the

med

ian

of a

six

-lan

e se

ctio

n, t

he m

inim

um w

idth

is

1.8

m m

edia

n. I

f ba

rrie

r is

to

be i

nsta

lled

at

a fu

ture

dat

e, a

2.4

m m

inim

um m

edia

n is

requ

ired

.11

Sub

mit

For

m 2

23-5

28,

Pav

emen

t T

ype

Det

erm

inat

ion.

12P

rovi

de r

ight

of

way

wid

th 3

.0 m

des

irab

le,

1.5

m m

inim

um,

wid

er t

han

the

slop

e st

ake

for

fill

and

slo

pe t

reat

men

t fo

r cu

t. S

ee C

hapt

er 6

40 a

nd t

he S

tand

ard

Pla

ns f

or s

lope

tre a

tmen

t in

form

a tio

n.13

See

Cha

pter

112

0 fo

r th

e m

inim

um v

erti

cal

clea

ranc

e.14

For

bic

ycle

req

uire

men

ts,

see

Cha

pter

102

0.

For

ped

estr

ian

and

side

wal

k r

equi

rem

ents

see

Cha

pter

102

5. C

urb

requ

irem

ents

are

in

44

0.1

1 . L

ater

al c

lear

ance

s fr

om t

he f

ace

of c

urb

to o

bstr

ucti

on a

re i

n w

ith

Cha

pter

700

.15

Exc

ept

in m

ount

aino

us t

erra

in, g

rade

s 1%

ste

eper

may

be

used

in

urba

n ar

eas

whe

re d

evel

opm

ent

prec

lude

s th

e us

e of

fla

tter

gra

des

or f

or o

ne-w

ay d

owng

rade

s.

620 Geometric Plan Elements

620.01 General620.02 References620.03 Definitions620.04 Horizontal Alignment620.05 Distribution Facilities620.06 Number of Lanes and Arrangement620.07 Pavement Transitions620.08 Procedures620.09 Documentation

620.01 GeneralThis chapter provides guidance on the design ofhorizontal alignment, frontage roads, number oflanes, the arrangement of the lanes, and pavementtransitions. See the following chapters foradditional information:

Chapter Subject

430 All roadway width requirementsfor modified design level

440 Lane and shoulder widthrequirements for full design level

440 Shoulder width requirements at curbs

640 Open highway and ramp lanewidths on turning roadways forfull design level

640 Superelevation rate and transitions

650 Sight distance

910 Requirements for islands

620.02 ReferencesWashington Administrative Code (WAC)468-18-040, “Design standards for rearrangedcounty roads, frontage roads, access roads,intersections, ramps and crossings”

Utilities Manual, M 22-87, WSDOT

Plans Preparation Manual, M 22-31, WSDOT

Manual on Uniform Traffic Control Devices forStreets and Highways (MUTCD), USDOT,FHWA; including the Washington State Modifi-cations to the MUTCD, M 24-01, WSDOT

Right of Way Manual, M 26-01, WSDOT

Local Agency Guidelines (LAG), M 36-63,WSDOT

A Policy on Geometric Design of Highways andStreet, 1994, AASHTO

620.03 Definitionsauxiliary lane The portion of the roadwayadjoining the traveled way for parking, speedchange, turning, storage for turning, weaving,truck climbing, passing, and other purposessupplementary to through-traffic movement

basic number of lanes The minimum number ofgeneral purpose lanes designated and maintainedover a significant length of highway

frontage road An auxiliary road that is a localroad or street located on the side of a highway forservice to abutting property and adjacent areasand for control of access

outer separation The area between the outsideedge of the through highway lanes and the insideedge of a frontage road

turning roadway A curve on an open highway,a curve on a ramp, or a connecting roadwaybetween two intersecting legs of an intersection

620.04 Horizontal Alignment(1) GeneralHorizontal and vertical alignments (Chapter 630)are the primary controlling elements for highwaydesign. It is important to coordinate these twoelements with design speed, drainage, intersec-tion design, and aesthetic principles in the earlystages of design.

Figures 620-1a and 1c show both desirable andundesirable alignment examples for use withthe following considerations:

(a) Make the highway alignment as directas possible and still blend with the topographywhile considering developed and undevelopedproperties, community boundaries, andenvironmental concerns.

Design Manual Geometric Plan ElementsMay 2001 Metric Version Page 620-1

(b) Make highway alignment consistent by:

• Using gentle curves at the end of longtangents.

• Using a transition area of moderate curvaturebetween the large radius curves of ruralareas and the small radius curves ofpopulated areas.

• Making horizontal curves visible toapproaching traffic.

(c) Avoid minimum radii and short curvesunless:

• Restrictive conditions are present and arenot readily or economically avoidable.

• On two-lane highways, minimum radii willresult in tangent sections long enough forneeded passing.

(d) Avoid any abrupt change in alignment.Design reverse curves with an interveningtangent long enough for complete superelevationtransition for both curves. See Chapter 640 formore information on superelevation transitions.

(e) Avoid the use of curves in the samedirection connected by short tangents (brokenback curves); substitute a single larger curve.

(f) Avoid compound curves on open highwayalignment if a simple curve can be obtained.When compound curves are used, make theshorter radius at least two-thirds the longerradius. Make the total arc length of a compoundcurve not less than 150 m.

(g) On divided multilane highways, takeadvantage of independent alignment to producea flowing alignment along natural terrain.

(h) The preferred locations for bridges,interchanges, intersections, and temporaryconnections are on tangent sections in clearview of the driver.

(i) On two-lane, two-way highways, strivefor as much passing sight distance as possible.(See Chapter 650.)

(2) Horizontal Curve RadiiDesign speed is the governing element ofhorizontal curves. For guidance regarding designspeed selection see Chapter 440 for full designlevel, Chapter 430 for modified design level, andChapter 940 for ramps.

Use the following factors to determine the radiusfor a curve:

• Stopping sight distance where sightobstructions are on the inside of a curve. Thefollowing are examples of sight obstructions:median barrier, bridges, walls, cut slopes,wooded areas, buildings, and guardrail. SeeChapter 650 to check for adequate stoppingsight distance for the selected design speed.

• Superelevation is the rotation or banking ofthe roadway cross section to overcome partof the centrifugal force that acts on a vehicletraversing a curve. Design information on therelationship between design speed, radius ofcurve, and superelevation is in Chapter 640.

• Coordinate vertical and horizontal alignment(see Chapter 630).

• For aesthetic reasons, on open highways, thedesirable minimum curve length is 450 m andthe maximum is around 1500 m. See Figures620-1a through 1c.

Spiral curves, although no longer used on newhighway construction or major realignment, stillexist on Washington highways. Spirals were usedto transition between tangents and circular curveswith the curvature rate increasing from tangentto curve and decreasing from curve to tangent.Spirals do not pose an operational concern andmay remain in place.

620.05 Distribution Facilities(1) GeneralIn addition to the highway under consideration,other facilities can be provided to distributetraffic to and from the highway and to fulfillaccess requirements. Highway flexibility canbe augmented by:

• Frontage roads

• Collector distributor roads

Geometric Plan Elements Design ManualPage 620-2 Metric Version April 1998

630 Geometric Profile Elements

Plans Preparation Manual, M 22-31, WSDOT

Manual on Uniform Traffic Control Devices forStreets and Highways (MUTCD), USDOT,FHWA; including the Washington State Modifi-cations to the MUTCD, M 24-01, WSDOT

Local Agency Guidelines (LAG), M 36-63,WSDOT

A Policy on Geometric Design of Highways andStreet, 1994, AASHTO

630.03 Vertical Alignment(1) Design ControlsThe following are general controls for developingvertical alignment (also see Figures 630-1aand 1c):

• Use a smooth grade line with gradualchanges, consistent with the class of highwayand character of terrain. Avoid numerousbreaks and short grades.

• Avoid “ roller coaster” or “hidden dip”profiles by use of gradual grades madepossible by heavier cuts and fills or byintroducing some horizontal curvature inconjunction with the vertical curvature.

• Avoid grades that will affect truck speedsand, therefore, traffic operations.

• Avoid broken back grade lines with shorttangents between two vertical curves.

• Use long vertical curves to flatten gradesnear the top of long steep grades.

• Where at-grade intersections occur onroadways with moderate to steep grades,it is desirable to flatten or reduce the gradethrough the intersection.

• Establish the subgrade at least 0.3 m abovethe high water table (real or potential) oras recommended by the region MaterialsEngineer. Consider the low side ofsuperelevated roadways.

630.01 General630.02 References630.03 Vertical Alignment639.04 Coordination of Vertical and

Horizontal Alignments630.05 Airport Clearance630.06 Railroad Crossings630.07 Procedures630.08 Documentation

630.01 GeneralVertical alignment (roadway profile) consists ofa series of gradients connected by vertical curves.It is mainly controlled by:

• Topography

• Class of highway

• Horizontal alignment

• Safety

• Sight distance

• Construction costs

• Drainage

• Adjacent land use

• Vehicular characteristics

• Aesthetics

This chapter provides guidance for the design ofvertical alignment. See the following chapters foradditional information:

Chapter Subject

440 Maximum grade for eachfunctional class

620 Horizontal alignment

650 Sight distance

630.02 ReferencesWashington Administrative Code (WAC)468-18-040, “Design standards for rearrangedcounty roads, frontage roads, access roads,intersections, ramps and crossings”

Design Manual Geometric Profile ElementsApril 1998 Metric Version Page 630-1

• When a vertical curve takes place partly orwholly in a horizontal curve, coordinate thetwo as discussed in 630.04.

(2) Minimum Length of VerticalCurves

The minimum length of a vertical curve iscontrolled by design speed, the requirements forstopping sight distance, and the change in grade.See Chapter 650 to design vertical curves to meetstopping sight distance requirements.

In addition to stopping sight distance require-ments, the minimum length of a vertical curve, inmeters, is equal to the design speed, in miles perhour. For aesthetics, the desirable length of avertical curve is two to three times the lengthrequired for stopping sight distance.

(3) Maximum GradesAnalyze grades for their effect on trafficoperation because they may result in undesirabletruck speeds. Maximum grades are controlled byfunctional class of the highway, terrain type, anddesign speed (Chapter 440).

(4) Minimum GradesMinimum grades are used to meet drainagerequirements. Avoid selecting a “ roller coaster”or “hidden dip” profile merely to accommodatedrainage.

Minimum ditch gradients of 0.3% on pavedmaterials and 0.5% on earth can be obtainedindependently of roadway grade. Medians, longsag vertical curves, and relatively flat terrainare examples of areas where independent ditchdesign may be justified. A closed drainagesystem may be needed as part of an independentditch design.

(5) Length of GradeThe desirable maximum length of grade isthe maximum length on an upgrade at whicha loaded truck will operate without a 15 mphreduction. Figure 630-2 gives the desirablemaximum length for a given percent of grade.For grades that are not at a constant percent, usethe average. For grades longer than the desirablemaximum, consider an auxiliary climbing lane(Chapter 1010).

When long steep downgrades are unavoidable,consider an emergency escape ramp (Chapter1010).

(6) Alignment on StructuresAvoid high skew, vertical curvature, horizontalcurvature, and superelevation on structures, butdo not sacrifice safe roadway alignment toachieve this.

630.04 Coordination of Verticaland Horizontal AlignmentsDo not design horizontal and vertical alignmentindependently. Coordinate them to obtain safety,uniform speed, pleasing appearance, and efficienttraffic operation. Coordination can be achievedby plotting the location of the horizontal curveson the working profile to help visualize thehighway in three dimensions. Perspective plotswill also give a view of the proposed alignment.Figures 630-1a and 1b show sketches of desirableand undesirable coordination of horizontal andvertical alignment.

Guides for the coordination of the vertical andhorizontal alignment are as follows:

• Balance curvature and grades. Using steepgrades to achieve long tangents and flatcurves, or excessive curvature to achieveflat grades, are both poor design.

• Vertical curvature superimposed onhorizontal curvature generally results in amore pleasing facility. Successive changesin profile not in combination with horizontalcurvature may result in a series of dips notvisible to the driver.

• Do not begin or end a horizontal curve at ornear the top of a crest vertical curve. Thiscondition can be unsafe, especially at night,if the driver does not recognize the beginningor ending of the horizontal curve. Safety isimproved if the horizontal curve leads thevertical curve, that is, the horizontal curveis made longer than the vertical curve inboth directions.

Geometric Profile Elements Design ManualPage 630-2 Metric Version May 2001

Design Manual Geometric Cross SectionMay 2001 Metric Version Page 640-1

640 Geometric Cross Section

640.02 ReferencesWashington Administrative Code (WAC468-18-040), “Design standards for rearrangedcounty roads, frontage roads, access roads,intersections, ramps and crossings”

Standard Plans for Road, Bridge, and MunicipalConstruction (Standard Plans), M 21-01,WSDOT

Plans Preparation Manual, WSDOT, M 22-31

Highway Runoff Manual, M 31-16, WSDOT

Local Agency Guidelines (LAG), M 36-63,WSDOT

Standard Specifications for Road, Bridge,and Municipal Construction (StandardSpecifications), M 41-10,WSDOT.

WSDOT Pavement Guide for Design, Evaluationand Rehabilitation (Pavement Guide), WA-RD335.1, WSDOT

A Policy on Geometric Design of Highways andStreets (Green Book), 1994, AASHTO

640.03 Definitionsauxiliary lane The portion of the roadwayadjoining the through lanes for parking, speedchange, turning, storage for turning, weaving,truck climbing, and other purposes supplemen-tary to through-traffic movement.

high pavement type Portland cement concretepavement or asphalt cement concrete on atreated base.

intermediate pavement type Asphalt cementconcrete pavement on an untreated base.

lane A strip of roadway used for a single lineof vehicles.

lane width The lateral design width for a singlelane, striped as shown in the Standard Plans andthe Standard Specifications. The width of anexisting lane is measured from the edge oftraveled way to the center of the lane line orbetween the centers of successive lane lines.

640.01 General640.02 References640.03 Definitions640.04 Roadways640.05 Superelevation640.06 Medians and Outer Separations640.07 Roadsides640.08 Roadway Sections640.09 Documentation

640.01 GeneralGeometric cross sections for state highways aregoverned by functional classification criteria,traffic volume, and whether the highway is in arural or urban area. See Chapter 440 for guidanceon selecting a design class.

High Occupancy Vehicle (HOV) lanes must beconsidered when continuous through lanes are tobe added within the limits of an urban area over200,000 population (Chapter 1050).

When a state highway within an incorporated cityor town is a portion of a city street, the designfeatures must be developed in cooperation withthe local agency. For city streets and county roadsthat are not part of the state highway system, useChapter 468-18 WAC and the Local AgencyGuidelines.

See the following chapters for additionalinformation:

Chapter Subject

430 all roadway widths for modifieddesign level

440 lane and shoulder widths for fulldesign level

440 shoulder widths at curbs

910 requirements for islands

940 lane and shoulder widths for ramps

Geometric Cross Section Design ManualPage 640-2 Metric Version May 2001

low pavement type Bituminous surfacetreatment.

median The portion of a divided highwayseparating the traveled ways for traffic inopposite directions.

outer separation The area between the outsideedge of traveled way for through traffic and thenearest edge of traveled way of a frontage road.

roadway The portion of a highway, includingshoulders, for vehicular use. A divided highwayhas two or more roadways.

shoulder The portion of the roadway contiguouswith the traveled way, primarily for accommoda-tion of stopped vehicles, emergency use, lateralsupport of the traveled way, and use bypedestrians.

shoulder width The lateral width of the shoulder,measured from the outside edge of the outsidelane to the edge of the roadway.

superelevation The rotation of the roadway crosssection in such a manner as to overcome part ofthe centrifugal force that acts on a vehicletraversing a curve.

superelevation runoff The length of highwayneeded to accomplish the change in cross slopefrom a level section to a fully superelevatedsection, or vice versa.

superelevation transition length The length ofhighway needed to change the cross slope fromnormal crown or normal pavement slope to fullsuperelevation.

tangent runout The length of highway neededto change the cross slope from normal crown toa section with adverse crown removed (level).

traveled way The portion of the roadwayintended for the movement of vehicles, exclusiveof shoulders and lanes for parking, turning, andstorage for turning.

turning roadway A curve on an open highway,a ramp, or the connecting portion of roadwaybetween two intersecting legs of an intersection.

640.04 RoadwaysThe cross sections shown in Figures 640-3, 4, 5,6a, and 6b represent minimum standards for fulldesign level.

For the specific type of roadway section seeChapter 440 and for pavement type details seethe Pavement Guide.

(1) Traveled Way Cross SlopeThe cross slope on tangents and curves is a mainelement in cross section design. The cross slopeor crown on tangent sections and large radiuscurves is complicated by two contradictingcontrols. Reasonably steep cross slopes aredesirable to aid in water runoff and to minimizeponding as a result of pavement imperfectionsand unequal settlement. However, steep crossslopes are undesirable on tangents because of thetendency for vehicles to drift to the low side ofthe roadway. Cross slopes greater than 2% arenoticeable in steering and increase susceptibilityto sliding to the side on icy or wet pavements.

A 2% cross slope is normally used for tangentsand large radius curves on high and intermediatepavement types.

In some areas, a somewhat steeper cross slopemay be desirable to improve roadway runoff,although it is undesirable operationally. For theseareas, with justification, a 2.5% cross slope maybe used.

On low pavement types, such as bituminoussurface treatment, the cross slope may beincreased to 3% to allow for reducedconstruction control and greater settlement.

Superelevation on curves is determined by thedesign speed and the radius of the curve. See640.05 for guidance on superelevation design.

(2) Turning Roadway WidthsThe roadway on a curve may need to be widenedto make the operating conditions comparable tothose on tangents. There are two main reasons todo this. One is the offtracking of vehicles, suchas trucks and buses. The other is the increaseddifficulty drivers have in keeping their vehiclesin the center of the lane.

Design Manual Geometric Cross SectionMay 2001 Metric Version Page 640-3

(a) Two-lane two-way roadways. Figure640-7a shows the traveled way width W for two-lane two-way roadways. For values of R betweenthose given, interpolate W and round up to thenext tenth of a meter.

Minimum traveled way width W based on thedelta angle of the curve is shown in Figure640-7b. Round W to the nearest tenth of a meter.

(b) Two-lane one-way roadways. Figure640-8a shows the traveled way width for two-lane one-way turning roadways, including twolane ramps and four lane divided highways. Forvalues of R between those given, interpolate Wand round up to the next tenth of a meter. Treateach direction of travel of multilane dividedfacilities as a one-way roadway.

Minimum width W based on the delta angle ofthe curve is shown in Figure 640-8b. Round Wto the nearest tenth of a meter.

To keep widths to a minimum, traveled waywidths for Figures 640-8a and 8b were calculatedusing the WB-12 design vehicle. When volumesare high for both trucks larger than the WB-12and other traffic, consider using the widths fromFigures 640-7a and 7b.

(c) One-lane one-way roadways. Figure640-9a shows the traveled way width for one-laneone-way turning roadways, including one laneramps. For values of R between those given,interpolate W and round up to the next tenth ofa meter.

For minimum widths based on the delta angle ofthe curve, use Figure 640-9b for one-lane road-ways using the radius to the outer edge of thetraveled way and Figure 640-9c for one-laneroadways using the radius on the inner edgeof the traveled way. Round W to the nearesttenth of a meter.

Build shoulder pavements at full depth forone-lane one-way roadways because, to keepwidths to a minimum, traveled way widthswere calculated using the WB-12 design vehiclewhich may force larger vehicles to encroach onthe shoulders.

(d) Other roadways.

• For multilane two-way undivided roadwaysuse the following:

W =

Where:

W = The multilane roadway width.

Wa = The width from 640.04(2)(a)for a two-lane two-way roadway.

N = The total number of lanes.

• For one-way roadways with more than twolanes, for each lane in addition to two, addthe standard lane width for the highwayfunctional class from Chapter 440 to thewidth from 640.04(2)(b).

• For three-lane ramps with HOV lanes, seeChapter 1050.

(e) All roadways. Full design shoulder widthsfor the highway functional class or ramp areadded to the traveled way width to determinethe total roadway width.

If the total roadway width deficiency is less than0.6 m on existing roadways that are to remain inplace, correction is not required.

When widening

• Traveled way widening may be constructedon the inside of the traveled way or dividedequally between the inside and outside.

• Place final marked center line, and anycentral longitudinal joint, midway betweenthe edges of the widened traveled way.

• Provide widening throughout the curvelength.

• For widening on the inside, make transitionson a tangent, where possible.

• For widening on the outside, develop thewidening by extending the tangent. Thisavoids the appearance of a reverse curvethat a taper would create.

• For widening of 1.8 m or less, use a 1:25taper, for widths greater than 1.8 m use a1:15 taper.

Wa × N 2

Geometric Cross Section Design ManualPage 640-4 Metric Version May 2001

(3) ShouldersPave the shoulders of all highways where highor intermediate pavement types are used. Wherelow pavement type is used, treat the roadwayfull width.

Shoulder cross slopes are normally the same asthe cross slopes for adjacent lanes. With justifica-tion, shoulder slopes may be increased to 6%.The maximum difference in slopes between thelane and the shoulder is 8%. Examples of loca-tions where it may be desirable to have a shouldergrade different than the adjacent lane are:

• Where curbing is used.

• Where shoulder surface is bituminous, gravel,or crushed rock.

• Where overlays are planned and it isdesirable to maintain the grade at the edgeof the shoulder.

• On divided highways with depressed medianswhere it is desirable to drain the runoff intothe median.

• On the high side of the superelevation oncurves where it is desirable to drain stormwater or melt water away from the roadway.

When asphalt concrete curb is used, see theStandard Plans for required widening. Wideningis normally required when traffic barrier isinstalled (see Chapter 710).

It is preferred that curb not be used on high speedfacilities. In some areas, curb may be needed tocontrol runoff water until ground cover is attainedto prevent erosion. Plan for the removal of thecurb when the ground cover becomes adequate.Arrange for curb removal with regional mainte-nance as part of the future maintenance plans.When curb is used in conjunction with guardrail,see Chapter 710 for guidance.

Figures 640-10a and 10b represent shoulderdetails and requirements.

640.05 SuperelevationTo maintain the desired design speed, highwayand ramp curves are usually superelevated toovercome part of the centrifugal force that actson a vehicle.

(1) Superelevation Rates for OpenHighways and RampsThe maximum superelevation rate allowed foropen highways or ramps is 10%. (See Figure640-11a.)

Base superelevation rate and its correspondingradius for open highways on Figure 640-11a,Superelevation Rate (10% Max), with thefollowing exceptions:

• Figure 640-11b, Superelevation Rate(6% Max), may be used under the followingconditions:

1. Urban conditions without limited access

2. Mountainous areas or locations thatnormally experience regular accumulationsof snow and ice

3. Short-term detours (generally imple-mented and removed in one constructionseason). For long-term detours, consider ahigher rate up to 10%, especially whenassociated with a main line detour.

• Figure 640-11c, Superelevation Rate (8%Max), may be used for existing roadways andfor the urban, mountainous, and snow and iceconditions that are less severe or where the6% rate will not work; for example, wherea curve with a radius less than the minimumfor the design speed from Figure 640-11bis required.

Design the superelevation for ramps the sameas for open highways. With justification, rampsin urban areas with a design speed of 35 mph orless, Figure 640-12 may be use to determinethe superelevation.

Round the selected superelevation rate to thenearest full percent.

Document which set of curves is being used and,when a curve other than the 10% maximum rateis used, document why the curve was selected.

Depending on design speed, construct largeradius curves with a normal crown section andsuperelevate curves with smaller radii in accor-dance with the appropriate superelevation fromFigures 640-11a through 11c. The minimumradii for normal crown sections are shown inFigure 640-1.

Design Manual Geometric Cross SectionMay 2001 Metric Version Page 640-5

Minimum Radius forDesign Speed Normal Crown

(mph) Section (m)

25 750

30 1020

35 1335

40 1695

45 2095

50 2540

55 3030

60 3565

70 4480

80 5510

Minimum Radius forNormal Crown Section

Figure 640-1

(2) Existing CurvesEvaluate the superelevation on an existing curveto determine its adequacy. Use the followingequation:

R =

Where:

R = The minimum allowable radiusof the curve in meters.

V = Design speed in mph

e = Superelevation rate in percent

f = Side friction factor from Figure640-2

Superelevation is deficient when the radius isless that the minimum from the equation.

For preservation projects, where the existingpavement is to remain in place, thesuperelevation on existing curves may beevaluated with a ball banking analysis.

Address deficient superelevation as provided in640.05 (1).

Design Speed Side Friction(mph) Factor f

20 17

25 16

30 16

35 15

40 15

45 14

50 14

60 12

70 10

80 8

Side Friction FactorFigure 640-2

(3) Turning Movements atIntersectionsCurves associated with the turning movements atintersections are superelevated assuming greaterfriction factors than open highway curves. Sincespeeds of turning vehicles are not constant andcurve lengths are not excessive, higher frictionfactors can be tolerated. Use superelevation ratesas high as practical, consistent with curve lengthand climatic conditions. Figure 640-12 showsacceptable ranges of superelevation for givendesign speed and radius. It is desirable to use thevalues in the upper half or third of the specifiedrange whenever possible. Use judgment inconsidering local conditions such as snow andice. When using high superelevation rates onshort curves, provide smooth transitions withmerging ramps or roadways.

(4) Superelevation Runoff forHighway CurvesFor added comfort and safety, provide uniformsuperelevation runoff over a length adequate forthe likely operating speeds.

Provide transitions for all superelevated highwaycurves as specified in Figures 640-13a through13e. Which transition to use depends on thelocation of the pivot point, the direction of thecurve, and the roadway cross slope.

2.04V2

e + f

Geometric Cross Section Design ManualPage 640-6 Metric Version May 2001

Consider the profile of the edge of traveled way.To be pleasing in appearance, do not let it appeardistorted. The combination of superelevationtransition and grade may result in a hump or dipin the profile of the edge of traveled way. Whenthis happens, the transition may be lengthenedto eliminate the hump or dip. If the hump ordip cannot be eliminated this way, pay specialattention to drainage in the low areas.

When reverse curves are necessary, providesufficient tangent length for complete super-elevation runoff for both curves (that is, from fullsuperelevation of the first curve to level to fullsuperelevation of the second curve). If tangentlength is longer than this but not sufficient toprovide standard super transitions (that is, fromfull superelevation of the first curve to normalcrown to full superelevation of the second curve),increase the superelevation runoff lengths untilthey abut. This provides one continuous transi-tion, without a normal crown section, similar toDesigns C2 and D2 in Figures 640-13c and 3dexcept full super will be attained rather than thenormal pavement slope as shown.

Superelevation runoff is permissible on structuresbut not desirable. Whenever practical, strive forfull super or normal crown slopes on structures.

(5) Superelevation Runoff forRamp CurvesSuperelevation transition lengths for one-laneramps are shown in Figure 640-14a and 14b.For multilane ramps, use the method for highwaycurves (Figures 640-13a through 13e).

Superelevation transition lengths (LT) given inFigures 640-14a and 14b are for a single 4.5 mlane. They are based on maximum cross slopechange between the pivot point and the edgeof the traveled way over the length of thesuperelevation transition. Maximum relativeslopes for specific design speeds are similarto those given for highway curves.

For a single 4.5 m lane, use the distances given inthe LT column for LR wherever possible. The LBdistances will give the maximum allowable rateof cross slope change. Use the LB distances onlywith justification where the LT distance cannotbe achieved.

For ramps wider than 4.5 m, adjust the LBdistance by the equation for LR. If the resultis larger than the LT distance, round upwardto the next whole meter; if it is smaller, use theLT distance.

640.06 Medians and OuterSeparations(1) PurposeThe main function of a median is to separateopposing traffic lanes. The main function ofan outer separation is to separate the mainroadway from a frontage road. Medians andouter separations also provide space for:

• Drainage facilities

• Undercrossing bridge piers

• Vehicle storage space for crossing and leftturn movements at intersections

• Headlight glare screens, including plantedor natural foliage

• Visual buffer of opposing traffic

• Safety refuge areas for errant or disabledvehicles

• Storage space for snow and water fromtraffic lanes

• Increased safety, comfort, and ease ofoperations

(2) DesignIn addition to Figures 640-15a through 15c, referto other applicable sections for minimum designrequirements. Median widths in excess of theminimums are highly desirable. No attempt hasbeen made to cover all the various gradingtechniques that are possible on wide, variable-width medians. Considerable latitude in treatmentis intended, provided the requirements of mini-mum geometrics, safety, and aesthetics are metor exceeded.

When the horizontal and vertical alignmentsof the two roadways of a divided highway areindependent of each other, determine medianslopes in conformance with Figure 640-3.Unnecessary clearing, grubbing, and grading

Design Manual Geometric Cross SectionMay 2001 Metric Version Page 640-7

within wide medians is undesirable. Give prefer-ence to selective thinning and limited reshapingof the natural ground. For slopes into the face oftraffic barriers, see Chapter 710.

In areas where land is expensive, make aneconomic comparison of wide medians to narrowmedians with their barrier requirements. Considerright of way, construction, maintenance, andaccident costs. The widths of medians need notbe uniform. Make the transition between medianwidths as long as feasible.

Independent horizontal and vertical alignment,rather than parallel alignment, is desirable.

When using concrete barriers in depressedmedians or on curves, provide for surface drain-age on both sides of the barrier. The transversenotches in the base of precast concrete barrierare not intended to be used as a drainage featurebut rather as pick-up points when placingthe sections.

640.07 Roadsides(1) Side SlopesThe Cut Slope Selection tables on Figures 640-3,4, 5, and 6b are for preliminary estimates orwhere no other information is available. Designthe final slope as recommended in the soils orgeotechnical report.

When designing side slopes, fit the slope selectedfor any cut or fill into the existing terrain to givea smooth transitional blend from the constructionto the existing landscape. Slopes flatter thanrecommended are desirable, especially within theDesign Clear Zone. Slopes not steeper than 1:4,with smooth transitions where the slope changes,will provide a reasonable opportunity to recovercontrol of an errant vehicle. Where mowing iscontemplated, slopes must not be steeper than1:3. If there will be continuous traffic barrieron a fill slope, and mowing is not contemplated,the slope may be steeper than 1:3.

In cases of unusual geological features or soilconditions, treatment of the slopes will dependupon results of a review of the location by theregion’s Materials Engineer.

Do not disturb existing stable cut slopes just tomeet the slopes given in the Cut Slope Selectiontables on Figures 640-3, 4, 5, and 6b. When anexisting slope is to be revised, document thereason for the change.

If borrow is required, consider obtaining it byflattening cut slopes uniformly on one or bothsides of the highway. Where considering wastingexcess material on an existing embankmentslope, consult the region’s Materials Engineerto verify that the foundation soil will support theadditional material.

In all cases, provide for adequate drainage fromthe roadway surface and adequate drainage inditches. See 640.07(4) for details on drainageditches in embankment areas.

At locations where vegetated filter areas ordetention facilities will be established to improvehighway runoff water quality, provide appropri-ate slope, space, and soil conditions for thatpurpose. See the Highway Runoff Manual fordesign criteria and additional guidance.

Rounding, as shown in the Standard Plans, isrequired at the top of all roadway cut slopes,except for cuts in solid rock. Unless Class Bslope treatment is called for, Class A slopetreatment is used. Call for Class B slopetreatment where space is limited, such aswhere right of way is restricted.

(2) Roadway Sections in Rock CutsTypical sections for rock cuts, illustrated inFigures 640-16a and 16b, are guides for thedesign and construction of roadways throughrock cuts. Changes in slope or fallout area arerecommended when justified. Base the selectionof the appropriate sections on an engineeringstudy and the recommendations of the region’sMaterials Engineer and Landscape Architect.Olympia Service Center Materials Labconcurrence is required.

There are two basic design treatments applicableto rock excavation (Figures 640-16a and 16b).Design A applies to most rock cuts. Design Bis a talus slope treatment.

Geometric Cross Section Design ManualPage 640-8 Metric Version May 2001

(a) Design A. This design is shown in stagedevelopment to aid the designer in selecting anappropriate section for site conditions in regardto backslope, probable rockfall, hardness of rock,and so forth.

The following guidelines apply to the variousstages shown in Figure 640-16a.

• Stage 1 is used where the anticipated quantityof rockfall is small, adequate fallout widthcan be provided, and the rock slope is 1:1/2or steeper. Controlled blasting is recom-mended in conjunction with Stage 1construction.

• Stage 2 is used when a “rocks in the road”problem exists or is anticipated. Considerit on flat slopes where rocks are apt to rollrather than fall.

• Stage 3 represents full implementation of allprotection and safety measures applicable torock control. Use it only when extremerockfall conditions exist.

Show Stage 3 as ultimate stage for futureconstruction on the PS&E plans if there isany possibility that it will be needed.

The use of Stage 2 or 3 alternatives (concretebarrier) is based on the designer’s analysis ofthe particular site. Considerations include main-tenance, size and amount of rockfall, probablevelocities, availability of materials, ditch capac-ity, adjacent traffic volumes, distance fromtraveled lane, and impact severity. Incorporateremovable sections in the barrier at approxi-mately 60 m intervals. Appropriate terminaltreatment is required (Chapter 710).

Occasionally, the existing ground above the topof the cut is on a slope approximating the designcut slope. The height (H) is to include the exist-ing slope or that portion that can logically beconsidered part of the cut. The cut slope selectedfor a project must be that required to effectstability of the existing material.

Benches may be used to increase slope stability;however, the use of benches may alter the designrequirements for the sections given in Figure640-16a.

The necessity for benches, their width, andvertical spacing is established only after anevaluation of slope stability. Make benches atleast 6 m wide. Provide access for maintenanceequipment at the lowest bench, and to the higherbenches if feasible. Greater traffic benefits in theform of added safety, increased horizontal sightdistance on curves, and other desirable attributesmay be realized from widening a cut ratherthan benching.

(b) Design B. A talus slope treatment is shownin Design B (Figure 640-16b). The rock protec-tion fence is placed at any one of the threelocations shown but not in more than one positionat a particular location. The exact placement ofthe rock protection fence in talus slope areasrequires considerable judgment and should bedetermined only after consultation with theregion’s Materials Engineer.

• Fence position a is used when the cliffgenerates boulders less than 0.2 m3 in size,and the length of the slope is greater than100 m.

• Fence position b is the preferred location formost applications.

• Fence position c is used when the cliffgenerates boulders greater than 0.2 m3 insize, regardless of the length of the slope.On short slopes, this may require placingthe fence less than 30 m from the base ofthe cliff.

• Use of gabions may be considered instead ofthe rock protection shown in fence position a.However, gabion treatment is consideredsimilar to a wall and, therefore, requiresappropriate face and end protection forsafety (Chapter 710).

Use of the alternate shoulder barrier is basedon the designer’s analysis of the particular site.Considerations similar to those given forDesign A alternatives apply.

Rock protection treatments other than thosedescribed above may be required for cut slopesthat have relatively uniform spalling surfaces,consult with the region’s Materials Engineer.

Design Manual Geometric Cross SectionMay 2001 Metric Version Page 640-9

(3) Stepped SlopesStepped slopes are a construction methodintended to promote early establishment ofvegetative cover on the slopes. They consist of aseries of small horizontal steps or terraces on theface of the cut slope. Soil conditions dictate thefeasibility and necessity of stepped slopes. Theyare to be considered only on the recommendationof the region’s Materials Engineer (Chapter 510).Consult region’s landscape personnel for appro-priate design and vegetative materials to beused. See Figure 640-17 for stepped slopedesign details.

(4) Drainage Ditches in EmbankmentAreasWhere it is necessary to locate a drainage ditchadjacent to the toe of a roadway embankment,consider the stability of the embankment. Adrainage ditch placed immediately adjacent tothe toe of an embankment slope has the effectof increasing the height of the embankment bythe depth of the ditch. In cases where the founda-tion soil is weak, the extra height could resultin an embankment failure. As a general rule,the weaker the foundation and the higher theembankment, the farther the ditch should be fromthe embankment. Consult the region’s MaterialsEngineer for the proper ditch location.

When topographic restrictions exist, consider anenclosed drainage system with appropriate inletsand outlets. Do not steepen slopes to providelateral clearance from toe of slope to ditchlocation, thereby necessitating traffic barriersor other protective devices.

Maintenance operations are also facilitated byadequate width between the toe of the slope andan adjacent drainage ditch. Where this type offacility is anticipated, provide sufficient rightof way for access to the facility and place thedrainage ditch near the right of way line.

Provide for disposition of the drainage collectedby ditches in regard to siltation of adjacentproperty, embankment erosion, and other unde-sirable effects. This may also apply to cut slopetop-of-slope ditches.

(5) Bridge End SlopesBridge end slopes are determined by severalfactors, including: location, fill height, depthof cut, soil stability, and horizontal and verticalalignment. Close coordination between the OSCBridge and Structures Office and the region isnecessary to ensure proper slope treatment(Chapter 1120).

Early in the preliminary bridge plan development,determine preliminary bridge geometrics, endslope rates, and toe of slope treatments. Figure640-18a provides guidelines for use of slope ratesand toe of slope treatments for overcrossings.Figure 640-18b shows toe of slope treatmentsto be used on the various toe conditions.

640.08 Roadway SectionsProvide a typical section for inclusion in thePS&E for each general type used on the mainroadway, ramps, detours, and frontage or otherroads. See the Plans Preparation Manual forrequirements.

640.09 DocumentationThe following documents are to be preserved inthe project file. See Chapter 330.

� Justification for cross slopes other than2% on tangents.

� Justification for shoulder cross slopesnot the same as the cross slopes for theadjacent lane.

� Documentation of superelevation maxi-mum rate being used and justification fora rate other than 10%maximum.

� Justification for the use of LB on rampcurves when the minimum transitioncannot be achieved.

� Documentation of the reasons formodifying an existing cut slope.

� Engineering study and recommendationsfor rock cuts.

� Materials Engineer recommendation forstepped slopes.

� Materials Engineer recommendation forditch location at the toe of fill.

P65:DP/DMM

Geometric Cross Section Design ManualPage 640-10 Metric Version May 2001

Divided Highway Roadway SectionsFigure 640-3

(1) See Figures 640-10a and 10b for shoulderdetails. See Chapter 440 for minimumshoulder width.

(2) Generally, the crown slope will be as follows:

• Four-lane highway — slope all lanesaway from the median.

• Six-lane highway — slope all lanes awayfrom the median unless high rainfallintensities would indicate otherwise.

• Eight-lane highway — slope two of thefour directional lanes to the right and twoto the left unless low rainfall intensitiesindicate that all four lanes could besloped away from the median.

(3) See Chapter 440 for minimum number andwidth of lanes. See Figures 640-8a and 8band 640.04(2) for turning roadway width.

(4) See Figures 640-15a through 15c for mediandetails. See Chapter 440 for minimummedian width.

(5) Where practical, consider flatter slopes forthe greater fill heights and ditch depths.

(6) Widen and round foreslopes steeper than1:4 as shown on Figure 640-10b.

(7) Cut slopes steeper than 1:2 may be usedwhere favorable soil conditions exist orstepped construction is used. See Chapter700 for clear zone and barrier requirements.

(8) Fill slopes as steep as 1:11/2 may be usedwhere favorable soil conditions exist.See Chapter 700 for clear zone and barrierrequirements.

(9) This table is for preliminary estimates orwhere no other information is available.Design the final slope as recommendedin the soils or geotechnical report. Do notdisturb existing stable slopes just to meetthe slopes given in this table.

See filland ditchslopeselectiondata

.15 m min

0.6 mmin

2% 2%

(6)

See cut slopeselection data

See fill and ditch slopeselection data

(1) (3) (4) (3) (1)

(2) (2) 2%2% 2% 2% 2% 2%

Height of fill/depth Slope not steeperof ditch (m) than (5)

0 - 3 1 : 6

3 - 6 1 : 4

6 - 9 1 : 3 (6)

over 9 1 : 2 (6) (8)

Fill and Ditch Slope Selection

Height of Slope notcut (m) steeper than

0 - 1.5 1 : 6

1.5 - 6 1 : 3

over 6 1 : 2 (7)

Cut Slope Selection (9)

Class I, P-1, P-2, M-1

Design Manual Geometric Cross SectionMay 2001 Metric Version Page 640-11

(1) See Figures 640-10a and 10b for shoulderdetails. See Chapter 440 for minimumshoulder width.

(2) See Chapter 440 for minimum number andwidth of lanes. See Figures 640-7a and 7band 640.04(2) for turning roadway width.

(3) See Chapter 440 for minimum median width.

(4) Where practical, consider flatter slopes forthe greater fill heights and ditch depths.

(5) Cut slopes steeper than 1:2 may be usedwhere favorable soil conditions exist orstepped construction is used. See Chapter700 for clear zone and barrier requirements.

(6) Fill slopes up to 1:11/2 may be used wherefavorable soil conditions exist. See Chapter700 for clear zone and barrier requirements.

(7) Widen and round foreslopes steeper than1:4 as shown on Figure 640-10b.

(8) This table is for preliminary estimates orwhere no other information is available.Design the final slope as recommendedin the soils or geotechnical report. Do notdisturb existing stable slopes just to meetthe slopes given in this table.

Undivided Multilane Highway Roadway SectionsFigure 640-4

Height of fill/depth Slope notof ditch (m) steeper than (4)

0 - 1.5 1 : 6

1.5 - 6 1 : 4

6 - 9 1 : 3 (7)

over 9 1 : 2 (6) (7)

Fill and Ditch Slope Selection

Height of Slope notcut (m) steeper than

0 -1.5 1 : 4

over 1.5 1 : 2 (5)

Cut Slope Selection (8)

See fill andditch slopeselectiondata

(7)

2%2%

2% 2%

0.15 m min0.45 m min

See fill and ditchslope selection

See cut slopeselection data

(1) (2) (3) (2) (1)

Class P-6,M-5,C-1

Geometric Cross Section Design ManualPage 640-12 Metric Version May 2001

Two-Lane Highway Roadway SectionsFigure 640-5

(1) See Figures 640-10a and 10b for shoulderdetails. See Chapter 440 for minimumshoulder width.

(2) See Chapter 440 for minimum width oflanes. See Figures 640-7a and 7b and640.04(2) for turning roadway width.

(3) The minimum ditch depth is 0.60 m forDesign Class P-3 and 0.45 m for DesignClass P-4, P-5, M-2, M-3, M-4, C-2, C-3,and C-4.

(4) Where practical, consider flatter slopes forthe greater fill heights.

(5) Fill slopes up to 1:11/2 may be used wherefavorable soil conditions exist. See Chapter700 for clear zone and barrier requirements.

(6) Cut slopes steeper than 1:2 may be usedwhere favorable soil conditions exist orstepped construction is used. See Chapter700 for clear zone and barrier requirements.

(7) Widen and round foreslopes steeperthan 1:4, as shown on Figure 640-10b.

(8) This table is for preliminary estimates orwhere no other information is available.Design the final slope as recommendedin the soils or geotechnical report. Do notdisturb existing stable slopes just to meetthe slopes given in this table.

Design class P-3, P-4, P-5, M-3,of highway M-2, C-2 (4) M-4, C-3, C-4

Height of fill/depthof ditch (m) Slope not steeper than

0 - 3 1 : 6 1 : 4

3 - 6 1 : 4 1 : 4

6 - 9 1 : 3 (7) 1 : 3 (7)

over 9 1 : 2 (5) (7) 1 : 2 (5) (7)

Fill and Ditch Slope Selection

See fill andditch slopeselection

(7)

2%

2%

2%0.15 m min(3)

See fill and ditch slopeselection dataSee cut

slope selection

(1) (1)

2% 2%

(2) (2)

Design Class P-3,P-4,P-5,M-2,M-3,M-4,C-2,C-3,C-4

Design class P-3, P-4, P-5, M-3, M-4,of highway M-2, C-2 C-3, C-4

Height of cut (m) Slope not steeper than

0 - 1.5 1 : 6 1 : 4

1.5 - 6 1 : 3 1 : 2 (6)

over 6 1 : 2 (6) 1 : 2 (6)

Cut Slope Selection (8)

Design Manual Geometric Cross SectionMay 2001 Metric Version Page 640-13

For notes, dimensions, and slope selection tables see Figure 640-6b

Ramp Roadway SectionsFigure 640-6a

Geometric Cross Section Design ManualPage 640-14 Metric Version May 2001

Ramp Roadway SectionsFigure 640-6b

(1) See Figures 640-10a and 10b for shoulderdetails. See Chapter 940 for minimumshoulder widths.

(2) See Chapter 940 for minimum ramp lanewidths.

• For one-lane ramp turning roadwayssee Figures 640-9a thru 9c for traveledway width.

• For two-lane one-way ramp turningroadways, see Figures 640-8a & 8b fortraveled way width.

• For two-way ramps treat each directionas a separate one-way roadway.

(3) The minimum median width of a two-lane,two-way ramp is not less than that requiredfor traffic control devices and their respectiveclearances.

(4) Minimum ditch depth is 0.6 m for designspeeds over 40 mph and 0.45 m for designspeeds of 40 mph or less. Rounding may bevaried to fit drainage requirements whenminimum ditch depth is 0.6 m.

Height of fill/depth Slope notof ditch (m) steeper than (7)

0 - 3 1 : 6

3 - 6 1 : 4

6 - 9 1 : 3 (5)

over 9 1 : 2 (5) (9)

Fill and Ditch Slope Selection

Slope notHeight of cut (m) steeper than

0 - 1.5 1 : 6

1.5 - 6 1 : 3

over 6 1 : 2 (8)

Cut slope Selection (10)

(5) Widen and round foreslopes steeperthan 1:4 as shown on Figure 640-10b.

(6) Method of drainage pickup to be determinedby the designer.

(7) Where practical, consider flatter slopes forthe greater fill heights and ditch depths.

(8) Cut slopes steeper than 1:2 may be usedwhere favorable soil conditions exist orstepped construction is used. See Chapter700 for clear zone and barrier requirements.

(9) Fill slopes as steep as 1:11/2 may be usedwhere favorable soil conditions exist. SeeChapter 700 for clear zone and barrierrequirements.

(10) This table is for preliminary estimates orwhere no other information is available.Design the final slope as recommendedin the soils or geotechnical report. Do notdisturb existing stable slopes just to meetthe slopes given in this table.

Special DesignThis special design section is to be used only when restrictions (high right of way costs or physicalfeatures that are difficult or costly to correct) require its consideration.

Cement concretecurb

When slopes are 1:4or flatter, 0.6 m wideningand rounding are notrequiredSubgrade slope may be in

opposite direction if leftedge only is embankment

0.15 m min

(6) Drainage required unlessone edge of roadway is inembankment or subjectmaterial is free draining

2%

2%

(2) (1)(1)

0.6m

0.6m

0.6m

0.6m

Design Manual Geometric Cross SectionMay 2001 Metric Version Page 640-15

Traveled Way Width for Two-Way Two-Lane Turning RoadwaysFigure 640-7a

Center line

Edge of shoulder

Edge of

traveled way

PC

R

Edge of shoulder

W

Radius oncenter line of Design traveled

traveled way (m) way width (W) (m)

900 to tangent 7.2

899 7.5

600 7.8

300 8.2

200 8.5

150 8.9

120 9.3

100 9.6

90 9.9

80 10.2

70 10.5

60 11.0

50 11.8

Geometric Cross Section Design ManualPage 640-16 Metric Version May 2001

Traveled Way Width for Two-Way Two-Lane Turning RoadwaysFigure 640-7b

Design Manual Geometric Cross SectionMay 2001 Metric Version Page 640-17

Traveled Way Width for Two-Lane One-Way Turning RoadwaysFigure 640-8a

Radius oncenter line of Design traveled

traveled way (m) way width (W) (m)

900 to tangent 7.2

300 to 899 7.5

299 7.8

150 8.1

100 8.4

60 9.0

50 9.3

40 9.7

30 10.5

Geometric Cross Section Design ManualPage 640-18 Metric Version May 2001

Traveled Way Width for Two-Lane One-Way Turning RoadwaysFigure 640-8b

Design Manual Geometric Cross SectionMay 2001 Metric Version Page 640-19

Traveled Way Width for One-Lane Turning RoadwaysFigure 640-9a

(1) On tangents, the minimum lane width may be reduced to 3.6 m

(2) The width given is for a radius on the outside edge of the traveled way. When the radius is on theinside edge of traveled way, the width may be 5.4 m.

(3) The width given is for a radius on the outside edge of the traveled way. When the radius is on theinside edge of traveled way, the width may be 5.6 m.

(4) The width given is for a radius on the outside edge of the traveled way. When the radius is on theinside edge of traveled way, the width may be 6.2 m.

Design traveledRadius (m) way width (W) (m)

100 to tangent 4.5(1)

99 4.8

80 4.9

60 5.1

50 5.3

40 5.5(2)

30 5.9(3)

20 6.8(4)

Geometric Cross Section Design ManualPage 640-20 Metric Version May 2001

Traveled Way Width for One-Lane Turning RoadwaysFigure 640-9b

Design Manual Geometric Cross SectionMay 2001 Metric Version Page 640-21

Traveled Way Width for One-Lane Turning RoadwaysFigure 640-9c

Geometric Cross Section Design ManualPage 640-22 Metric Version May 2001

Shoulder DetailsFigure 640-10a

Design Manual Geometric Cross SectionMay 2001 Metric Version Page 640-23

Shoulder DetailsFigure 640-10b

(1) Shoulder cross slopes are normally thesame as the cross slopes for adjacent lanes.See 640.04(3) in the text for examples,additional information, and requirements oflocations where it may be desirable to havea shoulder cross slope different than theadjacent lane.

(2) Widening and shoulder rounding outside theusable shoulder is required when foreslopeis steeper than 1:4.

(3) See Chapter 440 for shoulder width.

(4) On divided multilane highways see Figures640-15a through 15c for additional detailsand requirements for median shoulders.

(5) See Chapter 1025 for additional require-ments for sidewalks.

(6) It is preferred that curb not be used on highspeed facilities (posted speed >40 mph).

(7) Paved shoulders are required whereverasphalt concrete curb is placed. Use it onlywhere necessary to control drainage fromroadway runoff. See the Standard Plans foradditional details and dimensions.

(8) When rounding is required, use it uniformlyon all ramps and crossroads, as well as themain roadway.

End rounding on the crossroad just beyondthe ramp terminals and at a similar locationwhere only a grade separation is involved.

(9) When widening beyond the edge of usableshoulder is required for asphalt concretecurb, barrier, or other purposes, additionalwidening for shoulder rounding is notrequired.

(10) See Chapter 710 for required widening forguardrail and concrete barrier.

Geometric Cross Section Design ManualPage 640-24 Metric Version May 2001

Superelevation Rates (10% max)Figure 640-11a

Sup

erel

veva

tion

(%)

Radius (m)

10

Sup

erel

evat

ion

(%)

Radius (m)

10

8

6

4

2

0 500 1000 1500 2000 2500 3000 3500 4000

80 mph70 mph60 mph

50 mph

725

500

334269213

55 mph

169131 98 71 49 31

8

2

4

6

4000 200 600 800 1000 1200 1400 1600

45 mph40 mph35 mph30 mph

25 mph

20 mph

Design Manual Geometric Cross SectionMay 2001 Metric Version Page 640-25

Superelevation Rates (6% max)Figure 640-11b

Su

pere

levati

on

(%

)

80 mph

70 mph

60 mph

55 mph

50 mph

932

625

408

325

255

2

4

6

Radius (m)

0 500 1000 1500 2000 2500 3000 3500 4000

Su

pere

levati

on

(%

)

30 mph

156

117

84

57

36

2

4

6

Radius (m)

0 200 400 600 800 1000 1200 1400 1600

202

35 mph

40 mph

45 mph

25 mph

20 mph

Geometric Cross Section Design ManualPage 640-26 Metric Version May 2001

Superelevation Rates (8% max)Figure 640-11c

Radius (m)

Sup

ere l

evat

ion

(%)

184142107 77 52 33

8

6

4

20002

400 600 800 1000 1200 1400 1600

20 mph

25 mph30 mph

35 mph

40 mph

45 mph

Radius (m)

Sup

ere l

evat

ion

(%)

0 500 1000 1500 2000 2500 3000 3500

816

555

367294232

4000 45002

4

6

8

80 mph

70 mph

60 mph

55 mph50 mph

Design Manual Geometric Cross SectionMay 2001 Metric Version Page 640-27

Superelevation Rates for Turning Roadways at IntersectionsFigure 640-12

CurveRadius Range in Superelevation Rates (%) for Design Speed of:

(m) 15 mph 20 mph 25 mph 30 mph 35 mph 40 mph

15 2 - 10

25 2 - 7 2 - 10

50 2 - 5 2 - 8 4 - 10

70 2 - 4 2 - 6 3 - 8 6 - 10

100 2 - 3 2 - 4 3 - 6 5 - 9 8 - 10

150 2 - 3 2 - 3 3 - 5 4 - 7 6 - 9 9 - 10

200 2 2 - 3 2 - 4 3 - 5 5 - 7 7 - 9

300 2 2 - 3 2 - 3 3 - 4 4 - 5 5 - 6

500 2 2 2 2 - 3 3 - 4 4 - 5

700 2 2 2 2 2 - 3 3 - 4

1000 2 2 2 2 2 2 - 3

Geometric Cross Section Design ManualPage 640-28 Metric Version May 2001

Superelevation Transitions for Highway CurvesFigure 640-13a

S *LB=Basic runoff in meters for Design Speed of:

% 20 mph 25 mph 30 mph 35 mph 40 mph 45 mph 50 mph 55 mph 60 mph 70 mph 80 mph

2 10 10 11 12 13 14 14 15 16 18 20

3 14 15 16 18 19 20 22 23 24 27 30

4 19 20 22 23 25 27 29 31 32 36 40

5 24 25 27 29 32 34 36 38 40 45 50

6 29 31 32 35 38 41 43 46 48 54 60

7 34 36 38 41 44 47 50 54 56 63 70

8 38 41 43 47 50 54 58 61 64 72 80

9 43 46 49 53 57 61 65 69 72 81 90

10 48 51 54 59 63 68 72 77 80 90 100

Min LR 20 25 35 35 40 45 50 50 55 65 70

C = Normal crown (%)S = Superelevation rate (%)N = Number of lanes between pointsW = Width of lane

*Based on one 3.6 m lane between the pivotpoint and the edge of traveled way. When thedistance exceeds 3.6 m use the following equationto the obtain LR:

LR=LB(1+0.13889X)

Where:

X = The distance in excess of 3.6 m between thepivot point and the furthest edge of traveledway, in meters

Design Manual Geometric Cross SectionMay 2001 Metric Version Page 640-29

Superelevation Transitions for Highway CurvesFigure 640-13b

C = Normal crown (%)S = Superelevation rate (%)N = Number of lanes between pointsW = Width of lane

Geometric Cross Section Design ManualPage 640-30 Metric Version May 2001

Superelevation Transitions for Highway CurvesFigure 640-13c

C = Normal crown (%)S = Superelevation rate (%)N = Number of lanes between pointsW = Width of lane

Design Manual Geometric Cross SectionMay 2001 Metric Version Page 640-31

Superelevation Transitions for Highway CurvesFigure 640-13d

C = Normal crown (%)S = Superelevation rate (%)N = Number of lanes between pointsW = Width of lane

Geometric Cross Section Design ManualPage 640-32 Metric Version May 2001

Superelevation Transitions for Highway CurvesFigure 640-13e

C = Normal crown (%)S = Superelevation rate (%)N = Number of lanes between pointsW = Width of lane

Design Manual Geometric Cross SectionMay 2001 Metric Version Page 640-33

Superelevation Transitions for Ramp CurvesFigure 640-14a

Length of transition in meters for Design Speed of:

S 20 mph 25 mph 30 mph 35 mph 40 mph 45 mph 50 mph ≥ 55 mph

(%) LB LT LB LT LB LT LB LT LB LT LB LT LB LT LB LT

2 12 20 13 25 14 35 15 35 16 40 17 45 18 50 20 503 15 20 16 25 17 35 19 35 20 40 22 45 23 50 24 504 18 20 20 25 21 35 22 35 24 40 26 45 27 50 29 505 21 21 23 25 24 35 26 35 28 40 30 45 32 50 34 506 24 24 26 26 27 35 30 35 32 40 34 45 36 50 39 507 27 27 29 29 31 35 33 35 36 40 38 45 41 50 44 508 30 30 32 32 34 35 37 37 40 40 43 45 45 50 48 509 33 33 36 36 38 38 41 41 44 44 47 47 50 50 53 5310 36 36 39 39 41 41 44 44 48 48 51 51 54 54 58 58

Table 2 Pivot Point on Center Line — Curve in Direction Opposite to Normal Pavement Slope

LR=LB*(1+0.13889x) Where: x = width of lane greater than 4.5 m.

WL = width of ramp lane

Length of transition in meters for Design Speed of:

S 20 mph 25 mph 30 mph 35 mph 40 mph 45 mph 50 mph ≥ 55 mph

(%) LB LT LB LT LB LT LB LT LB LT LB LT LB LT LB LT

3 3 20 4 25 4 35 4 35 4 40 5 45 5 50 5 504 6 20 7 25 7 35 8 35 8 40 9 45 9 50 10 505 9 20 10 25 11 35 11 35 12 40 13 45 14 50 15 506 12 20 13 25 14 35 15 35 16 40 17 45 18 50 20 507 15 20 16 25 17 35 19 35 20 40 22 45 23 50 24 508 18 20 20 25 21 35 22 35 24 40 26 45 27 50 29 509 21 21 23 25 24 35 26 35 28 40 30 45 32 50 34 5010 24 24 26 26 27 35 30 35 32 40 34 45 36 50 39 50

Table 1 Pivot Point on Center Line — Curve in Direction of Normal Pavement Slope

Geometric Cross Section Design ManualPage 640-34 Metric Version May 2001

Length of transition in meters for Design Speed of:

S 20 mph 25 mph 30 mph 35 mph 40 mph 45 mph 50 mph ≥ 55 mph

(%) LB LT LB LT LB LT LB LT LB LT LB LT LB LT LB LT

3 6 20 7 25 7 35 8 35 8 40 9 45 9 50 10 504 12 20 13 25 14 35 15 35 16 40 17 45 18 50 20 505 18 20 20 25 21 35 22 35 24 40 26 45 27 50 29 506 24 24 26 26 27 35 30 35 32 40 34 45 36 50 39 507 30 30 32 32 34 35 37 37 40 40 43 45 45 50 48 508 36 36 39 39 41 41 44 44 48 48 51 51 54 54 58 589 42 42 45 45 48 48 52 52 56 56 60 60 63 63 68 68

10 48 48 51 51 54 54 59 59 63 63 68 68 72 72 77 77

Table 3 Pivot Point on Edge of Lane — Curve in Direction of Normal Pavement Slope

Superelevation Transitions for Ramp CurvesFigure 640-14b

Length of transition in meters for Design Speed of:

S 20 mph 25 mph 30 mph 35 mph 40 mph 45 mph 50 mph ≥ 55 mph

(%) LB LT LB LT LB LT LB LT LB LT LB LT LB LT LB LT

2 24 24 26 26 27 35 30 35 32 40 34 45 36 50 39 503 30 30 32 32 34 35 37 37 40 40 43 45 45 50 48 504 36 36 39 39 41 41 44 44 48 48 51 51 54 54 58 585 42 42 45 45 48 48 52 52 56 56 60 60 63 63 68 686 48 48 51 51 54 54 59 59 63 63 68 68 72 72 77 777 54 54 58 58 61 61 66 66 71 71 76 76 81 81 87 878 60 60 64 64 68 68 74 74 79 79 85 85 90 90 96 969 66 66 71 71 75 75 81 81 87 87 93 93 99 99 106 106

10 72 72 77 77 81 81 88 88 95 95 102 102 108 108 116 116

Table 4 Pivot Point on Edge of Lane — Curve in Direction Opposite to Normal Pavement Slope

LR=LB*(1+0.13889x) Where: x = width of lane greater than 4.5 m.

WL = width of ramp lane

Design Manual Geometric Cross SectionMay 2001 Metric Version Page 640-35

For notes, see Figure 640-15c

Divided Highway Median SectionsFigure 640-15a

Geometric Cross Section Design ManualPage 640-36 Metric Version May 2001

For notes, see Figure 640-15c

Divided Highway Median SectionsFigure 640-15b

Design Manual Geometric Cross SectionMay 2001 Metric Version Page 640-37

(1) Designs A and B including Alternate Designs1 and 2 are urban median designs, seeChapter 440 for minimum urban medianwidth.

(2) Locate the pivot point to best suit therequirements of vertical clearances,drainage, and aesthetics.

(3) Pavement slopes generally shall be ina direction away from the median.A crowned roadway section may be usedin conjunction with the depressed medianwhere conditions warrant. See Figure 640-3for additional crown information.

(4) Design B may be used uniformly onboth tangents and horizontal curves. Usealternate designs 1 or 2 when the “roll over”between the shoulder and the inside laneon the high side of a superelevated curveexceeds 8%. Provide suitable transitionsat each end of the curve for the variousconditions encountered in applying thealternate to the basic median design.

Divided Highway Median SectionsFigure 640-15c

(5) Method of drainage pickup to be determinedby the designer.

(6) Median shoulders normally slope in thesame direction and rate as the adjacentthrough lane. When median shoulders areover 1.8 m wide or cement concrete pave-ment is used, median shoulders may slopetoward the median. However, the “roll over”algebraic difference in rate of cross slopeshall not exceed 8%. See figures 640-10aand 10b for additional shoulder details.

(7) See Chapter 440 for minimum shoulderwidth.

(8) Future lane, see Chapter 440 for minimumwidth.

(9) Widen and round foreslopes steeper than1:4 as shown on Figure 640-10b.

(10) Designs C, D, and E are rural mediandesings, see Chapter 440 for minimum ruralmedian widths. Rural median designs maybe used in urban areas when minimum ruralmedian widths can be achieved.

Geometric Cross Section Design ManualPage 640-38 Metric Version May 2001

Roadway Sections in Rock Cuts, Design AFigure 640-16a

Design Manual Geometric Cross SectionMay 2001 Metric Version Page 640-39

Roadway Sections in Rock Cuts, Design BFigure 640-16b

Geometric Cross Section Design ManualPage 640-40 Metric Version May 2001

Roadway Sections With Stepped SlopesFigure 640-17

Design Manual Geometric Cross SectionMay 2001 Metric Version Page 640-41

Bridge End SlopesFigure 640-18a

Bridge End Toe of Slope Lower RoadwayCondition End Slope Rate Treatment (1) Slope Rate

End Piers on Fill Height Rate Posted speed Treatmentof lower roadway.

≤ 10.5 m 1:13/4 > 50 mph Rounding> 10.5 m 1:2(2) ≤ 50 mph No rounding

End Piers in Cut Match lower roadway No rounding, toe at center (4)slope.(3) line of the lower roadway ditch.

Lower Roadway Match lower roadway No rounding, toe at center (4)in Cut slope.(3) line of the lower roadway ditch.

Ends in Partial When the cut depth is When the cut depth is > 2.5 m (4)Cut and Fill > 2.5 m and length is and length is > 30 m, no

> 30 m, match cut slope rounding, toe at center lineof the lower roadway. of the lower roadway ditch.

When the cut depth is When the cut depth is ≤1.5 m (4)≤1.5 m or the length is or the length is ≤30 m, it is≤30 m, it is designers designers choice.choice.

Notes:

(1) See Figure 640-18b

(2) Slope may be 1:13/4 in special cases.

(3) In interchange areas, continuity may require variations.

See 640.07.

Geometric Cross Section Design ManualPage 640-42 Metric Version May 2001

Bridge End SlopesFigure 640-18b

Horizontal Stopping Sight DistanceFigure 650-9

Design Manual Sight DistanceMay 2001 Metric Version Page 650-9

Height of eye: 1070 mmHeight of object: 150 mmLine of sight is normally 610 mm abovecenter line of inside lane at point ofobstruction provided no vertical curveis present in horizontal curve.

S ≤ Length of curveAngle is expressed in degrees

Center of lane

Obstruction orback slope

Line ofsight

Sight distance (S)

Radius

M

0

5

10

15

20

0 500 1000 1500 2000 2500 3000

Curve Radius (m)

Late

ral C

leara

nce to O

bstr

uctio

n, M

(m

)

S=50 m

S=260 m

S=320 m

S=200 mS=140 m

S=100 mS=80 mS=60 m

M R 1 COS28.65 S

R= −

���

���

SR

28.65COS

1 R M

R= − −�

��

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�

�

��

Design Manual Roadside SafetyMay 2001 Metric Version Page 700-1

700 Roadside Safety

700.01 General700.02 References700.03 Definitions700.04 Clear Zone700.05 Hazards to be Considered for

Mitigation700.06 Median Considerations700.07 Other Roadside Safety Features700.08 Documentation

700.01 GeneralRoadside safety addresses the area outside of theroadway and is an important component of totalhighway design. The roadside environment issignificant to safety as illustrated by the fact thatnearly one third of the fatal accidents are singlevehicle run-off-the-road accidents. There arenumerous reasons why a vehicle leaves theroadway. Regardless of the reason, a forgivingroadside can reduce the seriousness of the conse-quences of a roadside encroachment. The idealhighway has roadsides and median areas that areflat and unobstructed by hazards.

Elements such as side slopes, fixed objects, andwater are potential hazards that a vehicle mightencounter when it leaves the roadway. Thesehazards present varying degrees of danger to thevehicle and its occupants. Unfortunately, geogra-phy and economics do not always allow idealhighway conditions. The mitigative measures tobe taken depend on the probability of an accidentoccurring, the likely severity, and the availableresources.

In order of preference, mitigative measures are:removal, relocation, reduction of the impactseverity (using breakaway features or making ittraversable), and shielding with a traffic barrier.Consider cost (initial and life cycle costs) andmaintenance requirements in addition to accidentseverity when selecting a mitigative measure. Usetraffic barriers or earth berms only when othermeasures cannot reasonably be accomplished.See Chapter 710 for additional information ontraffic barriers.

700.02 ReferencesStandard Plans for Road, Bridge, and MunicipalConstruction (Standard Plans), M 21-01,WSDOT

Roadside Manual, M 25-30, WSDOT

Roadside Design Guide, AASHTO

700.03 DefinitionsADT The average daily traffic for the designyear under consideration.

clear run-out area The area at the toe of anonrecoverable slope available for safe use by anerrant vehicle.

clear zone The total roadside border area,starting at the edge of the traveled way, availablefor use by errant vehicles. This area may consistof a shoulder, a recoverable slope, a nonrecover-able slope, and/or a clear run-out area. The clearzone cannot contain a critical slope. DesignClear Zone is the minimum target value usedin highway design.

critical slope A slope on which a vehicle islikely to overturn. Slopes steeper than 1:3 areconsidered critical slopes.

hazard A side slope, a fixed object, or water that,when struck, would result in unacceptable impactforces on the vehicle occupants or place theoccupants in a hazardous position. It can be eithernatural or manmade.

nonrecoverable slope A slope on which anerrant vehicle will continue until it reaches thebottom, without having the ability to recovercontrol. Fill slopes steeper than 1:4, but nosteeper than 1:3, are considered nonrecoverable.

recoverable slope A slope on which a the driverof an errant vehicle can regain control of thevehicle. Slopes of 1:4 or flatter are consideredrecoverable.

recovery area The minimum target value usedin highway design when a fill slope between1:4 and 1:3 starts within the Design Clear Zone

traffic barrier A longitudinal barrier, includingbridge rail or an impact attenuator, used toredirect vehicles from hazards located within anestablished Design Clear Zone, to prevent mediancrossovers, to prevent errant vehicles from goingover the side of a bridge structure, or (occasion-ally), to protect workers, pedestrians, or bicyclistsfrom vehicular traffic.

traveled way The portion of the roadwayintended for the movement of vehicles, exclusiveof shoulders and lanes for parking, turning, andstorage for turning.

700.04 Clear ZoneThe clear zone is a primary consideration whenanalyzing hazards. The intent is to provide asmuch clear, traversable recovery area as practical.The Design Clear Zone values shown in Fig-ure 700-1 are used to judge the adequacy of theexisting clear zone and to provide a minimumtarget value for highway design. These values arenot to be used as justification to compromise ortake away from the existing clear zone.

A Design Clear Zone inventory is required for allprojects indicating evaluate upgrade (EU) or FullDesign Level (F) for the clear zone columns onthe design matrices. (See Chapter 325.) Use theDesign Clear Zone Inventory form (Figure 700-2)to inventory the roadside for potential hazards.Identify the hazards and propose correctiveactions. Eliminating the hazard is the preferredaction. Analyze a roadside hazard to determineif further mitigation is necessary even when itis beyond the values in Figure 700-1.

The Design Clear Zone is a function of theposted speed, side slope, and traffic volume.There are no distances in the table for IV:3H fillslopes. Although fill slopes between IV:4H andIV:3H are considered traversable if free of fixedobjects, these slopes are defined as nonrecover-able slopes. A vehicle may be able to beginrecovery on the shoulder, but will be unable tofurther this recovery until reaching a flatter area

(1:4 or flatter) at the toe of the slope. Underthese conditions, the Design Clear Zone distanceis called a recovery area. The method used tocalculate the recovery area and an example areshown in Figure 700-3.

For ditch sections, the following criteriadetermine the Design Clear Zone:

(a) For ditch sections with foreslopes IV:4H orflatter (see Figure 700-4, Case 1, for an example)the Design Clear Zone distance is the greater of:

1. The Design Clear Zone distance for aIV:10H cut section based on speed and ADT, or

2. A horizontal distance of 1.5 m beyondthe beginning of the back slope.

When a back slope steeper than IV:3H continuesfor 1.5 m beyond the beginning of the back slope(as is the case with a redirectional land form), it isnot necessary to use the IV:10H cut slope criteria.

(b) For ditch sections with foreslopes steeperthan IV:4H, and back slopes steeper than IV:3Hthe Design Clear Zone distance is 3 m horizontalbeyond the beginning of the back slope. (SeeFigure 700-4, Case 2, for an example.)

(c) For ditch sections with foreslopes steeperthan IV:4H and back slopes IV:3H or flatter,the Design Clear Zone distance is the distanceestablished using the recovery area formula(Figure 700-3). (See Figure 700-4, Case 3, foran example.)

700.05 Hazards to be Consideredfor MitigationThere are three general categories of hazards:side slopes, fixed objects, and water. The follow-ing sections provide guidance for determiningwhen these obstacles present a significant hazardto an errant motorist. In addition, several condi-tions require special consideration:

• Locations with high accident histories.

• Locations with pedestrian and bicycle usage.See Chapters 1020, “Bicycle Facilities,” and1025, “Pedestrian Design Considerations.”

Roadside Safety Design ManualPage 700-2 Metric Version May 2001

• Playgrounds, monuments, and other locationswith high social or economic value mayrequire mitigation such as a barrier.

Use of a traffic barrier for obstacles other thanthose described below requires justification in thedesign file.

(1) Side Slopes(a) Fill Slopes. Fill slopes can present a hazardto an errant vehicle with the degree of severitydependant upon the slope and height of the fill.Providing fill slopes that are 1:4 or flatter canmitigate this hazard. If flattening the slope is notfeasible or cost effective, the installation of abarrier may be appropriate. Figure 700-5 repre-sents a selection procedure used to determinewhether a fill side slope constitutes a hazard forwhich a barrier is a cost-effective mitigation.The curves are based on the severity indexes andrepresent the points where total costs associatedwith a traffic barrier are equal to the predictedaccident cost associated with selected slopeheights without traffic barrier. If the ADT andheight of fill intersect on the “Barrier Recom-mended” side of the embankment slope curve,then provide a barrier if flattening the slope isnot feasible or cost effective. Do not use Figure700-5 for slope design. Design guidance forslopes is in Chapters 430 and 640. Also, if thefigure indicates that barrier is not recommendedat an existing nonstandard slope, that result is notjustification for a deviation.

For example, if the ADT is 4000 and theembankment height is 3 m, barrier would be costeffective for a 1:2 slope, but not for a 1:2.5 slope.

This process only addresses the potential hazardof the slope. Obstacles on the slope may com-pound the hazard. Where barrier is not costeffective, use the recovery area formula toevaluate fixed objects on critical slopes lessthan 3 m high.

(b) Cut Slopes. A cut slope is usually less ofa hazard than a traffic barrier. The exception isa rock cut with a rough face that could causevehicle snagging rather than providing relativelysmooth redirection.

Analyze the potential motorist risk and thebenefits of treatment of rough rock cuts locatedwithin the Design Clear Zone. A cost-effective-ness analysis that considers the consequences ofdoing nothing, removal or smoothing of the cutslope, and all other viable options to reduce theseverity of the hazard can be used to determinethe appropriate treatment. Some potentialoptions are:

• Redirectional land form.

• Flexible barrier.

• More rigid barrier.

• Rumble strips.

Conduct an individual investigation for each rockcut or group of rock cuts. Select the most cost-effective treatment.

(2) Fixed ObjectsConsider the following objects for mitigation:

• Wooden poles or posts with cross sectionalarea greater than 10 000 square millimetersthat do not have breakaway features.

• Nonbreakaway steel sign supports.

• Nonbreakaway luminaire supports.

• Trees having a diameter of 100 mm or moremeasured at 150 mm above the groundsurface.

• Fixed objects extending above the groundsurface by more than 100 mm; for example,boulders, concrete bridge rails, piers, andretaining walls.

• Existing nonstandard guardrail (seeChapter 710).

• Drainage items, such as culvert andpipe ends.

Remove objects that are hazards when feasible.Focus on the area within the Design Clear Zonebut do not exclude consideration of objectsoutside this area. The possible mitigative mea-sures are listed below in order of preference.

• Remove.

• Relocate.

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• Reduce impact severity (using a breakawayfeature).

• Shield the object by using redirectionallandform, longitudinal barrier, or impactattenuator.

(a) Trees. When evaluating new plantings orexisting trees, consider the maximum allowablediameter of 100 mm measured at 150 mm abovethe ground when the tree has matured. Whenremoving trees within the Design Clear Zone,complete removal of stumps is preferred. How-ever, to avoid significant disturbance of theroadside vegetation, larger stumps may bemitigated by grinding or cutting them flush tothe ground and grading around them. See theRoadside Management Manual for furtherguidance on the treatment of the disturbedroadside.

(b) Mailboxes. Ensure that all mailboxeslocated within the Design Clear Zone havesupports and connections as shown in the Stan-dard Plans. The standard height of mailboxesfrom the ground to the bottom of the mailbox is1.0 m. This height may vary from 1.0 m to 1.2 mif requested by the mail carrier. Include a note inthe contract plans that gives the height desired ifit is to be different from the standard height. SeeFigure 700-6 for installation guidelines.

In urban areas where sidewalks are prevalent,contact the postal service to determine the mostappropriate mailbox location. Locate mailboxeson access controlled highways in accordancewith Chapter 1420. A turnout, as shown onFigure 700-6, is not required on access controlledfacilities with shoulders of 1.8 m or more whereonly one mailbox is to be installed. On highwayswithout access control, mailboxes must be on theright-hand side of the road in the direction oftravel of the postal carrier. Avoid placing mail-boxes along high-speed, high-volume highways.Locate Neighborhood Delivery and CollectionBox Units (NDCBU) outside the Design ClearZone.

(c) Culvert Ends. Provide a traversable endtreatment when the culvert end section or openingis on the roadway side slope and within theDesign Clear Zone. This can be accomplished for

small culverts by beveling the end to match theside slope, with a maximum of 100 mm extend-ing out of the side slope.

Bars may be necessary to provide a traversableopening for larger culverts. Place bars in theplane of the culvert opening in accordance withthe Standard Plans when:

1. Single cross culvert opening exceeds1000 mm measured parallel to the directionof travel.

2. Multiple cross culvert openings thatexceed 750 mm each, measured parallel tothe direction of travel.

3. Culvert approximately parallel to theroadway has an opening that exceeds 600 mmmeasured perpendicular to the direction oftravel.

Bars are permitted where they will not signifi-cantly affect the stream hydraulics and wheredebris drift is minor. Consult the regional Mainte-nance Office to verify these conditions. If debrisdrift is a concern, consider options to reduce theamount of debris that can enter the pipe (see theHydraulics Manual). Other treatments areextending the culvert to move the end outside theDesign Clear Zone or installing a traffic barrier.

(d) Sign Posts. Whenever possible, locate signsupports behind existing or planned traffic barrierinstallations to eliminate the need for breakawaysupports. Place them at least 7.5 m from the endof the barrier terminal and with the sign facebehind the barrier. When barrier is not presentuse terrain features to reduce the likelihood of anerrant vehicle striking the sign supports. When-ever possible, depending on the type of sign andthe sign message, adjust the sign location to takeadvantage of barrier or terrain features. This willreduce accident potential and, possibly, futuremaintenance costs. See Chapter 820 for addi-tional information regarding the placementof signs.

Sign posts with cross sectional areas greater than10 000 square millimeters that are within theDesign Clear Zone and not located behind abarrier must have breakaway features as shownin the Standard Plans.

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(3) WaterWater with a depth of 0.6 m or more and locatedwith a likelihood of encroachment by an errantvehicle must be considered for mitigation on aproject-by-project basis. Consider the lengthof time traffic is exposed to this hazard and itslocation in relationship to other highwayfeatures such as curves.

Analyze the potential motorist risk and thebenefits of treatment of bodies of water locatedwithin the Design Clear Zone. A cost-effective-ness analysis that considers the consequences ofdoing nothing versus installing a longitudinalbarrier can be used to determine the appropriatetreatment.

700.06 Median ConsiderationsMedians must be analyzed for the potential of anerrant vehicle to cross the median and encounteron-coming traffic. Median barriers are normallyused on access controlled, multilane, high-speed,high traffic volume facilities. These facilitiesgenerally have posted speeds of 50 mph orgreater. Median barrier is not normally placed oncollector highways or other facilities that do nothave controlled access. Providing access throughmedian barrier requires openings and, therefore,end-treatments.

In the absence of cross median accident data, onaccess controlled, high-speed, multilane, hightraffic volume facilities that have relatively flat,unobstructed medians, use Figure 700-7 todetermine if median barrier is warranted.

As indicated in Figure 700-7, the need for medianbarrier is based on a combination of ADT andmedian widths. At low ADTs, the probability ofa vehicle crossing the median is relatively low.Thus, for ADTs less than 20,000, use of medianbarrier is optional. Likewise, for relatively widemedians, the probability of a vehicle crossing themedian is also relatively low. Thus, for medianwidths greater than 10 m, use of median barrieris optional. Consider cable barrier in these widemedians. Median barrier is not recommended formedians wider than 15 m unless there is a historyof across-the-median accidents.

When median barrier is warranted for a medianof less than 1.8 m on an existing facility, medianwidening is required to provide median width of2.4 m. An approved deviation is required for theuse of a median barrier in a median of less than1.8 m.

Consider a wider median when the barrier casts ashadow on the roadway and hinders the meltingof ice. See Chapter 640 for additional criteria forplacement of median barrier. See Chapter 710 forinformation on the types of barriers that can beused. See Chapter 620 for lateral clearance on theinside of a curve to provide the required stoppingsight distance.

When median barrier is being placed in anexisting median, identify the existing crossoversand enforcement observation points. Provide thenecessary median crossovers in accordance withChapter 960, considering enforcement needs.

700.07 Other Roadside SafetyFeatures(1) Rumble StripsRumble strips are grooves or rows of raisedpavement markers placed perpendicular to thedirection of travel to alert inattentive drivers.

There are two kinds of rumble strips:

(a) Roadway rumble strips are placed acrossthe traveled way to alert drivers approaching achange of roadway condition or a hazard thatrequires substantial speed reduction or othermaneuvering. Examples of locations whereroadway rumble strips may be used are inadvance of:

• Stop controlled intersections.

• Port of entry/customs stations.

• Lane reductions where accident historyshows a pattern of driver inattention.

They may also be placed at locations where thecharacter of the roadway changes, such as at theend of a freeway.

Contact the Olympia Service Center DesignOffice for additional guidance on the design andplacement of roadway rumble strips.

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Document justification for using roadway rumblestrips in the project file.

(b) Shoulder rumble strips are placed on theshoulders just beyond the traveled way to warndrivers when they are entering a part of theroadway not intended for routine traffic use.A comparison of rolled-in rumble strips andmilled-in Continuous Shoulder Rumble Strips(CSRS) has determined that CSRS, althoughmore expensive, are more cost effective. CSRSare the standard design.

Rumble strips may be used when an analysisindicates a problem with run-off-the-road acci-dents due to inattentive or fatigued drivers.Consider them on both shoulders of rural dividedhighways. CSRS are required on both the rightand left shoulders of rural Interstate highways.

Lack of required CSRS is a design exception(DE) under any one of the following conditions:

• When another project scheduled within twoyears of the proposed project will overlay orreconstruct the shoulders or will use theshoulders for detours.

• When a pavement analysis determines thatinstalling CSRS will result in inadequateshoulder strength.

• When shoulders will be less than 1.2 m wideon the left and 1.8 m wide on the right.

When CSRS are used, discontinue them where noedge strip is present such as at intersections andwhere curb and gutter are present.

(2) Headlight GlareHeadlight glare from opposing traffic can causesafety problems. Glare can be reduced by the useof wide medians, separate alignments, earthmounds, plants, standard and tall barriers, andby devices known as glare screens specificallydesigned to reduce glare. Consider long termmaintenance when selecting the treatment forglare. When considering earth mound and plant-ing to reduce glare, see the RoadsideManagement Manual for additional guidance.When considering glare screens, see Chapter 620for lateral clearance on the inside of a curve toprovide the required stopping sight distance. In

addition to reducing glare, taller concrete barriersalso provide improved crash performance forlarger vehicles such as trucks.

Glare screen is relatively expensive and its usemust be justified and documented. It is difficult tojustify the use of glare screen where the medianwidth exceeds 6 m, the ADT is less than 20,000vehicles per day, or the roadway has continuouslighting. Consider the following factors whenassessing the need for glare screen:

• Higher rate of night accidents compared tosimilar locations or statewide experience.

• Higher than normal ratio of night to dayaccidents.

• Unusual distribution or concentration ofnighttime accidents.

• Over representation of older drivers in nightaccidents.

• Combination of horizontal and verticalalignment, particularly where the roadway onthe inside of a curve is higher than theroadway on the outside of the curve.

• Direct observation of glare.

• Public complaints concerning glare.

The most common glare problem is betweenopposing main line traffic. Other conditions forwhich glare screen might be appropriate are:

• Between a highway and an adjacent frontageroad or parallel highway, especially whereopposing headlights might seem to be on thewrong side of the driver.

• At an interchange where an on-ramp mergeswith a collector distributor and the ramptraffic might be unable to distinguish betweencollector and main line traffic. In thisinstance, consider other solutions, such asillumination.

• Where headlight glare is a distraction toadjacent property owners. Playgrounds,ball fields, and parks with frequent nighttimeactivities might benefit from screening ifheadlight glare interferes with theseactivities.

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Design Manual Traffic Control SignalsMay 2001 Metric Version Page 850-1

850 Traffic Control Signals

Directive D 55-03, “Responsibility for TrafficControl Devices, Pavement Widening, andChannelization at Existing Intersections andTwo-Way Left Turn Lanes in Cities”

Manual on Uniform Traffic Control Devicesfor Streets and Highways (MUTCD), USDOT,Washington DC, 1988, including the WashingtonState Modifications to the MUTCD, M 24-01,WSDOT, 1996

Plans Preparation Manual, M 22-31, WSDOT

Standard Plans for Road, Bridge, and MunicipalConstruction (Standard Plans), M 21-01,WSDOT

850.03 DefinitionsThe various types of traffic control signals aredefined below. Hazard identification beacons andramp meter signals are energized only at specifictimes. All other signals remain in operation atall times.

conventional traffic signal A permanent ortemporary installation providing alternating rightof way assignments for conflicting traffic move-ments. At least two identical displays are requiredfor the predominant movement on each approach.

emergency vehicle signal A special adaptationof a conventional traffic signal installed to allowfor the safe movement of authorized emergencyvehicles. Usually this type of signal is installedon the highway at the entrance into a fire stationor other emergency facility. The signal assuresprotected entrance onto the highway for theemergency vehicle. When not providing for thismovement, the signal either operates continu-ously, consistent with the requirements for aconventional traffic signal, or displays continuousgreen (allowed at nonintersection locations only).At least two identical displays are required perapproach.

hazard identification beacon A beacon thatsupplements a warning or regulatory sign ormarking. The display is a flashing yellow

850.01 General850.02 References850.03 Definitions850.04 Procedures850.05 Signal Warrants850.06 Conventional Traffic Signal Design850.07 Documentation

850.01 GeneralTraffic control signals are power-operated trafficcontrol devices that warn or direct motorists totake some specific action. More specifically,signals are used to control the assignment of rightof way at locations where conflicts exist or wherepassive devices, such as signs and markings, donot provide the necessary flexibility of controlto move traffic in a safe and efficient manner.

850.02 ReferencesThe following references are used in thedesign, construction, and operation of trafficcontrol signals installed on state highways. TheRevised Codes of Washington (RCWs) notedbelow are specific state laws concerning trafficcontrol signals and conformance to these statutesis required.

RCW 35.77, “Streets-Planning, establishment,construction, and maintenance.”

RCW 46.61.085, “Traffic control signals ordevices upon city streets forming part of statehighways—Approval by department oftransportation.”

RCW 47.24.020 (6) and (13), “Jurisdiction,control.”

RCW 47.36.020, “Traffic control signals.”

RCW 47.36.060, “Traffic devices on countyroads and city streets.”

Washington Administrative Code (WAC)468-18-040, “Design standards for rearrangedcounty roads, frontage roads, access roads,intersections, ramps and crossings.”

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indication. These beacons are not used with“stop”, “yield”, or “do not enter” signs. A hazardidentification beacon is energized only duringthose hours when the hazard or regulation exists.

intersection control beacon (flashing beacon)A secondary control device, generally suspendedover the center of an intersection, that supple-ments intersection warning signs and stop signs.One display per approach may be used but twodisplays per approach are desirable. Intersectioncontrol beacons are installed only at an intersec-tion to control two or more directions of travel.

lane control signal (reversible lanes) A specialoverhead signal that permits, prohibits, or warnsof impending prohibition of lane use.

moveable bridge signal (drawbridge signal)A signal installed to notify traffic to stop whenthe bridge is opened for waterborne traffic.Moveable bridge signals display continuousgreen when the roadway is open to vehiculartraffic.

overlapped displays Overlapped displays allowa nonconflicting traffic movement to run withanother phase. Most commonly, a minor street’sexclusive right-turn phase is overlapped with thenonconflicting major street’s left-turn phase. Anoverlapped display can be terminated after theparent phase terminates. An overlapped displayprogrammed for two or more parent phasescontinues to display until all of the parentphases have terminated.

pedestrian signal An adaptation of a conven-tional traffic signal installed at establishedpedestrian crossings. It is used to create adequategaps in the vehicular movement to allow for safepedestrian crossings. When not operating as apedestrian signal, the system operates consistentwith the requirements for an emergency vehiclesignal.

portable traffic signal A type of conventionaltraffic signal used in work zones to controltraffic. It is typically used on two-way, two-lanehighways where one lane has been closed forroadwork. The traffic signal provides alternatingright of way assignments for conflicting trafficmovements. The signal has an adjustable vertical

support with two three-section signal displaysand is mounted on a mobile trailer with its ownpower source.

ramp meter signal A signal used to control theflow rate of traffic entering a freeway or similarfacility. A minimum of two displays is required.When not in use, ramp meter signals are notenergized.

speed limit sign beacon A beacon installedwith a fixed or variable speed limit sign. Thedisplay is a flashing yellow indication.

stop sign beacon A beacon installed above a stopsign. The display is a flashing red indication.

temporary traffic signal A conventional trafficsignal used during construction to control trafficat an intersection while a permanent signalsystem is being constructed. A temporary trafficsignal is typically an inexpensive span-wireinstallation using timber strain poles.

850.04 Procedures(1) PermitState statutes (RCWs) require Department ofTransportation approval for the design andlocation of all conventional traffic signals andsome types of beacons located on city streetsforming parts of state highways. Approval bythe Department of Transportation for the design,location, installation, and operation of all othertraffic control signals installed on state highwaysis required by department policy.

The Traffic Signal Permit (DOT Form 242-014EF) is the formal record of the department’sapproval of the installation and type of signal.The permit is completed by the responsibleagency and submitted to the Regional Adminis-trator for approval. The region retains a recordof the permit approval, complete with supportingdata, and a copy is forwarded to the State TrafficEngineer at the Olympia Service Center (OSC).Permits are required for the following types ofsignal installations:

• Conventional traffic signals

• Emergency vehicle signals

• Hazard identification beacons, when installedoverhead at an intersection

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• Intersection control beacons

• Lane control signals

• Moveable bridge signals

• Portable signals

• Ramp meter signals

• Pedestrian signals

• Temporary signals

Emergency vehicle signals require annualpermit renewal. The region’s traffic officereviews the installation for compliance withstandards. If satisfactory, the permit is renewedby the Regional Administrator by way of a letterto the operating agency. A copy of this letter isalso sent to the State Traffic Engineer.

Permits are not required for hazard identificationbeacons that are not installed overhead at anintersection, speed limit sign beacons, stop signbeacons, and lane assignment signals at tollfacilities.

When it is necessary to increase the level ofcontrol, such as changing from an intersectioncontrol beacon to a conventional traffic signal, anew permit application is required. If the changeresults in a reduction in the level of control, as inthe case of converting a conventional signal to aflashing intersection beacon, or if the change isthe removal of the signal, submit the “Report ofChange” portion of the traffic signal permit to theRegional Administrator with a copy to the StateTraffic Engineer.

(2) Responsibility for Funding,Construction, Maintenance, andOperationResponsibility for the funding, construction,maintenance, and operation of traffic signals onstate highways has been defined by legislativeaction and transportation commission resolutions.See Figure 850-3. Responsibilities vary depend-ing on location, jurisdiction, and whether or notlimited access control has been established.Limited access as used in this chapter refers tofull, partial, or modified limited access controlas identified in the “Master Plan for LimitedAccess Highways Route Listing”.

(a) Inside the corporate limits of cities with apopulation of less than 22,500. The Departmentof Transportation is responsible for funding,construction, maintenance, and operation oftraffic signals.

(b) Inside the corporate limits of cities with apopulation of 22,500 or greater where there isno established limited access control. The cityis responsible for the funding, construction,maintenance, and operation of traffic signals.

(c) Inside the corporate limits of cities with apopulation of 22,500 or greater where there isestablished limited access control. The Depart-ment of Transportation is responsible for funding,construction, maintenance, and operation oftraffic signals.

(d) Outside the corporate limits of cities andoutside established limited access controlareas. The Department of Transportation isresponsible for funding, construction, mainte-nance, and operation of a signal when a new statehighway crosses an existing county road. TheDepartment of Transportation is responsible foronly the maintenance and operation when a newcounty road intersects an existing state highway.The county is responsible for the constructioncosts of the signal and associated illumination.When it is necessary to construct a traffic signalat an existing county road and state highwayintersection, the construction cost distributionis based on the volume of traffic entering theintersection from each jurisdiction’s roadway.The county’s share of the cost, however, islimited to a maximum of fifty percent. The stateis responsible for maintenance and operation.See WAC 468-18-040 for details.

(e) Outside the corporate limits of cities andinside established limited access control areas.The Department of Transportation is responsiblefor funding, construction, maintenance, andoperation of traffic signals.

(f) Emergency Vehicle Signals. The emer-gency service agency is responsible for all costsassociated with emergency vehicle signals.

(g) Third Party Agreement Signals. At thoselocations where the Department of Transportationis responsible for signals and agrees that the

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proposed signal is justified but where fundingschedules and priorities do not provide for thetimely construction of the signal requested byothers, the following rules apply:

• The third party agrees to design and constructthe traffic signal in conformance with theDepartment of Transportation’s standards.

• The third party agrees to submit thedesign and construction documents to theDepartment of Transportation for reviewand approval.

• The third party obtains a traffic signal permit.

850.05 Signal WarrantsThe requirements for traffic signal warrants arein the MUTCD. A signal warrant is a minimumcondition in which a signal may be installed.Satisfying a warrant does not mandate theinstallation of a traffic signal. The warrantingcondition indicates that an engineering study,including a comprehensive analysis of othertraffic conditions or factors, is required todetermine whether the signal or another improve-ment is justified. There are eleven warrants forconventional traffic signal installations. Thesewarrants are as follows:

• Warrant 1 Minimum vehicular volume

• Warrant 2 Interruption of continuous traffic

• Warrant 3 Minimum pedestrian volume

• Warrant 4 School crossings

• Warrant 5 Progressive movement

• Warrant 6 Accident experience

• Warrant 7 Systems

• Warrant 8 Combination of warrants

• Warrant 9 Four Hour Volumes

• Warrant 10 Peak Hour Delay

• Warrant 11 Peak Hour Volume

Warrants 1, 2, 9, and 11 of the MUTCD allowa reduction in the major street vehicle volumerequirements when the 85th percentile speedexceeds 40 mph. This provision only acknowl-edges a difference in driver behavior on higher

speed roadways. It does not imply that trafficsignals are always the most effective solutionon these facilities. A proposal to install a trafficsignal on any state route with a posted speed of45 mph or higher requires an alternatives analy-sis. See Chapter 910. A proposal to install atraffic signal on a high speed highway requiresOlympia Service Center Design Office reviewand concurrence.

Warrant 6, Accident experience, is used whenthe types of accidents are correctable by theinstallation of a traffic signal. Correctableaccidents typically are angle and side impactcollisions with turning or entering vehicles.

Rear-end, sideswipe, and single vehicle accidentsare usually not correctable with the installationof a traffic signal and are only used in specialcircumstances to satisfy the requirements of theaccident warrant. In the project file, include anexplanation of the conditions justify using thesetypes of accidents to satisfy the accident warrant.

850.06 Conventional Traffic SignalDesign(1) GeneralThe goal of any signal design is to assign rightof way in the most efficient manner possibleand still be consistent with traffic volumes,intersection geometrics, and safety.

(2) Signal PhasingAs a general rule, although there are exceptions,the fewer signal phases the more efficient theoperation of the traffic signal. The number ofphases required for safe, efficient operation isrelated to the intersection geometrics, trafficvolumes, the composition of the traffic flow,turning movement demands, and the level ofdriver comfort desired. The traffic movements atan intersection have been standardized to providea consistent system for designing traffic signals.See Figure 850-4 for standard intersectionmovements, signal head numbering, and thestandard phase operation. Figure 850-5 showsthe phase diagrams for various signal operations.

(a) Level of Service. The efficiency of a trafficsignal is measured differently than highways.While highways use the number and width of

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lanes and other factors to determine capacity anda level of service, traffic signals are measured orrated by the overall delay imposed on the motor-ists. Phase analysis is the tool used to find theanticipated delay for all movements. These delayvalues are then equated to a level of service.There are several computer-based programs fordetermining delay and level of service. Letterdesignations from “A” to “F” denote the levelof service (LOS) with “F” being the worstcondition.

In new construction or major reconstructionprojects where geometric design can be ad-dressed, a level of service of at least “D” in urbanlocations and “C” in rural areas is desirable onstate highways. These levels of service are aprojection of the conditions that will be presentduring the highest peak hour for average trafficvolumes during the design year of the trafficsignal’s operation. Special or seasonal events ofshort duration or holidays, which can generateabnormally high traffic volumes, are not consid-ered in this determination. Provide an explanationin the project file when the desired level ofservice cannot be obtained.

Intersection level of service can be improvedby either adding traffic lanes or eliminatingconflicting traffic movements. Intersections cansometimes be redesigned to compress the interiorof the intersection by eliminating medians,narrowing lanes, or reducing the design vehicleturning path requirements. This compressionreduces the travel time for conflicting movementsand can reduce overall delay.

(b) Left-turn phasing. Left-turn phasing canbe either permissive, protected, or a combinationof both that is referred to as protected/permissive.

1. Permissive left-turn phasing requiresthe left turning vehicle to yield to opposingthrough traffic. Permissive left-turn phasingis used when the turning volume is minor andadequate gaps occur in the opposing throughmovement. This phasing is more effective onminor streets where providing separate,protected turn phasing might cause signifi-cant delays to the higher traffic volume onthe main street. On high speed approaches

or where sight distance is limited, considerproviding a separate left-turn storage lanefor the permissive movement to reduce thefrequency of rear end type accidents and toprovide safe turning movements.

2. Protected/permissive left-turn phasingmeans that the left-turn movements have anexclusive nonconflicting phase followed bya secondary phase when the vehicles arerequired to yield to opposing traffic. Whereleft-turn phasing will be installed and condi-tions do not warrant protected-only operation,consider protected/permissive left-turnphasing. Protected/permissive left-turnphasing can result in increased efficiencyat some types of intersections, particularly“Tee” intersections, ramp terminal intersec-tions, and intersections of a two-way streetwith a one-way street where there are noopposing left movements. Due to the geom-etry of these types of intersections, neitherthe simultaneous display of a circular redindication with a green left-turn arrow nor thecondition referred to as “yellow trap” occur.

“Yellow trap” occurs on a two-way roadwaywhen the permissive left-turn display changesto protected-only mode on one approach,while the display remains in the permissivemode on the opposite approach where a leftturning motorist sees a yellow indication onthe adjacent through movement. The motoristbelieves the opposing through movementalso has a yellow display, when, in fact, thatmovement’s display remains green. It ispossible to prevent “yellow trap” by recallingthe side street, however, this can lead toinefficient operation and is not desirable.

3. Protected left-turn phasing providesthe left turning vehicle a separate phase andconflicting movements are required to stop.

Protected phasing is always required formultilane left-turn movements.

Use protected left-turn phasing when leftturning type accidents on any approach equal3 per year, or 5 in two consecutive years.This includes left turning accidents involvingpedestrians.

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Use protected left-turn phasing when thepeak hour turning volume exceeds the storagecapacity of the turn lane because of insuffi-cient gaps in the opposing through trafficand one or more of the following conditionsare present:

• The 85th percentile speed of the opposingtraffic exceeds 45 mph.

• The sight distance of oncoming traffic isless than 76 m when the 85th percentilespeed is 35 mph or below or less than122 m if the 85th percentile speeds areabove 35 mph.

• The left-turn movement crosses three ormore lanes (including right-turn lanes)of opposing traffic.

• Geometry or channelization is confusing.

Typically, an intersection with protected leftturns operates with leading left turns. Thismeans that on the major street, the left-turnphases, phase 1 and phase 5, time before thethrough movement phases, phase 2 and phase6. On the minor street, the left-turn phases,phase 3 and phase 7, time before phase 4 andphase 8. Lagging left-turn phasing means thatthe through phases time before the conflictingleft-turn phases. In lead-lag left-turn phasingone of the left-turn phases times before theconflicting through phases and the other left-turn phase times after the conflicting throughphases. In all of these cases, the intersectionphasing is numbered in the same manner.Leading, lagging, and lead-lag left-turnphasing are accomplished by changing theorder in which the phases time internallywithin the controller.

(c) Multilane left-turn phasing. Multilaneleft turns can be effective in reducing signaldelay at locations with high left turningvolumes or where the left-turn storage areais limited longitudinally. At locations withclosely spaced intersections, a two-lane left-turn storage area might be the only solutionto prevent the left-turn volume from backingup into the adjacent intersection. Consider theturning paths of the vehicles when proposingmultilane left turns. At smaller intersections

the opposing left turn might not be able toturn during the two-lane left-turn phase andit might be necessary to reposition this lane.If the opposing left turns cannot time togetherthe reduction in delay from the two-lane left-turn phase might be nullified by therequirement for separate opposing left-turnphase. Figure 850-6 shows two examplesof two-lane left with opposing single leftarrangements.

A two-lane exit is required for the two-laneleft-turn movements. In addition, this two-lane exit must extend well beyond theintersection. A lane reduction on this exitimmediately beyond the intersection willcause delays and backups into the intersec-tion because the left turning vehicles move indense platoons and lane changes are difficult.See Chapter 910 for the restrictions on lanereductions on intersection exits.

(d) Right-turn phasing. Right-turnoverlapped phasing can be considered atlocations with a dedicated right-turn lanewhere the intersecting street has a compli-mentary protected left-turn movement andU-turns are prohibited. Several right-turnoverlaps are shown in the Phase Diagrams inFigure 850-5. The display for this movementis dependent on whether a pedestrian move-ment is allowed to time concurrently with thethrough movement adjacent to the right-turnmovement.

For locations with a concurrent pedestrianmovement, use a five section signal headconsisting of circular red, yellow, and greendisplays with yellow and green arrowdisplays. Connect the circular displays tothe through phase adjacent to the right-turnmovement and connect the arrow displays tothe complimentary conflicting minor streetleft-turn phase.

For locations without a concurrent pedestrianmovement, use a three section signal headwith all arrow displays or visibility limitingdisplays (either optically programmedsections or louvered visors) with circular red,yellow arrow, and green arrow displays. Thisdisplay is in addition to the adjacent through

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movement displays. Program this display asan overlap to both the left-turn phase and theadjacent through phase.

(e) Two-lane right-turn phasing. Two-lane right-turn phasing can be used for anextraordinarily heavy right-turn movement.They can cause operation problems when“right turn on red” is permitted at the inter-section. Limited sight distance and incorrectexit lane selection are pronounced and canlead to an increase in accidents. In mostcases, a single unrestricted “right turn only”lane approach with a separate exit lane willcarry a higher traffic volume than thetwo-lane right-turn phasing.

(f) Phasing at railroad crossings.Railroad preemption phasing is required atall signalized intersections when the nearestrail of a railroad crossing is within 61 mof the stop bar of any leg of the intersection,unless the railroad crossing is rarely usedor is about to be abandoned. Preemptionfor intersections with the railroad crossingbeyond 61 m from the intersection stop lineis only considered when the queue on thatapproach routinely occupies the crossing.Contact the railroad company to determineif this line still actively carries freight orpassengers.

Railroad preemption has two distinctintervals; the clearance interval before thetrain arrives and the passage interval whenthe train is crossing the intersection leg.During the clearance interval, all phases areterminated and the movement on the railroadcrossing leg is given priority. When thismovement has cleared the crossing, it is thenterminated. During the passage interval, thetraffic signal cycles between the movementsnot affected by the train crossing. See Figure850-7 for an example of railroad preemptionphasing.

Arranging for railroad preemption requires aformal agreement with the railroad company.The region’s Utilities Engineer’s officehandles this transaction. Contact this officeearly in the design stage as this process can

be time consuming and the railroad companymight require some modifications to thedesign.

(3) Intersection DesignConsiderationsLeft turning traffic can be better accommodatedwhen the opposing left-turn lanes are directlyopposite each other. When a left-turn lane isoffset into the path of the approaching throughlane, the left turning driver might assume that theapproaching vehicles are also in a left-turn laneand fail to yield. To prevent this occurrence, lessefficient split phasing is necessary.

Consider providing an unrestricted through laneon the major street of a “T” intersection. Thisdesign allows for one traffic movement to flowwithout restriction.

Skewed intersections, because of their geometry,are difficult to signalize and delineate. Whenpossible, modify the skew angle to provide morenormal approaches and exits. The large pavedareas for curb return radii at skewed intersections,in many cases, can be reduced when the skewangle is lessened. See Chapter 910 forrequirements and design options.

If roadway approaches and driveways are locatedtoo close to an intersection, the traffic from thesefacilities can affect signal operation. Considerrestricting their access to “Right In / RightOut” operation.

Transit stop and pull out locations can affectsignal operation. See Chapter 1060 for transitstop and pull out designs. When possible, locatethese stops and pull outs on the far side of theintersection for the following benefits:

• Minimizes overall intersection conflict,particularly the right-turn conflict.

• Minimizes impact to the signal operationwhen buses need preemption to pull out.

• Provides extra pavement area where U-turnmaneuvers are allowed.

• Eliminates the sight distance obstruction fordrivers attempting to turn right on red.

• Eliminate conflict with right-turn pockets.

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Large right-turn curb radii at intersectionssometimes have negative impacts on traffic signaloperation. Larger radii allow faster turning speedsand might move the entrance point farther awayfrom the intersection area. See Chapter 910 forguidance in determining these radii.

At intersections with large right-turn radii,consider locating signal standards on raisedtraffic islands to reduce mast arm lengths. Theseislands are primarily designed as pedestrianrefuge areas. See Chapter 1025 for pedestrianrefuge area and traffic island designs.

Stop bars define the point where vehicles muststop to not be in the path of the design vehicle’sleft turn. Check the geometric layout by usingthe turning path templates in Chapter 910 or acomputerized vehicle turning path program todetermine if the proposed phasing can accommo-date the design vehicles. Also, check the turningpaths of opposing left-turn movements. In manycases, the phase analysis might recommendallowing opposing left turns to run concurrently,but the intersection geometrics are such that thisoperation cannot occur.

(4) Crosswalks and PedestriansProvide pedestrian displays and push buttons atall signalized intersections unless the pedestrianmovement is prohibited. Crosswalks, whethermarked or not, exist at all intersections. SeeChapter 1025 for additional information onmarked crosswalks. If a pedestrian movementwill be prohibited at an intersection, providesigning for this prohibition. This signing ispositioned on both the near side and far side onthe street to be visible to the pedestrians. Whenpositioning these signs for visibility, consider thelocation of the stop bar where this crossing willbe prohibited. Vehicles stopped at the stop barmight obstruct the view of the signing. There arenormally three crosswalks at a “T” intersectionand four crosswalks at “four legged” intersection.For pedestrian route continuity the minimumnumber of crosswalks is two at “T” intersectionsand three for “four legged” intersections.

If a crosswalk is installed across the leg whereright or left turning traffic enters, the vehicledisplay cannot have a green turn arrow indication

during the pedestrian “walk” phase. If this cannotbe accomplished, provide a separate pedestrian orvehicle turn phase.

Locate crosswalks as close as possible to theintersection, this improves pedestrian visibilityfor the right-turning traffic. Locate the pushbuttons no more than 1.5 m from the normaltravel path of the pedestrian. Locate the pushbutton no more than 4.5 m from the center point atthe end of the associated crosswalk. At curb andsidewalk areas, locate the pedestrian push buttonsadjacent to the sidewalk ramps to make themaccessible to people with disabilities. Figures850-8a and 850-8b show examples of the pushbutton locations at raised sidewalk locations.When the pedestrian push buttons are installed onthe vehicle signal standard, provide a paved path,not less than 1.2 m in width, from the shoulder orsidewalk to the standard. If access to the signalstandard is not possible, install the push buttonson Type PPB push button posts or on Type PSpedestrian display posts. When pedestrian pushbuttons are installed behind guardrail, use TypePPB posts. Position these posts so that the pushbutton is not more than 0.50 m from the face ofthe guardrail.

(5) Control EquipmentController assemblies can be either Type 170controllers or National Electrical ManufacturersAssociation (NEMA) controllers with dual ring;eight vehicle phase, four pedestrian phase, fouroverlap, operational capabilities. From a designperspective, identical operation can be obtainedfrom either controller. Specify the Type 170unless the region’s policy is to use NEMAcontrollers.

In situations where it is necessary to coordinatethe traffic movements with another agency, it isnecessary for one of the agencies to be respon-sible for the operation of the traffic signal,regardless of which agency actually owns andmaintains the signal. This is accomplished bynegotiating an agreement with the other agency.At a new intersection, where the state owns thesignal but another agency has agreed to operatethe signal, the controller must be compatiblewith that agency’s system.

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When Type 170 controllers are used, but it isnecessary to coordinate the state owned andoperated signals with another jurisdiction’ssystem using NEMA controllers, use compatibleNEMA controllers installed in Type 170/332cabinets. Specify a C1 plug connected to aNEMA A, B, C, and D plug adapter for theseinstallations. The Model 210 conflict monitorin the Type 170/332 cabinet can be used with aNEMA controller by changing a switch setting.The Type 12 NEMA conflict monitor is not usedin this configuration. It does not fit in a Type170/332 cabinet and the operation is not compat-ible. When a NEMA cabinet is used, specifyrack-mountings for the loop detector amplifiersand the preemption discriminators.

Coordinate with the region’s electronics techni-cian to determine the optimum controller cabinetlocation and the cabinet door orientation. Thecontroller cabinet is positioned to provide mainte-nance personnel access. At this location, a clearview of the intersection is desirable. Avoidplacing the controller at locations where it mightblock the view of approaching traffic for amotorist turning right on red. Avoid locating thecontroller where flooding might occur or wherethe cabinet might be hit by errant vehicles. Ifpossible, position the controller where it willnot be affected by future highway construction.

If a telephone line connection is desired forremote signal monitoring and timing adjustmentsby signal operations personnel, provide a modemin the controller cabinet and separate conduitsand a junction box between the cabinet and thetelephone line access point.

Vehicle and pedestrian movements are standard-ized to provide uniformity in signal phasenumbering, signal display numbering, preemptionchannel identification, detection numbering, andcircuit identification. The following are generalguidelines for the numbering system:

• Assign phases 2 and 6 to the major streetthrough movements, orienting phase 2 tothe northbound or eastbound direction of themajor street.

• Assign phases 1 and 5 to the major streetprotected left-turn movements.

• Assign phases 4 and 8 to the minor streetthrough movements.

• Assign phases 3 and 7 to the minor streetprotected left-turn movements.

• At “Tee” intersections, assign the movementon the stem of the “Tee” to either phase 4 orphase 8.

• At intersections with four approaches andeach minor street times separately, assignthe minor streets as phase 4 and 8 and noteon the phase diagram that these phases timeexclusively.

• Signal displays are numbered with the firstnumber indicating the signal phase. Signaldisplays for phase 2, for example, are num-bered 21, 22, 23,and so on. If the displayis an overlap, the designation is the letterassigned to that overlap. If the display isprotected/permissive, the display is numberedwith the phase number of the through displayfollowed by the phase number of the left-turnphase. A protected/permissive signal displayfor phase 1 (the left-turn movement) andphase 6 (the compatible through movement),for example, is numbered 61/11. The circularred, yellow, green displays are connected tothe phase 6 controller output and the yellowand green arrow displays are connected to thephase 1 controller output.

• Pedestrian displays and detectors arenumbered with the first number indicatingthe signal phase and the second number aseither an 8 or 9. Pedestrian displays anddetectors 28 and 29, for example, areassigned to phase 2.

• Detection is numbered with the first numberrepresenting the phase. Detection loops forphase 2 detectors are numbered 21, 22, 23,and so on.

• Emergency vehicle detectors are designatedby letters; phase 2 plus phase 5 operationuses the letter “A”, phase 4 plus phase 7 usesthe letter “B”, phase 1 plus phase 6 uses theletter “C”, and phase 3 plus phase 8 uses theletter “D”.

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(6) Detection SystemsThe detection system at a traffic actuated signalinstallation provides the control unit with infor-mation regarding the presence or movement ofvehicles, bicycles, and pedestrians. Vehicledetection systems perform two basic functions:queue clearance and the termination of phases.Depending on the specific intersection character-istics, either of these functions can take priority.The merits of each function are considered anda compromise might be necessary.

The vehicle detection requirements varydepending on the 85th percentile approach speedas follows:

• When the posted speed is below 35 mph,provide stop bar detection from the stopbar to a point 9.1 m to 10.7 m in advance ofthat location. Assign the stop bar loops todetection input “extension” channels. Whencounting loops are installed, calculate thedistance traveled by a vehicle in two secondsat the 85th percentile speed and position theadvance loops at this distance in advance ofthe stop bar.

• When the posted speed is at or above 35 mph,provide advance detection based on the“dilemma zone detection design”. Whereinstalled, stop bar detection extends from thestop bar to a point 9.1 m to 10.7 m in advanceof that location. Stop bar detection is requiredon minor streets. Assign stop bar detection to“call” channels and assign advance detection-to-detection input “extension” channels.

A dilemma occurs when a person is forced tomake a decision between two alternatives. Asapplied to vehicle detection design, this situationoccurs when two vehicles are approaching atraffic signal and the signal indications turnyellow. The motorist in the lead vehicle mustdecide whether to accelerate and risk being hit inthe intersection by opposing traffic or decelerateand risk being hit by the following vehicle.Dilemma zone detection design has been devel-oped to address this problem. This design allowsthe 90th percentile speed vehicle and the 10th

percentile speed vehicle to either clear theintersection safely or decelerate to a completestop before reaching the intersection. The methodof calculating the dilemma zone and the requireddetection loops is shown in Figure 850-9.

A study of the approach speeds at the intersectionis necessary to design the dilemma zone detec-tion. Speed study data is obtained at theapproximate location at or just upstream of thedilemma zone. Only the speed of the lead vehiclein each platoon is considered. Speed study datais gathered during off-peak hours in free-flowconditions under favorable weather conditions.Prior speed study information obtained at thislocation can be used if it is less than one and ahalf years old and driving conditions have notchanged in the area.

When permissive left-turn phasing is installedon the major street with left-turn channelization,include provisions for switching the detectorinput for future protected left-turn phasing.Assign the detector a left-turn detector numberand connect to the appropriate left-turn detectoramplifier. Then specify a jumper connectorbetween that amplifier output and the extensioninput channel for the adjacent through movementdetector. The jumper is removed when the left-turn phasing is changed to protected in the future.

In most cases, electromagnetic induction loopsprovide the most reliable method of vehicledetection. Details of the construction of theseloops are shown in the Standard Plans. Considervideo detection systems for projects that involveextensive stage construction with numerousalignment changes. Video detection functionsbest when the detectors (cameras) are positionedhigh above the intersection. In this position, theeffective detection area can be about ten times themounting height in advance of the camera. Whenvideo detection is proposed, consider using TypeIII signal standards in all quadrants and install thecameras on the luminaire mast arms. High windcan adversely affect the video equipment byinducing vibration in the luminaire mast arms.Areas that experience frequent high winds are notalways suitable for video detection.

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(7) Preemption Systems(a) Emergency vehicle preemption.Emergency vehicle preemption is provided ifthe emergency service agency has an operatingpreemption system. WSDOT is responsible forthe preemption equipment that is permanentlyinstalled at the intersection for new constructionor rebuild projects. The emergency serviceagency is responsible for preemption emitters inall cases. If the emergency agency requestsadditional preemption equipment at an existingsignal, that agency is responsible for all installa-tion costs for equipment installed permanently atthe intersection. These same guidelines apply fora transit agency requesting transit preemption.The standard emergency vehicle system isoptically activated to be compatible with all areaemergency service agency emitters. Approvalby the State Traffic Engineer is required for theinstallation of any other type of emergencyvehicle preemption system.

Optically activated preemption detectors arepositioned for each approach to the intersection.These detectors function best when the approachis straight and relatively level. When theapproach is in a curve, either horizontal orvertical, it might be necessary to install additionaldetectors in or in advance of the curve to provideadequate coverage of that approach. Consider theapproximate speed of the approaching emergencyvehicle and the amount of time necessary forphase termination and the beginning of thepreemption phase when positioning thesedetectors.

(b) Railroad preemption. An approachingtrain is detected either by electrical contactsunder the railroad tracks or by motion sensors.The railroad company installs these devices.The region provides the electrical connectionsbetween the railroad signal enclosure (called abungalow) and the preemption phasing in thetraffic signal controller. A two-conductor cable isused for the electrical connection. The electricalcircuit is connected to a closed “dry” contactusing a normally energized relay. When a train isdetected, the relay opens the circuit to the trafficsignal controller.

Contact the railroad to determine the voltagethey require for this relay. This will determinethe requirements for the isolator at the trafficsignal controller. The railroad company’s signalequipment usually operates at 24 volt DC storagebatteries charged by a 120 volt AC electricalsystem. Conduit crossings under railroad tracksare normally jacked or pushed because openexcavation is rarely allowed. The usual depth forthese crossings is 1.2 m below the tracks butrailroad company requirements can vary. Contactthe company for their requirements. They, also,will need the average vehicle queue clearancetime values in order to finalize the preemptionagreement. These values are shown on Figure850-10.

Flashing railroad signals are usually necessarywhen railroad preemption is installed at a signal-ized intersection. Automatic railroad gates arealso necessary when train crossings are frequentand the exposure factor is high. Chapter 930provides guidance on determining the railroadcrossing exposure factor. Advance signals, signalsupports with displays, are also only installed atlocations with high exposure factors. See Figures850-11a and 850-11b. When the nearest rail at acrossing is within 27 m of an intersection stop baron any approach, provide additional traffic signaldisplays in advance of the railroad crossing. The27-meter distance provides storage for the longestvehicle permitted by statute (23.0 m plus 1.0 mfront overhang and 1.2 m rear overhang) plus a1.8 m down stream clear storage distance.

Light rail transit crossings at signalized intersec-tions also use a form of railroad preemption.Light rail transit makes numerous stops along itsroute, sometimes adjacent to a signalized inter-section. Because of this, conventional railroadpreemption detection, which uses constant speedas a factor, is not effective. Light rail transit usesa type of preemption similar to that used foremergency vehicle preemption.

(c) Transit priority preemption. Signalpreemption is sometimes provided at intersec-tions to give priority to transit vehicles. Themost common form of preemption is the opticallyactivated type normally used for emergencypreemption. This can be included in mobility

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projects, but the transit company assumes allcosts in providing, installing, and maintainingthis preemption equipment. The department’srole is limited to approving preemption phasingstrategies and verifying the compatibility of thetransit company’s equipment with the trafficsignal control equipment.

(8) Signal DisplaysSignal displays are the devices used to conveyright of way assignments and warnings from thecontrol mechanism to the motorists and pedestri-ans. When selecting display configurations andlocations, the most important objective is theneed to present these assignments and warningsto the motorists and pedestrians in a clear andconcise manner. Typical vehicle signal displaysare shown in Figures 850-12a through 850-12e.In addition to the display requirements containedin the MUTCD, the following also apply:

• Always provide two identical indications forthe through (primary) or predominate move-ment, spaced a minimum of 2.4 m apart whenviewed from the center of the approach. Ata tee intersection, select the higher volumemovement as the primary movement andprovide displays accordingly. A green left-turn arrow on a primary display and a greenball on the other primary display do notcomply with this rule.

• Use arrow indications only when the associ-ated movement is completely protected fromconflict with other vehicular and pedestrianmovements. This includes conflict with apermissive left-turn movement.

• Locate displays overhead whenever possibleand in line with the path of the applicablevehicular traffic.

• Locate displays a minimum of 12.2 m(18.3 m desirable) ands a maximum of45.7 m from the stop line.

• Consider installation of a near-side displaywhen the visibility requirements of Table 4-1of the MUTCD cannot be met.

• Use vertical vehicle-signal display config-urations. Horizontal displays are not allowed

unless clearance requirements cannot beachieved with vertical displays. Approval bythe State Traffic Engineer is required for theinstallation of horizontal displays.

• Use 300-mm signal sections for all vehicledisplays except the lower display for apost-mount ramp-meter signal.

• Use all arrow displays for protected left turnswhen the left turn operates independentlyfrom the adjacent through movement.

• When green and yellow arrows are used incombination with circular red for protectedleft turns operating independently from theadjacent through movement, use visibility-limiting displays (either opticallyprogrammed sections or louvered visors).Contact the local maintenance superinten-dent, signal operations office, or trafficengineer to ensure correct programmingof the head.

• Use either a five section cluster arrangement(dog house) or a five section verticalarrangement.

• Use either Type M or Type N mountingsfor vehicle display mountings on mast arms.Provide only one type of mounting for eachsignal system. Mixing mounting types at anintersection is not acceptable except forsupplemental displays mounted on the signalstandard shaft.

• Use backplates for all overhead mounteddisplays.

• Use Type E mountings for pedestriandisplays mounted on signal standard shafts.

• Consider installing supplemental signaldisplays when the approach is in a horizontalor vertical curve and the intersection visibil-ity requirements cannot be met.

The minimum mounting heights for cantileveredmast arm signal supports and span wire installa-tions is 5.0 m from the roadway surface to thebottom of the signal housing or back plate. Thereis also a maximum height for signal displays. Theroof of a vehicle can obstruct the motorist’s viewof a signal display. The maximum heights from

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the roadway surface to the bottom of the signalhousing with 300-mm sections are shown inFigure 850-1.

* Note: The 5 section cluster display is the sameheight as a vertical 3-section signal display.

Signal Display Maximum HeightsFigure 850-1

Install an advanced signalized intersectionwarning sign assembly to warn motorists of asignalized intersection when either of the twofollowing conditions exists:

• The visibility requirements in Table 4-1 ofthe MUTCD are not achievable.

• The 85th percentile speed is 55 mph or higherand the nearest signalized intersection ismore than three kilometers away.

This warning sign assembly consists of a W3-3sign, two continuously flashing beacons, andsign illumination. Locate the sign in advance ofthe intersection in accordance with Table II-1(Condition A) of the MUTCD.

(9) Signal SupportsSignal supports for vehicle displays consist ofmetal vertical shaft standards (Type I), cantile-vered mast arm standards (Type II, Type III, andType SD Signal Standards), metal strain poles(Type IV and Type V Signal Standards), or

timber strain poles. See the Standard Plans.Mast arm installations are preferred because theyprovide greater stability for signal displays inhigh wind areas and reduce maintenance costs.Preapproved mast arm signal standard designsare available with arm lengths up to 19.8 m. Usemast arm standards for permanent installationsunless display requirements cannot be met. Metalstrain poles are allowed when signal displayrequirements cannot be achieved with mast armstandards or the installation is expected to bein place less than 5 years. Timber strain polesupports are generally used for temporary instal-lations that will be in place less than 2 years.

Pedestrian displays can be mounted on the shaftsof vehicle display supports or on individualvertical shaft standards (Type PS). The pushbuttons used for the pedestrian detection systemcan also be mounted on the shafts of other displaysupports or on individual pedestrian push buttonposts. Do not place the signal standard at alocation that blocks pedestrian or wheelchairactivities. Locate the pedestrian push buttonsso they are ADA accessible to pedestrians andpersons in wheelchairs.

Terminal cabinets mounted on the shafts ofmast arm standards and steel strain poles arerecommended. The cabinet provides electricalconductor termination points between the control-ler cabinet and signal displays that allows foreasier construction and maintenance. Terminalcabinets are usually located on the back side ofthe pole to reduce conflicts with pedestrians andbicyclists.

In the placement of signal standards, the primaryconsideration is the visibility of signal faces.Place the signal supports as far as practicablefrom the edge of the traveled way withoutadversely affecting signal visibility. The MUTCDprovides additional guidance for locating signalsupports. Initially, lay out the location for sup-ports for vehicle display systems, pedestriandetection systems, and pedestrian display systemsindependently to determine the optimal locationfor each type of support. If conditions allow andoptimal locations are not compromised, pedes-trian displays and pedestrian detectors can beinstalled on the vehicular display supports.

Maximum Distance Signal Display Height

Vertical 3 section 5.3 m

Vertical 4 section 5.1 m

Vertical 5 section* 5.0 m

Vertical 3 section 5.8 m

Vertical 4 section 5.5 m

Vertical 5 section* 5.1 m

Vertical 3 section 6.4 m

Vertical 4 section 6.0 m

Vertical 5 section* 5.6 m

Vertical 3 section 6.6 m

Vertical 4 section 6.3 m

Vertical 5 section* 6.0 m

Signal displays12.2 m fromthe stop bar

Signal displays16.2 to 45.7 mfrom the stop bar

Signal displays13.7 m fromthe stop bar

Signal displays15.2 m fromthe stop bar

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Another important consideration that caninfluence the position of signal standards is thepresence of overhead and underground utilities.Verify the location of these lines during thepreliminary design stage to avoid costly changesduring construction.

Mast arm signal standards are designed based onthe total wind load moment on the mast arm. Themoment is a function of the XYZ value and thisvalue is used to select the appropriate mast armfabrication plan. The preapproved mast armfabrication plans are listed in the special provi-sions. To determine the XYZ value for a signalstandard, the cross sectional area for each com-ponent mounted on the mast arm is determined.Each of these values is then multiplied by itsdistance from the vertical shaft. These valuesare then totaled to determine the XYZ value.All signal displays and mast arm mounted signs,including street name signs, are included in thiscalculation. The effect of emergency preemptiondetectors and any required preemption indicatorlights are negligible and are not included. Formast arm mounted signs, use the actual sign areato determine the XYZ value. An example of thiscalculation is shown in Figure 850-13. Crosssectional areas for vehicle displays are shown inFigure 850-2.

Signal Display Area

Vertical 3 section 0.85 m2

Vertical 4 section 1.02 m2

Vertical 5 section 1.22 m2

5 section cluster 1.34 m2

Signal Display AreasFigure 850-2

Foundation design is a critical component of thesignal support. A soils investigation is requiredto determine the lateral bearing pressure and thefriction angle of the soil and whether groundwater might be encountered. The XYZ value isused in determining the foundation depth for thesignal standard. Select the appropriate foundationdepth from Figure 850-13. A special foundationdesign for a mast arm signal standard is requiredif the lateral bearing pressure is less than 48 MPa

or the friction angle is less than 26 degrees. Theregional materials group determines if theseunusual soil conditions are present and a specialfoundation design is required. They then sendthis information to the OSC Materials Office forconfirmation. That office forwards the findingsto the OSC Bridge and Structures Office andrequests the special foundation design. TheBridge and Structures Office designs foundationsfor the regions and reviews designs submitted byprivate engineering groups performing work forthe regions.

Steel strain poles are used in span wire installa-tions and are available in a range of pole classes.A pole class denotes the strength of the pole.The loads and resultant forces imposed on strainpoles are calculated and a pole class greater thanthat load is specified. Figures 850-14a and850-14b show the procedure for determining themetal strain pole class and foundation. Figure850-15 shows an example of the method ofcalculation. The foundation depth is a product ofthe pole class and the soil bearing pressure. Aspecial design is required for metal strain pole ortimber strain pole support systems if the spanexceeds 45 m, the tension on the span exceeds31680 N, or the span wire attachment pointexceeds 8.8 m in height. Contact the OSC Bridgeand Structures Office for assistance.

(10) Preliminary Signal PlanDevelop a preliminary signal plan for the projectfile. Include with the preliminary signal plan adiscussion of the problem that is being addressedby the project. Provide sufficient level of detailon the preliminary signal plan to describe allaspects of the signal installation, includingproposed channelization modifications. Use aplan scale of 1:200 and include the followinginformation:

• Stop bars

• Crosswalks

• Left-turn radii, including beginning andending points

• Corner radii, including beginning andending points

• Vehicle detector locations

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• Pedestrian detector locations

• Signal standard types and locations

• Vehicle signal displays

• Pedestrian signal displays

• Phase diagram including pedestrianmovements

• Emergency vehicle preemption requirements

• Illumination treatment

Submit a copy of the preliminary signal planto the State Traffic Engineer for review andcomment. When the proposed traffic signal ison an NHS highway, also submit a copy of thepreliminary signal plan to the Assistant StateDesign Engineer for review and concurrence.After addressing review comments, finalize theplan and preserve as noted in the documentationsection of this chapter. Prepare the contract plansin accordance with the Plans PreparationManual.

If OSC is preparing the contract plans, specifica-tions, and estimates for the project, submit theabove preliminary signal plan with the followingadditional items:

• Contact person.

• Charge numbers.

• Critical project schedule dates.

• Existing utilities, both underground andoverhead.

• Existing intersection layout, if different fromthe proposed intersection.

• Turning movement traffic counts; peak hourfor isolated intersections; and AM, Midday,and PM peak hour counts if there is anotherintersection within 150 m.

• Speed study indicating 90th and 10thpercentile speeds for all approaches.

• Electrical service location, source of power,and utility company connection requirements.

After the plans, specifications, and estimate areprepared, the entire package is transmitted to theregion for incorporation into their contractdocuments.

(11) Electrical Design(a) Circuitry Layout. Consider cost, flexibil-ity, construction requirements, and ease ofmaintenance when laying out the electricalcircuits for the traffic signal system. Minimizeroadway crossings whenever possible.

(b) Junction Boxes. Provide junction boxesat each end of a roadway crossing, where theconduit changes size, where detection circuitsplices are required, and at locations where thesum of the bends for the conduit run equals orexceeds 360°. Signal standard or strain pole basesare not used as junction boxes. In general, locatejunction boxes out of paved areas and sidewalks.Placing the junction boxes within the traveledway is rarely an effective solution and willpresent long-term maintenance problems. Ifthere is no way to avoid locating the junctionbox in the traveled way, use traffic-bearingboxes. Avoid placing junction boxes in areasof poor drainage. In areas where vandalism canbe a problem, consider junction boxes withlocking lids. The maximum conduit capacitiesfor various types of junction boxes are shownin the Standard Plans.

(c) Conduit. Use galvanized steel conduit forall underground raceways for the traffic signalinstallation on state highways. Thick-walledpolyvinyl chloride (Schedule 80 PVC) conduit isused by many local agencies for ease of installa-tion. At existing intersections, where roadwayreconstruction is not proposed, place theseconduits beyond the paved shoulder or behindexisting sidewalks to reduce installation costs.With the exception of the 16 mm conduit forthe service grounding electrode conductor, theminimum size conduit is 27 mm. The minimumsize conduit for installations under a roadwayis 35 mm. Size all conduits to provide 26%maximum conductor fill for new signal installa-tions. A 40% fill area can be used when installingconductors in existing conduits. See Figure850-16 for conduit and signal conductor sizes.

(d) Electrical Service and other components.Electrical service types, overcurrent protection,and other components are covered in Chapter840.

Traffic Control Signals Design ManualPage 850-16 Metric Version May 2001

850.07 DocumentationPreserve the following documents in the projectfile. See Chapter 330.

� All traffic study information used in thesignal analysis.

� A copy of the approved traffic signalpermit.

� A copy of the preliminary signal plan.

� Alternative analysis for traffic signals onhigh speed highways

� Explanation for using normallyuncorrectable accidents to justify atraffic signal

� Explanation of why the desired level ofservice cannot be obtained

Design Manual Traffic Control SignalsMay 2001 Metric Version Page 850-17

Responsibility for FacilitiesFigure 850-3

Responsibility for Various Types of Facilities on State Highways

Area Responsibility Emergency

vehicle signals

Traffic signals,

school signals, &

intersection control

beacons

Reversible lane

signals &

moveable bridge

signals

Cities with Finance ESD (1) State State

less than Construct ESD (1) State State

22,500 Maintain ESD (1) State State

population Operate ESD (1) State State

Cities with Finance ESD (1) City (2) City (2)

22,500 Construct ESD (1) City (2) City (2)

or greater Maintain ESD (1) City (2) City (2)

population Operate ESD (1) City (2) City (2)

Beyond Finance ESD (1) State State

corporate Country (3)

limits Construct ESD (1) State State

Maintain ESD (1) State State

Operate ESD (1) State State

Access Finance ESD (1) State State

control Construct ESD (1) State State

Maintain ESD (1) State State

Operate ESD (1) State State

Notes:

(1) ESD refers to the applicable Emergency Service Department.

(2) State highways without established limited access control. See 850.04(2)b.

(3) See 850.04(2)d.

Traffic Control Signals Design ManualPage 850-18 Metric Version May 2001

Standard Intersection Movements and Head NumbersFigure 850-4

Phases 1, 2, 5, & 6 are

normally assigned

movements to the

major street

Ø3

Ø4

Ø1

Ø2

Ø5

Ø6

Ø7

Ø8

Standard Eight PhaseOperation

48

29 28

89

68

49

69

88

714142

11

61

62

31 81 82

51

21

22

1

5

7

3

2

6

4

8

EV-B

EV-C

EV-A

EV-D

Ma

jor

Str

eet

Minor Street

Legend

EV

Movement

Vehicleheads

Pedestrianhead

Emergencyvehicle

Standard Intersection Movementsand Head Numbers

Barrier

1

5

26

37

4

8

Design Manual Traffic Control SignalsMay 2001 Metric Version Page 850-19

Phase Diagrams — Four Way IntersectionsFigure 850-5

Ø5

Ø6

Ø1

Ø2

Ø3

Ø4

Ø5

Ø6

Ø7

Ø8

Two Phase OperationPermissive lefts

Five Phase OperationMain St. protected lefts

Minor St. permissive lefts

Ø1

Ø2

Ø3

Ø4

Ø5

Ø6

Ø7

Ø8

Legend

Vehicular through movement

Vehicular left turn movement

Pedestrian movement

Vehicular through and left turn

movement

Vehicular overlapped right turn

movement

Eight Phase OperationMain St. protected lagging lefts

Minor St. protected lagging lefts

Eight Phase OperationMain St. protected lead & lag lefts

Minor St. protected lead & lag lefts

Ø2

Ø1

Ø4

Ø3

Ø6

Ø5

Ø8

Ø7

Ø1

Ø2

Ø3

Ø4

Ø6

Ø5

Ø8

Ø7

Eight Phase OperationProtected leading lefts

and overlapped rights

Ø3

Ø4

Ø1

Ø2

Ø7

Ø8

AB

C D

A

B

C

D

Ø3

Ø4

Ø1

Ø2

Ø5

Ø6

Ø7

Ø8

Eight Phase OperationMain St. protected leading lefts

Minor St. protected leading lefts

Six Phase OperationMain St. protected leading lefts

Minor St. split phasing

(Ø4 first, then Ø8)

Ø1

Ø2

Ø3

Ø4

Ø7

Ø5

Ø6

Ø8

Ø1

Ø2

Ø3

Ø4

Ø7

Ø5

Ø6

Ø8

Six Phase OperationAlternate phasing

Main St. protected leading lefts

Minor St. split phasing

Traffic Control Signals Design ManualPage 850-20 Metric Version May 2001

Turn Lane Configuration Preventing Concurrent PhasingDouble Left Turn Channelization

Figure 850-6

Turning path for opposingsingle left turn

Left turn storage laneoffset to clear opposingdouble lefts

Turning paths fortwo lane left turn

Conflict point

Turning paths fortwo lane left turn

Turning path foropposing single left turn

Left turn storage lanenot offset to clearopposing double lefts

Design Manual Traffic Control SignalsMay 2001 Metric Version Page 850-21

Railroad Preemption PhasingFigure 850-7

DO NOT

STOP

ON

TRACKS

STOP

HERE ON

RED

Typical Signal Installation

Adjacent to Railroad

Clearance Phase

before Train ArrivalPhase Sequence During Train Crossing

27 m orless

Blank-out sign

Railroad signal

Pre-signal standard

Conventional signal heads

Optically programmed

signal heads

Traffic Control Signals Design ManualPage 850-22 Metric Version May 2001

Pedestrian Push Button LocationsFigure 850-8a

Sidewalk Ramp

Sidewalk ramp

Signal pole with dual

pedestrian push buttons

Crosswalk - typical

Not more than 3 m

Center of sidewalk landing

Sidewalk ramp

CrosswalksSidewalk ramp

Center of sidewalk

ramp landing

Center of sidewalk

ramp landing

Not more than 3 m

Not more than 3 m

Signal pole with dual

pedestrian push

buttons

Paved area required when

push buttons are more than

0.5 m from edge of sidewalk

Design Manual Traffic Control SignalsMay 2001 Metric Version Page 850-23

Pedestrian Push Button LocationsFigure 850-8b

Crosswalk

Crosswalk

Sidewalk ramp

Sidewalk ramp

Sidewalk landing

Sidewalk landing

Crosswalk

Crosswalk

Sidewalk ramp

Sidewalk ramp

Post with one

pedestrian push

button

Not more than 0.5 m

Sidewalk ramp

landing

Sidewalk ramp

landing

Not more than 0.5 m

Post with one

pedestrian push

button

Post with one

pedestrian push

button

Post with one

pedestrian push

button

Not more than

0.5 m

Not more than

0.5 m

Traffic Control Signals Design ManualPage 850-24 Metric Version May 2001

Dilemma Zone Loop PlacementFigure 850-9

DDZ 10 = Downstream end of dilemma

zone for 10th percentile speed

UDZ 90 = Upstream end of dilemma

zone for 90 th percentile speed

LC 1 = V10 travel time todownstream DDZ10

LC 2 = V10 travel time from 1st

loop to 2nd loop

LC 3 = V10 travel time from

3rd loop to DDZ 10

V90 = 90th pecentile speed in meters per second

V10 = 10th percentile speed in meters per second

Where :

Advance loop

UDZ90

DDZ 10

Dilemma zone

LC 1

Stop bar loop

Single Advance Loop Design

When LC1 is equal to or less than 3 seconds

+ V90V902

16UDZ90 =

V102

40DDZ10 = + V10

UDZ90 - DDZ10LC 1 =

V10

PMID =UDZ 90 + DDZ10

2

UDZ 90 - PMIDLC2 =

V10

1st Advance loop

PMID

Dilemma zone

UDZ 90

DDZ 10 LC 2

Stop bar loop

2nd Advance loop

When LC2 is equal to or less than 3 seconds

Double Advance Loop Design

P1MID

P2 MID

DDZ 10

UDZ 90

Dilemma zone

LC 32nd Advance loop

3rd Advance loop

Stop bar loop 1st Advance loop

Triple Advance Loop Design

When LC2 is greater than 3 seconds

LC3 =P

2MID - DDZ10

V10

P1MID = UDZ 90 - 3V 10

P2MID = UDZ 90 - 6V 10

Design Manual Traffic Control SignalsMay 2001 Metric Version Page 850-25

Railroad Queue ClearanceFigure 850-10

Traffic Signal Railroad Track Clearance Interval Table (Single Track)

Queue Start-Up

Time

Queue

Length

Intersection

Clearance

Start-Up

Time

Queue

Clear Time

Time from PE

start to Q

Time Before

Train

Vehicles Seconds Meters Seconds Seconds Seconds Seconds Seconds

A B C D E F G H

1 3.8 6.1 10 3.8 3.8 13.8 13.8

2 3.1 12.2 10 3.1 6.9 16.9 16.9

3 2.7 18.3 10 2.7 9.6 19.6 18.2

4 2.4 24.4 10 2.4 12.0 22.0 19.3

5 2.2 30.5 10 2.2 14.2 24.2 20.1

6 2.1 36.6 10 2.1 16.3 26.3 20.9

7 2.1 42.7 10 2.1 18.4 28.4 21.6

8 2.1 48.8 10 2.1 20.5 30.5 22.4

9 2.1 54.9 10 2.1 22.6 32.6 23.1

10 2.1 61.0 10 2.1 24.7 34.7 23.9

11 2.1 67.1 10 2.1 26.8 36.8 24.6

12 2.1 73.2 10 2.1 28.9 38.9 25.4

A = Number of Vehicles in the queue.

B = Vehicle startup time.

C = Distance from intersection stop bar to R/R gate or R/R stop bar. For single track, stop bar

is 6.1 m upstream from the nearest rail.

D = Worst Case intersection clearance (5 seconds mainline green/flashing "don't walk" +

5 seconds yellow/all red = 10 seconds).

E = Startup time for each vehicle by position in queue.

F = Cumulative startup time, includes the track approach green time (7 seconds minimum).

G = Total time from railroad relay closure until last car in the queue has cleared the intersection stop

bar. G = D + F

H = Total time from railroad relay closure until last car in the queue is 6.1 m beyond nearest rail.

This assumes a departure speed of 10 mph. H = G ((C-12.2m) ÷ (14.7)

Example: A location where it is 18.3m from stop bar to nearest rail of a single track crossing.

Solution: Enter table at queue length of 24.4m ( 18.3m + 6.1m to RR stop bar). Read 19.3 seconds.

10.0

11.0

12.0

13.0

14.0

15.0

16.0

17.0

18.0

19.0

20.0

21.0

22.0

23.0

24.0

25.0

26.0

27.0

6.1 12.2 18.3 24.4 30.5 36.6 42.7 48.8 54.9 61.0 67.1 73.2

Distance from Stop Line to Train Track in Meters

Tim

e b

efo

re T

rain

in

Seco

nd

s

Traffic Control Signals Design ManualPage 850-26 Metric Version May 2001

Intersections With Railroad CrossingsFigure 850-11a

State Hwy.

State Hwy.

27 m or 27 m or

less less Queue

between

stop bars

Peak hour

R/R Track queue R/R Track Traffic

signal

R/R Signal DO NOT R/R Stop bar

R/R Stop bar STOP

ON

TRACKS

Sign

Railroad Crossing Railroad Crossing

with Low Exposure Factor with High Exposure Factor

(See Chapter 930 for R/R crossing protection guidelines) (See Chapter 930 for R/R crossing protection guidelines)

Design Manual Traffic Control SignalsMay 2001 Metric Version Page 850-27

Intersections With Railroad CrossingsFigure 850-11b

State Hwy.

27.1 m

to

36.6 m

Queue

between

stop bars

R/R Track

R/R Signal DO NOT

R/R Stop bar STOP

ON

TRACKS

Sign

Railroad Crossing more

than 88 Ft from Intersection

Traffic Control Signals Design ManualPage 850-28 Metric Version May 2001

Traffic Signal Display PlacementsFigure 850-12a

Design Manual Traffic Control SignalsMay 2001 Metric Version Page 850-29

Traffic Signal Display PlacementsFigure 850-12b

Traffic Control Signals Design ManualPage 850-30 Metric Version May 2001

Traffic Signal Display PlacementsFigure 850-12c

Design Manual Traffic Control SignalsMay 2001 Metric Version Page 850-31

Traffic Signal Display PlacementsFigure 850-12d

Traffic Control Signals Design ManualPage 850-32 Metric Version May 2001

Traffic Signal Display PlacementsFigure 850-12e

Design Manual Traffic Control SignalsMay 2001 Metric Version Page 850-33

Mast Arm Signal Moment and Foundation DepthsFigure 850-13

Total windload calculation (XYZ)

B2 offset = 6.7 m

B3 offset = 5.5 m

B6 offset = 3.0 m

B11 offset = 1.2 m

B2 sign0.70 m²

B3 signal1.34 m² B6 signal

0.85 m²

B11 sign0.37 m²

signal mast arm

Type 2 signal standard

LEFT TURN

YIELDON GREEN

INFO HIGHWAY

First Then

Determine foundation depth from chart

B2 area X B2 offset

0.70 m² X 6.7 m = 4.69 m³

B3 area X B3 offset

1.34 m² X 5.5 m = 7.37 m³

B6 area X B6 offset

0.85 m² X 3.0 m = 2.55 m³

B11 area X B11 offset

0.37 m² X 1.2 m = 0.44 m³

Total XYZ =15.05 m³

If the lateral bearing pressure is 72 MPaand the XYZ is 15.05 m³,

Then the foundation depth is:

2.5 m ~ 0.9 m round foundation type2.2 m ~ 0.9 m square foundation type2.2 m ~ 1.2 m round foundation type

FOUNDATION DEPTH TABLE

Lateral Foundation XYZ (cubic meters)

Bearing Type Type II, III, and SD mast arm standards

Pressure 17.0 m³ 25.5 m³ 34.0 m³ 42.5 m³ 53.8 m³ 65.2 m³

0.9 m Rd. 3.0 m 3.0 m 3.4 m 3.4 m 4.0 m 4.6 m

48 Mpa 0.9 m Sq. 2.5 m 2.5 m 2.8 m 2.8 m 3.0 m 3.4 m

1.2 m Rd. 2.5 m 2.5 m 2.8 m 2.8 m 3.0 m 3.4 m

0.9 m Rd. 2.5 m 2.5 m 2.8 m 3.4 m 4.0 m 4.6 m

72 Mpa 0.9 m Sq. 2.2 m 2.2 m 2.2 m 2.5 m 2.5 m 2.8 m

1.2 m Rd. 2.2 m 2.2 m 2.2 m 2.5 m 2.5 m 2.8 m

0.9 m Rd. 1.9 m 1.9 m 2.2 m 3.4 m 4.0 m 4.6 m

120 Mpa 0.9 m Sq. 1.9 m 1.9 m 1.9 m 1.9 m 2.2 m 2.2 m

1.2 m Rd. 1.9 m 1.9 m 1.9 m 1.9 m 2.2 m 2.2 m

Traffic Control Signals Design ManualPage 850-34 Metric Version May 2001

Strain Pole and Foundation Selection ProcedureFigure 850-14a

Selection Procedure

1. Determine span length . 2. Calculate the total dead load (P) per span.

Use 178 newtons per signal section and 300 newtons per square meter of sign area.

3. Calculate the average load (G) per span.

G = P/n where (n) is the number of signal head assemblies plus the number of signs.

4. Determine cable tension (T) per span.

Enter the proper chart with the average load (G) and number of loads (n). If (n) is less than minimum (n) allowed on chart, use minimum (n) on chart.

5. Calculate the pole load (PL) per pole. If

only one cable is attached to the pole, the pole load (PL) equals the cable tension (T). If more than one cable is attached, (PL) is obtained by

computing the vector resultant of the (T) values. 6. Select the pole class from the “Foundation

Design Table”. Choose the pole class closest to but greater than the (PL) value.

7. Calculate the required foundation depth (D).

Use the formula: D aDT

S=

Select the table foundation depth (DT) from the “Foundation Design Table”. Lateral soil bearing pressure (S) is measured in pounds per square foot (psf). The formula value (a) is a variable for the cross-sectional shape of the foundation. The values for these shapes are: a = 10.94 for a 0.9 m round foundation a = 9.41 for a 1.2 m round foundation a = 8.97 for a 0.9 m square foundation Round (D) upwards to nearest whole number if 30 mm or greater,

8. Check vertical clearance (5 m minimum)

assuming 8.8 m maximum cable attachment height and 5% minimum span sag.

Notes: A special design by the Bridge and Structures Office is required if: The span length exceeds 45 m. The (PL) value exceeds 31680 N The vertical distance between the base plate and the first cable attachment exceeds 8.8 meters. 1. Charts are based on a cable weight of

44 newtons per meter (18 N/m, cable and conductors, 26 N/m ice). Total dead load (P) includes weight of ice on sign and signal section.

2. On timber strain pole designs, specify two down guy anchors when the (PL) value exceeds 2000 N.

Foundation Design Table

Pole Class Foundation

(Newtons) Depth (DT)

8360 N 1.8 m

11880 N 2.1 m

16820 N 2.4 m

21120 N 2.9 m

24640 N 3.0 m

27720 N 3.4 m

31680 N 3.7 m

Design Manual Traffic Control SignalsMay 2001 Metric Version Page 850-35

Strain Pole and Foundation Selection ProcedureFigure 850-14b

Traffic Control Signals Design ManualPage 850-36 Metric Version May 2001

Example Application:

Determine the following: Cable Tensions (T) Pole Loads (PL) Pole Classes Foundation Depths (D) Step 1. Span lengths given above. Step 2. Calculate (P) and (G) values. Span 1-2, n = 3

7 sections x 178 N/sec = 1246 newtons

560 mm² sign x 0.3 N/mm² = 168 newtons

Total (P) = 1414 newtons G = P/n = 1414/3 = 471 newtons

Span 2-3, n = 4 9 sections x 178 N/sec = 1602 newtons

560 mm² sign x 0.3 N/mm² = 168 newtons

Total (P) = 1770 newtons G = P/n = 1770/4 = 443 newtons

Span 3-4, n =2

7 sections x 178 N/sec = 1246 newtons Total (P) = 1246 newtons

G = P/n = 1246/2 = 623 newtons Span 4-1, n = 3

9 sections x 178 N/sec = 1602 newtons Total (P) = 1602 newtons

G = P/n = 1602/3 = 534 newtons Step 3. Determine (T) values. Span Length G Chart n min n T 1-2 42 m 471 N III 3 4 13400 N 2-3 45 m 443 N III 4 4 12900 N 3-4 30 m 623 N II 2 3 12500 N 4-1 36 m 534 N II 3 3 11100 N Step 4.

Calculate (PL) values by computing the vector resultant of the (T) values.

( )a b c bc A= + −2 2 2 cos

Step 5. Select the pole class from the “Design Table”. Pole Pole Number (PL) Class 1 15846 N 16820 N 2 22183 N 24640 N 3 15466 N 16820 N 4 16717 N 16820 N Step 6. Calculate the required foundation depths. Given: (S) = 48 MPa.

D aDT

S=

Foundation Depths (D) Pole Pole 1 m Rd 1.3 m Rd 1 m Sq No. Class DT (a=10.94) (a=9.41) (a=8.97) 1 16820 N 2.4 m 4.0 m 3.5 m 3.5 m 2 24640 N 3.0 m 5.0 m 4.0 m 4.0 m 3 16820 N 2.4 m 4.0 m 3.5 m 3.5 m 4 16820 N 2.4 m 4.0 m 3.5 m 3.5 m

Strain Pole and Foundation Selection ExampleFigure 850-15

Design Manual Traffic Control SignalsMay 2001 Metric Version Page 850-37

Conduit and Conductor SizesFigure 850-16

Trade Size Inside Diam.

(mm) 26% 40%16 16.05 53 81

21 21.23 92 142

27 27.00 149 229

35 35.41 256 394

41 41.25 347 535

53 52.91 572 879

63 63.22 816 1256

78 78.49 1258 1935

91 90.68 1679 2583

103 102.87 2161 3324

Conduit Sizing TableMaximum Fill (inch² )

Size Area Size Area

(AWG) (mm² ) (AWG) (mm² )# 14 USE 19.4 2cs (# 14) 58.1

# 12 USE 22.6 3cs (# 20) 45.2

# 10 USE 29.0 4cs (# 18) 38.7

# 8 USE 54.8 5c (# 14) 90.3

# 6 USE 67.7 7c (# 14) 109.7

# 4 USE 87.1 10c (# 14) 187.1

# 3 USE 98.1 6pcc (# 19) 206.5

# 2 USE 112.9

Conductor Size Table

Design Manual Intersections At GradeMay 2001 Metric Version Page 910-1

910 Intersections At Grade

Manual on Uniform Traffic Control Devices forStreets and Highways (MUTCD), USDOT,FHWA; including the Washington StateModifications to the MUTCD, M 24-01, WSDOT

Standard Plans for Road, Bridge, and MunicipalConstruction (Standard Plans), M 21-01,WSDOT

Roundabouts: An Informational Guide, FHWA-RD-00-067, USDOT, FHWA

A Policy on Geometric Design of Highways andStreets (Green Book), AASHTO

Highway Capacity Manual (HCM), SpecialReport 209, Transportation Research Board,National Research Council

NCHRP 279Intersection Channelization Design Guide

Highway Research Record No. 211Aspects of Traffic Control Devices, pp 1-18,“Volume Warrants for Left-Turn StorageLanes at Unsignalized Grade Intersections.”Harmelink, M. D.

910.03 Definitionsbulb out A curb and sidewalk bulge or exten-sion out into the roadway used to decrease thelength of a pedestrian crossing. (See chapter1025.)

conflict An event involving two or more roadusers, in which the action of one user causes theother user to make an evasive maneuver to avoida collision.

crossroad The minor roadway at an intersec-tion. At a stopped controlled intersection, thecrossroad has the stop.

intersection angle The angle between anytwo intersectioning legs at the point that thecenter lines intersect.

intersection area The area of the intersectingroadways bounded by the edge of traveled waysand the area of the adjacent roadways to the endof the corner radii, any marked crosswalks

910.01 General910.02 References910.03 Definitions910.04 Design Considerations910.05 Design Vehicle910.06 Right-Turn Corners910.07 Channelization910.08 Roundabouts910.09 U-turns910.10 Sight Distance at Intersections910.11 Traffic Control at Intersections910.12 Interchange Ramp Terminals910.13 Procedures910.14 Documentation

910.01 GeneralIntersections are a critical part of highway designbecause of increased conflict potential. Trafficand driver characteristics, bicycle and pedestrianneeds, physical features, and economics areconsidered during the design stage to developchannelization and traffic control to enhancesafe and efficient multimodal traffic flowthrough intersections.

This chapter provides guidance for designingintersections at grade, including at-grade rampterminals. Guidelines for road approaches are inChapter 920 and interchanges are in Chapter 940.

If an intersection design situation is not coveredin this chapter, contact the Olympic ServiceCenter (OSC) Design Office, for assistance.

910.02 ReferencesAmericans with Disabilities Act of 1990 (ADA)

Washington Administrative Code (WAC)468-18-040, “Design standards for rearrangedcounty roads, frontage roads, access roads,intersections, ramps and crossings”

WAC 468-52, “Highway access management—Access control classification system andstandards”

Local Agency Guidelines (LAG), M 36-63,WSDOT

Intersections At Grade Design ManualPage 910-2 Metric Version May 2001

adjacent to the intersection, or stop bar, but notless than 3 m from the edge of shoulder of theintersecting roadway.

intersection at grade The general area wherea state route or ramp terminal is met or crossedat a common grade or elevation by another stateroute, a county road, or a city street.

four leg intersection An intersection withfour legs, as where two highways cross.

tee (T) intersection An intersection withthree legs in the general form of a “T.”

split tee A four leg intersection with thecross road intersecting the through roadwayat two tee intersections. The crossroad mustbe offset at least the width of the roadway.

wye (Y) intersection An intersection withthree legs in the general form of a “Y” andthe angle between two legs is less than 60°.

intersection leg Any one of the roadwaysradiating from and forming part of anintersection.

entrance leg The lanes of an intersectionleg for traffic entering the intersection.

exit leg The lanes of an intersection leg fortraffic leaving the intersection.

Whether an intersection leg is an entrance legor an exit leg depends on which movement isbeing analyzed. For two way roadways, eachleg is an entrance leg for some movementsand an exit leg for other movements.

intersection sight distance The distance that thedriver of a vehicle on the crossroad can see alongthe through roadway, as compared to the distancerequired for safe operation.

intersection turning radii The geometricdesign of the intersection to allow the designvehicle for each turning movement to completethe turn without encroachment.

island A defined area within an intersection,between traffic lanes, for the separation ofvehicle movements or for pedestrian refuge.It may be outlined with pavement markingsor delineated by curbs. Within an intersection,a median is considered an island.

channelization island An island thatseparates traffic movements into definitepaths of travel and guides traffic into theintended route.

divisional island An island introduced,on an undivided roadway, at an intersectionto warn drivers of the crossroad ahead andregulate traffic through the intersection.

refuge island An island at or near acrosswalk or bicycle path to aid and protectpedestrians and bicyclists crossing theroadway.

median crossover An opening in a medianprovided for crossings by maintenance, lawenforcement, emergency, and traffic servicevehicles. (See Chapter 960.)

roundabout A circular intersection at whichall traffic moves counterclockwise around acentral island. (See IL 4019.01 [Chapter 915])

rural intersection An intersection in anonurban area.

urban intersection An intersection that is inone of the following areas:

• The area within the federal urban areaboundary as designated by FHWA.

• An area characterized by intensive use ofthe land for the location of structures andreceiving such urban services as sewers,water, and other public utilities and servicesnormally associated with urbanized areas.

• An area with not more than twenty-fivepercent undeveloped land.

IntersectionArea

3 m

Design Manual Intersections At GradeMay 2001 Metric Version Page 910-3

910.04 Design ConsiderationsIntersection design requires consideration ofall potential users of the facility. This involvesaddressing the needs of a diverse mix of usergroups including passenger cars, heavy vehiclesof varying classifications, bicycles, and pedestri-ans. Often, meeting the needs of one user grouprequires a compromise in service to others.Intersection design balances these competingneeds, resulting in appropriate levels of operationfor all users.

In addition to reducing the number of conflicts,minimize the conflict area as much as possiblewhile still providing for the required designvehicle (910.05). This is done to control thespeed of turning vehicles and reduce vehicle,bicyclist, and pedestrian exposure.

(1) Traffic AnalysisConduct a traffic analysis and an accidentanalysis to determine the design characteristicsof each intersection. Include recommendationsfor channelization, turn lanes, acceleration anddeceleration lanes, intersection configurations,illumination, bicycle and pedestrian accommo-dations, ADA requirements, and traffic controldevices in the traffic analysis.

(2) Intersection Configurations(a) Intersection angle. An important intersec-tion design characteristic is the intersection angle.The allowable intersection angles are 75° to 105°for new, reconstructed, or realigned intersections.

Existing intersections with an intersection anglebetween 60° and 120° may remain. Intersectionangles outside this range tend to restrict visibility,increase the area required for turning, increasethe difficulty to make a turn, increase the crossingdistance and time for vehicles and pedestrians,and make traffic signal arms difficult orimpossible to design.

(b) Lane alignment. Design intersectionswith entrance lanes aligned with the exit lanes.Do not put angle points on the roadway align-ments within intersection areas or on the throughroadway alignment within 30 m of the edge oftraveled way of a crossroad. This includes shortradius curves where both the PC and PT are

within the intersection area. However, anglepoints within the intersection are allowed atintersections with a minor through movement,such as at a ramp terminal (Figure 910-19).

When practical, locate intersections so that curvesdo not begin or end within the intersection area.

(c) Split Tee. Avoid split tee intersectionswhere there is less than the intersection spacingfor the Highway Access Management Class. See910.04(4). Split tee intersections with an offsetdistance to the left greater than the width of theroadway, but less than the intersection spacing,may be designed with justification. Evaluatethe anticipated benefits against the increaseddifficulty in driving through the intersectionand a more complicated traffic signal design.

Split tee intersections with the offset to the righthave the additional disadvantages of overlappingleft-turns, increased possibility of wrong waymovements, and traffic signal design that iseven more complicated. Do not design a splittee intersection with an offset to the right lessthan the intersection spacing for the class unlesstraffic is restricted to right-in right-out only.

(d) Other Nonstandard Configurations.Do not design intersections with nonstandardconfigurations such as:

• Intersections with offset legs.

• Intersections with more than four legs.

• Tee intersections with the major trafficmovement making a turn.

• Wye intersections that are not a one-waymerge or diverge.

A roundabout may be an alternative to thesenonstandard configurations. (See 910.08 andIL 4019.01 [Chapter 915].)

(3) CrossroadsWhen the crossroad is a city street or countyroad, design the crossroad crossroad beyondthe intersection area according to the applicablestandards shown in:

• Chapter 468-18 WAC.

• The LAG manual.

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• The standards of the local agency that will berequested to accept the facility.

When the crossroad is a state facility, designthe crossroad according to the applicable designlevel and functional class (Chapters 325, 430,and 440). Continue the cross slope of the throughroadway shoulder as the grade for the crossroad.Use a vertical curve that is at least 18 m long toconnect to the grade of the crossroad.

In areas that experience accumulations of snowand ice and for all legs that will require traffic tostop, design a maximum grade of ±4 percent fora length equal to the anticipated queue length forstopped vehicles.

(4) Intersection SpacingAdequate intersection spacing is required toprovide for safety and the desired operationalcharacteristics for the highway. Provide enoughspace between intersections for left-turn lanesand storage length. Space signalized intersec-tions, and intersections expected to be signalized,to maintain efficient signal operation. It isdesirable to space intersections so that queueswill not block an adjacent intersection.

The minimum spacing for highways withlimited access control is covered in Chapter 1420.For other highways, the minimum spacing isdependent on the Highway Access ManagementClass. Figure 910-1 gives the minimum spacingbetween intersections for each Highway AccessManagement Class.

Highway Access IntersectionManagement Class Spacing (m)

1 1610

2 805

3(1) 805

4(1) 805

5(1) 403

(1)Spacing is for rural intersections and urbanintersections that might require signalization.

Minimum Intersection SpacingFigure 910-1

A deviation for less than the minimum spacingin Figure 910-1 will be considered only when noreasonable alternative access exists. For Class 1highways, intersection spacing less than 1/2 miis not permitted (WAC 468-52-040).

910.05 Design VehicleThe physical characteristics of the design vehiclecontrol the geometric design of the intersection.The following design vehicle types arecommonly used:

DesignSymbol Vehicle Type

P Passenger car, including lightdelivery trucks.

BUS Single unit bus

A-BUS Articulated bus

SU Single unit truck

WB-12 Semitrailer truck, overallwheelbase of 12 m

WB-15 Semitrailer truck, overallwheelbase of 15 m

WB-20 Semitrailer truck, overallwheelbase of 20 m

MH Motor home

P/T Passenger car pulling a campertrailer

MH/B Motor home pulling a boattrailer

Design Vehicle TypesFigure 910-2

The geometric design of an intersection requiresidentifying and addressing the needs of allintersection users. There are competing designobjectives when considering the turning require-ments of the larger design vehicles and thecrossing requirements of pedestrians. To reducethe operational impacts of large design vehicles,turn radii are designed so that large vehicles cancomplete their turn without encroaching on theadjacent lanes at either the entrance or the exit

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legs of the turn. This results in larger radii thatcauses increased pavement areas, longer pedestriancrossing distances, and longer traffic signal arms.

To reduce the intersection area, a smaller designvehicle is used or encroachment on the adjacentsame direction lanes at exit legs of the turn isallowed. This reduces the potential for vehicle/pedestrian conflicts, decreases pedestrian cross-ing distance, and controls speeds of turningvehicles. The negative impacts include capacityreductions and greater speed differences betweenturning vehicles and through vehicles.

Select a design vehicle that is the largest vehiclethat normally uses the intersection. The primaryuse of the design vehicle is to determine turningradius requirements for each leg of the intersec-tion. It is possible for each leg to have a differentdesign vehicle. Figure 910-3 shows the minimumdesign vehicles. As justification to use a smallervehicle, include a traffic analysis showing thatthe proposed vehicle is appropriate.

Intersection Type Design Vehicle

Junction of Major WB-20Truck Routes

Junction of State Routes WB-15

Ramp Terminals WB-15

Other Rural WB-15

Industrial WB-12

Commercial SU(1)(2)

Residential SU(1)(2)

(1)To accommodate pedestrians, the P vehicle maybe used as the design vehicle if justification, with atraffic analysis, is documented.

(2)When the intersection is on a transit or school busroute, use the BUS design vehicle as a minimum.See Chapter 1060 for additional guidance for transitfacilities.

Intersection Design VehicleFigure 910-3

To minimize the disruption to other traffic,design the intersection to allow the designvehicles to make each turning movement

without encroaching on curbs, opposing lanes,or same-direction lanes at the entrance leg. Useturning path templates (Figures 910-7a through7c or templates from another published source)to verify that the design vehicle can make theturning movements.

Encroachment on same-direction lanes of theexit leg and the shoulder might be necessaryto minimize crosswalk distances; however, thismight negatively impact vehicular operations.Document and justify the operational tradeoffsassociated with this encroachment. Whenencroachment on the shoulder is required,increase the pavement structure to supportthe anticipated traffic.

Design each turning movement so the largestvehicle that is anticipated to occasionally use theintersection can make the turn without leaving thepaved shoulders or encroaching on a sidewalk.Use the WB-20 as the largest vehicle at all stateroute to state route junctions. Document andjustify any required encroachment into otherlanes, and any degradation of intersectionoperation.

910.06 Right-Turn CornersThe geometric design of an intersection requiresidentifying and addressing the needs of allintersection users. For the design of right turncorners, there can be competing design objectiveswhen considering the turning requirements of thedesign vehicle and the crossing requirements ofpedestrians. To reduce the operational impacts oflarge trucks, right-turn radii are designed so thatthe truck can complete its turn without encroach-ing on the adjacent lanes at either the entranceor the exit legs of the turn. This results in largercorner radii, increased pavement area and pedes-trian crossing distance, a larger conflict area, andhigher vehicle turning speeds.

When pedestrian issues are a primary concern,the design objectives become one of reducingthe potential for vehicle/pedestrian conflicts.This is done by minimizing pedestrian crossingdistance and controlling speeds of turningvehicles. This normally leads to right-cornerdesigns with smaller turning radii. The negative

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impacts include capacity reductions and greaterspeed differences between turning vehicles andthrough vehicles.

Pedestrian refuge islands can also improvepedestrian safety. Pedestrian refuge islandsminimize the crossing distance, reduce theconflict area, and minimize the impacts onvehicular traffic. When designing islands, speedscan be reduced by designing the turning roadwaywith a taper or large radius curve at the beginningof the turn and a small radius curve at the end.This allows larger islands while forcing theturning traffic to slow down.

Figure 910-8 shows right-turn corner designsfor the design vehicles. These are consideredthe minimum pavement area to accommodatethe design vehicles without encroachment onthe adjacent lane at either leg of the curve.

With justification, right-turn corner designs givenin Figure 910-8 may be modified. Document thebenefits and impacts of the modified designincluding: changes to vehicle pedestrian conflicts,vehicle encroachment on the shoulder or adjacentsame direction lane at the exit leg, capacityrestrictions for right-turning vehicles or otherdegradation of intersection operations, and theeffects on other traffic movements. To verify thatthe design vehicle can make the turn, include aplot of the design showing the design vehicleturning path template.

910.07 ChannelizationChannelization is the separation or regulation oftraffic movements into delineated paths of travelto facilitate the safe and orderly movement ofvehicles, bicycles, and pedestrians.

Painted or plastic pavement markings arenormally used to delineate travel paths. (SeeChapter 830 and the standard plans for details.)

(1) Left-Turn LanesLeft-turn lanes provide storage, separate from thethrough lanes, for left-turning vehicles waitingfor a signal to change or for a gap in opposingtraffic. (See 910.07(3) for a discussion on speedchange lanes.)

Design left-turn channelization to providesufficient operational flexibility to functionunder peak loads and adverse conditions.

(a) One-Way Left-Turn Lanes are separatestorage lanes for vehicles turning left from oneroadway onto another. When recommended,one-way left-turn lanes may be an economicalway to lessen delays and accident potentialinvolving left-turning vehicles. In addition, theycan allow deceleration clear of the through trafficlanes. When considering left-turn lanes, considerimpacts to all intersection movements and users.

At signalized intersections, use a traffic signalanalysis to determine if a left-turn lane is neededand what the storage requirements are. (SeeChapter 850.)

At unsignalized intersections, use the followingas a guide to determine whether or not to provideone-way left-turn lanes:

• A traffic analysis indicates that a left-turnlane will reduce congestion. On two-lanehighways, use Figure 910-9a, based on totaltraffic volume (DHV) for both directionsand percent left-turn traffic, to determine iffurther investigation is needed. On four-lanehighways, use Figure 910-9b to determine ifa left-turn lane is recommended.

• An accident study indicates that a left-turnlane will reduce accidents.

• Restrictive geometrics require left-turningvehicles to slow greatly below the speed ofthe through traffic.

• There is less than decision sight distance atthe approach to the intersection.

An HCM analysis may also be used to determineif left-turn lanes are necessary to maintain thedesired level of service.

Determine the storage length required on two-lane highways by using Figures 910-10a through10c. On four-lane highways use Figure 910-9b.These lengths do not consider trucks. Use Figure910-4 for storage length when trucks are present.

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Storage* % Trucks in Left-Turn MovementLength

(ft) 10 20 30 40 50

30 38 38 46 46 46

46 53 61 61 61 61

61 69 76 84 91 91

76 84 91 99 107 114

91 107 114 122 122 122

*Length from Figures 910-9b, 10a, 10b, or 10c.

Left-Turn Storage With Trucks (m)Figure 910-4

Design opposing left-turn vehicle paths witha minimum 1.2 m clearance between opposingturning paths.

Where one-way left-turn channelization withcurbing is to be provided, ensure that surfacewater will drain.

Provide illumination at left-turn lanes inaccordance with the guidelines in Chapter 840.

At signalized intersections with high left-turnvolumes, double left-turn lanes may be neededto maintain the desired level of service. A throatwidth of 9 to 10.8 m is desirable on the exit legof the turn to offset vehicle offtracking and thedifficulty of two vehicles turning abreast. Useturning path templates to verify that the designvehicle can complete the turn. Where the designvehicle is a WB-12 or larger and the truckvolumes are low, consider providing for thedesign vehicle and an SU turning abreast ratherthan two design vehicles turning abreast.

Figures 910-11a through 11d show one-way left-turn geometrics. Figure 910-11a shows wideningto accommodate the new lane. Figures 910-11band 11c show the use of a median.

1. Widening (Figure 910-11a). It isdesirable that offsets and pavement wideningbe symmetrical about the center line or baseline. Where right of way or topographicrestrictions, crossroad alignments, or othercircumstances preclude symmetrical widen-ing, pavement widening may be on oneside only.

2. Divided Highways (Figure 910-11band 11c). Widening is not required for left-turn lane channelization where medians are3.9 m wide or wider. The median accelerationlane shown on the figures can also be pro-vided where the median is 6.9 m or wider.The median acceleration lane might not benecessary at a signalized intersection. Whena median acceleration lane is to be used,design it in accordance with 910.07(3)Speed Change Lanes.

At intersections on divided highways wherechannelized left turn lanes are not provided,consider a minimum protected storage area asshown on Figure 910-11d.

(b) Two-Way Left-Turn Lanes (TWLTL) arelocated between opposing lanes of traffic. Theyare used by vehicles making left turns from eitherdirection, either from or onto the roadway.

Use TWLTLs only in an urban setting wherethere are no more than two through lanes ineach direction. Consider installation of TWLTLswhere:

• An accident study indicates that a TWLTLwill reduce accidents.

• There are closely spaced access points orminor street intersections.

• There are unacceptable through traffic delaysor capacity reductions because of left turningvehicles.

TWLTL can reduce delays to through traffic,reduce rear-end accidents, and provide separationbetween opposing lanes of traffic. However, theydo not provide a safe refuge for pedestrians, cancreate problems with closely spaced accesspoints, and can encourage strip developmentwith closely spaced access points. Considerother alternatives, before using TWLTL, suchas prohibiting midblock left-turns and providingfor U-turns.

The basic design for a TWLTL is illustrated onFigure 910-11e. Additional criteria are:

• The desirable length of a TWLTL is not lessthan 75 m.

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• Provide illumination in accordance with theguidelines in Chapter 840.

• Pavement markings, signs, and other trafficcontrol devices must be in accordance withthe MUTCD and the Standard Plans.

• Provide clear channelization when changingfrom TWLTL to one-way left-turn lanes at anintersection.

(2) Right-Turn Lanes and Drop LanesRight-turn movements influence intersectioncapacity even though there is no conflict betweenright-turning vehicles and opposing traffic. Right-turn lanes might be needed to maintain efficientintersection operation. Use the following asguidelines to determine when to considerright-turn lanes:

• Recommendation from Figure 910-12 basedon same direction approach and right-turntraffic volumes.

• An accident study indicates that a right-turnlane will result in an overall accidentreduction.

• Presence of pedestrians who require right-turning vehicles to stop in the through lanes.

• Restrictive geometrics that require right-turning vehicles to slow greatly below thespeed of the through traffic.

• Less than decision sight distance at theapproach to the intersection.

For unsignalized intersections, see 910.07(3)Speed Change Lanes for guidance on right-turnlane lengths. For signalized intersections, seeChapter 850 to determine if a right-turn lane isneeded and the length requirement.

A capacity analysis may be used to determineif right-turn lanes are necessary to maintain thedesired level of service.

When designing right-turn lanes at signalizedintersections, consider reducing the shoulderwidth to not more than 1.2 m. This reduces thepavement widening for the turn lane and removesthe temptation for vehicles to use the shoulder tobypass the other vehicles in the turn lane.

Where adequate right of way exists, providingright-turn lanes is relatively inexpensive andcan provide increased safety and operationalefficiency.

The right-turn pocket or the right-turn taper(Figure 910-13) may be used at any minorintersection where a deceleration lane is notrequired and turning volumes indicate a needas set forth in Figure 910-12. These designswill cause less interference and delay to thethrough movement by offering an earlier exitto right-turning vehicles.

If the right-turn pocket is used, Figure 910-13shows taper lengths for various posted speeds.

A lane may be dropped at an intersection with aturn-only lane or beyond the intersection with anacceleration lane (Figure 910-14.) Do not allowa lane-reduction taper to cross an intersection orend less than 30 m before an intersection.

When a lane is dropped beyond a signalizedintersection, provide a lane of sufficient lengthto allow smooth merging. For facilities with aposted speed of 45 mph or higher, use a mini-mum length of 450 m. For facilities with a postedspeed less than 45 mph, provide a laneof sufficient length so that the advanced lanereduction warning sign will be placed not lessthan 30 m beyond the intersection area.

(3) Speed Change LanesA speed change lane is an auxiliary laneprimarily for the acceleration or deceleration ofvehicles entering or leaving the through traveledway. Speed change lanes are normally providedfor at-grade intersections on multilane dividedhighways with access control. Where roadsideconditions and right of way allow, speed changelanes may be provided on other through road-ways. Justification for a speed change lanedepends on many factors such as speed, trafficvolumes, capacity, type of highway, the designand frequency of intersections, and accidenthistory.

A deceleration lane is advantageous because,if a deceleration lane is not provided the driverleaving the highway must slow down in thethrough lane regardless of following traffic.

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An acceleration lane is not as advantageousbecause entering drivers can wait for an opportu-nity to merge without disrupting through traffic.

When either deceleration or acceleration lanesare to be used, design them in accordance withFigures 910-14 and 15. When the design speed ofthe turning traffic is greater than 20 mph, designthe speed change lane as a ramp in accordancewith Chapter 940. When a deceleration lane isused with a left-turn lane, add the decelerationlength to the storage length.

(4) IslandsAn island is a defined area within an intersectionbetween traffic lanes for the separation of vehiclemovements or for pedestrian refuge. Within anintersection, a median is considered an island.Design islands to clearly delineate the trafficchannels to drivers and pedestrians.

Traffic islands perform these functions:

• Channelization islands control and directtraffic movement.

• Divisional islands separate trafficmovements.

• Refuge islands provide refuge forpedestrians.

• Islands can provide for the placement oftraffic control devices and luminaires.

• Islands can provide areas within the roadwayfor landscaping.

(a) Size and Shape. Divisional and refugeislands are normally elongated and at least 1.2 mwide and 6 m long. (Mountable curb, used todiscourage turn movements, is not a divisionalisland.)

Channelization islands are normally triangular.In rural areas, 7 m2 is the minimum island areaand 9 m2 is desirable. In urban areas whereposted speeds are 25 mph or less, smaller islandsare acceptable. Use islands with at least 19 m2

if pedestrians will be crossing or traffic controldevices or luminaires will be installed.

Design triangular shaped islands as shown onFigure 910-16a through 16c. The shoulder andoffset widths illustrated are for islands with

barrier curbs. Where painted islands are used,such as in rural areas, these widths are desirablebut may be omitted.

Avoid shoulders wider than 2 m at islandsbecause the wider shoulders can appear to beanother lane.

Island markings may be supplemented withreflective raised pavement markers.

Barrier-free access must be provided at crosswalklocations where raised islands are used. SeeChapter 1025.

(b) Location. Design the approach ends ofislands to provide adequate visibility to alert themotorist of their presence. Position the island sothat a smooth transition in vehicle speed anddirection is attained. Begin transverse lane shiftsfar enough in advance of the intersection to allowgradual transitions. Avoid introducing islands ona horizontal or vertical curve. If the use of anisland on a curve cannot be avoided, provideadequate sight distance, illumination, or exten-sion of the island.

(c) Compound Right-Turn Lane. To designlarge islands, the common method is to use alarge radius curve for the turning traffic. Whilethis does provide a larger island, it also encour-ages higher turning speeds. Where pedestrians area concern, higher turning speeds are undesirable.An alternative is a compound curve with a largeradius followed by a small radius (Figure910-16c). This design forces the turning trafficto slow down.

(d) Curbing. Provide barrier curb for:

• Islands with luminaires, signals, or othertraffic control devices.

• Pedestrian refuge islands.

In addition consider curbing for:

• Divisional and channelizing islands.

• Landscaped islands.

Avoid using curbs if the same objective can beattained with pavement markings.

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Where curbing is to be provided, ensure thatsurface water will drain.

Snow removal operations can be hampered bycurbs and raised islands. Contact the region’sOperations Engineer when considering raisedchannelization in areas of heavy snowfall.

In general, neither mountable nor barrier curbsare used on facilities with a posted speed of45 mph or greater.

910.08 RoundaboutsModern roundabouts are circular intersections.They can be an effective intersection type.

Modern roundabouts differ from the old rotariesand traffic circles in two important respects: theyhave a smaller diameter, which lowers speeds;and they have splitter islands that provide entryconstraints, slowing down the entering speeds.

When well designed, roundabouts are an efficientform of intersection control. They have fewerconflict points, lower speeds, easier decisionmaking, and they require less maintenance. Whenproperly designed and located, they have beenfound to reduce injury accidents, traffic delays,fuel consumption, and air pollution. Roundaboutsalso permit U-turns.

Consider roundabouts at intersections with thefollowing characteristics:

• Where stop signs result in unacceptabledelays for the crossroad traffic. Roundaboutsreduce the delays for the cross road, butincrease the delays for the through roadway.

• With a high left-turn percentage. Unlike mostintersection types, roundabouts can operateefficiently with high volumes of left-turningtraffic.

• With more than four legs. When theintersection cannot be modified by closingor relocating legs, a roundabout can providea solution.

• Where a disproportionately high number ofaccidents involve crossing or turning traffic.

• Where the major traffic movement makesa turn.

• Where traffic growth is expected to be highand future traffic patterns are uncertain.

• Where it is not desirable to give priority toeither roadway.

There are some disadvantages with roundabouts.Roundabouts do not allow for a primary roadwayto have priority because all legs entering aroundabout are treated the same. Also, all trafficentering a roundabout is required to reduce speed.Therefore, roundabouts are not appropriate onhigh speed facilities, where traffic flows areunbalanced, or where an arterial intersects acollector or local road.

See IL 4019.01 [Chapter 915] for informationand requirements on the design of roundabouts.

910.09 U-turnsFor divided highways without full access controlthat have access points where a median preventsleft turns, consider providing locations designedto allow U-turns. Normally, the U-turn opportuni-ties are provided at intersections; however, whereintersections are spaced far apart, considermedian openings between intersections to accom-modate U-turns. Use the desirable U-turn spacing(Figure 910-5) as a guide to determine when toconsider U-turn locations between intersections.When the U-turning volumes are low, use longerspacing.

U-Turn Spacing

Desirable Minimum

Urban(1) 300 m (2)

Suburban 1 km 400 m(3)

Rural 2 km 800 m

(1)For design speeds greater than 45 mph usesuburban spacing.

(2)The minimum spacing is the acceleration lanelength from a stop plus 90 m.

(3)For design speeds greater than 50 mph, theminimum spacing is the acceleration lane length froma stop plus 90 m.

U-Turn SpacingFigure 910-5

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When designing U-turn locations, use Figure910-17 as a guide. Where the median is less than12 m wide and a large design vehicle is required,consider the use of a U-turn roadway.

Document the need for U-turn locations, thespacing used, and justify the selected designvehicle.

910.10 Sight Distance atIntersectionsFor traffic to move safely through intersections,drivers need to be able to see stop signs, trafficsignals, and oncoming traffic in time to reactaccordingly.

Provide decision sight distance, where practical,in advance of stop signs, traffic signals, androundabouts. See Chapter 650 for guidance.

The driver of a vehicle that is stopped, waiting tocross or enter a through roadway, needs obstruc-tion-free sight triangles in order to see enough ofthe through roadway to safely complete all legalmaneuvers before an approaching vehicle on thethrough roadway can reach the intersection. UseFigure 910-18a to determine minimum sightdistance along the through roadway.

The sight triangle is determined as shown inFigure 910-18b. Within the sight triangle, layback the cut slopes and remove, lower, or movehedges, trees, signs, utility poles, and anythingelse large enough to be a sight obstruction.Consider eliminating parking so sight distanceis not obstructed.

The 5.4 m from the edge of traveled way for thesight triangle in Figure 910-18b is for a vehicle3 m from the edge of traveled way. This is theminimum distance for the sight triangle. Whenthe stop bar is placed more than 3 m from theedge of traveled way, consider providing thesight triangle to a point 2.4 m back of the stop bar.

Provide a clear sight triangle for a P vehicle atall intersections. In addition to this, provide aclear sight triangle for the SU vehicle for ruralhighway conditions. If there is significant com-bination truck traffic, use the WB-15 or WB-20rather than the SU. In areas where SU or WB

vehicles are minimal, and right of way restric-tions prohibit adequate sight triangle clearing,only the P vehicle need be considered.

At some intersections, the turning volume froma stop-controlled crossroad is significant enoughto conflict with vehicles on the through roadway.Sight distances shown on Figure 910-6 aredesirable at these intersections. This is the sightdistance required for a P vehicle to turn left orright onto a two-lane highway and attain averagerunning speed without being overtaken by anapproaching vehicle going the same directionat the average running speed.

Design Speed Sight Distance(mph) (m)

25 90

30 115

35 145

40 180

45 225

50 260

60 350

70 475

Sight Distance for Turning VehiclesFigure 910-6

Designs for movements that cross dividedhighways are influenced by the median widths.If the median is wide enough to store the designvehicle, sight distances are determined in twosteps. The first step is for crossing from a stoppedposition to the median storage; the second step isfor the movement, either across, or left into thethrough roadway.

Design ramp terminal sight distance as forat-grade intersections with a turning movement.An added element at ramp terminals is the gradeseparation structure. Figure 910-18b gives thesight distance considerations in the vicinity of astructure. In addition, when the crossroad is anundercrossing, check the sight distance underthe structure graphically using a truck eyeheight of 1830 mm and an object height of 460 mm.

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Document a brief description of the intersectionarea, sight distance restrictions, and trafficcharacteristics to support the design vehicle andsight distances chosen.

910.11 Traffic Control atIntersectionsIntersection traffic control is the process ofmoving traffic safely through areas of potentialconflict where two or more roadways meet.Signs, signals, channelization, and physicallayout are the major tools used to establishintersection control.

There are three objectives to intersection trafficcontrol that can greatly improve intersectionoperations.

• Maximize Intersection Capacity. Sincetwo or more traffic streams cross, converge,or diverge at intersections, capacity of anintersection is normally less than the roadwaybetween intersections. It is usually necessaryto assign right of way through the use oftraffic control devices to maximize capacityfor all users of the intersection. Turn prohibi-tions may be used to increase intersectioncapacity.

• Reduce Conflict Points. The crossing,converging, and diverging of traffic createsconflicts which increase the potential foraccidents involving turning vehicles. Estab-lishing appropriate controls can reduce thepossibility of two cars attempting to occupythe same space at the same time. Pedestrianaccident potential can also be reduced byappropriate controls.

• Priority of Major Streets. Traffic on majorroutes is normally given the right of way overtraffic on minor streets to increase intersec-tion operational efficiency.

If a signal is being considered or exists at anintersection that is to be modified, a preliminarysignal plan is required (Chapter 850). If a newsignal permit is required, it must be approvedbefore the design is approved.

A proposal to install a traffic signal or a round-about on a state route, either NHS or Non-NHS,with a posted speed limit of 45 mph or higherrequires an analysis of alternatives, approved bythe region’s Traffic Engineer with review andcomment by the Olympia Service Center DesignOffice, prior to proceeding with the design.Include the following alternatives in the analysis:

• Channelization, providing deceleration lanes,storage, and acceleration lanes for left- andright-turning traffic.

• Right-off /right-on with U-turn opportunities.

• Grade separation.

• Roundabouts.

• Traffic control signals.

Include a copy of the analysis with the prelimi-nary signal plan or roundabout justification.

910.12 Interchange RampTerminalsThe design to be used or modified for use onone-way ramp terminals with stop or trafficsignal control at the local road is shown onFigure 910-19. Higher volume intersections withmultiple ramp lanes are designed individually.

Due to probable development of large trafficgenerators adjacent to an interchange, width fora median on the local road is desirable wheneversuch development is believed imminent. Thisallows for future left-turn channelization. Usemedian channelization when justified by capacitydetermination and analysis, or by the need toprovide a smooth traffic flow.

Determine the number of lanes for each leg bycapacity analysis methods assuming a trafficsignal cycle, preferably 45 or 60 seconds inlength, regardless of whether a signal is usedor not. Consider all terminals in the analysis.

Adjust the alignment of the intersection legs tofit the traffic movements and to discourage wrongway movements. Use the allowed intersectingangles of 75° to 105° (60° to 120° for modifieddesign level) to avoid broken back or reversecurves in the ramp alignment.

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910.13 ProceduresDocument design considerations and conclusionsin accordance with Chapter 330. For highwayswith access control, see Chapter 1420 for accesscontrol requirements.

(1) ApprovalAn intersection is approved in accordance withChapter 330. When required, the following itemsmust be in the project file before an intersectionmay be approved:

• Traffic analysis

• Deviations approved in accordance withChapter 330

• Preliminary traffic signal plan approved bythe OSC Traffic Office. (See Chapter 850.)

• Intersections with roundabouts require OSCDesign Office approval. See IL 4019.01[Chapter 915] for approval procedures.

(2) Intersection PlansIntersection plans are required for any increasesin capacity (turn lanes) of an intersection, modifi-cation of channelization, or change of intersectiongeometrics. Support the need for intersection orchannelization modifications with history, schoolbus and mail route studies, hazardous materialsroute studies, public meeting comments, andso forth.

Include the following as applicable:

• Drawing of the intersection showing existingand new alignment of the main line andcrossroad.

• Main line stationing of the intersection andangle between intersection legs.

• Curve data on main line and crossroads.

• Right of way lines.

• Location and type of channelization.

• Width of lanes and shoulders on main lineand crossroads (Chapter 440 and 640).

• Proposed access control treatment(Chapter 1420).

• Traffic data including volumes for allmovements and vehicle classifications.

• Classes of highway and design speeds formain line and crossroads (Chapter 440).

• Whether or not the intersection will besignalized or illuminated.

• A copy of all deviations, if any.

(3) Local Agency or DeveloperInitiated IntersectionsThere is a separate procedure for local agencyor developer-initiated projects at intersectionswith state routes. The project initiator submitsan intersection plan, and the documentation ofdesign considerations that led to the plan, to theregion for approval. For those plans requiring adeviation, the deviation must be approved inaccordance with Chapter 330 prior to approvalof the plan. After the plan approval, the regionprepares a construction agreement with theproject initiator. (See the Utilities Manual.)

910.14 DocumentationThe following documents are to be preservedfor future reference in the project file. SeeChapter 330.

� Traffic analyses

� Accident studies

� Split tee intersection evaluation

� Design vehicle selection justifications

� Justification for encroachment on otherlanes

� Largest vehicle documentation andjustification

� Justification for right-turn corner designmodification

� Left-turn lane justification

� Two-way left-turn lane justification

� Right-turn lane justification

� U-turn documentation

� Sight distance documentation

� Approved traffic signal plans

� Intersection plans and supportinginformation

Intersections At Grade Design ManualPage 910-14 Metric Version May 2001

Turning Path TemplateFigure 910-7a

Design Manual Intersections At GradeMay 2001 Metric Version Page 910-15

Turning Path TemplateFigure 910-7b

Intersections At Grade Design ManualPage 910-16 Metric Version May 2001

Turning Path TemplateFigure 910-7c

Design Manual Intersections At GradeMay 2001 Metric Version Page 910-17

Right-Turn CornerFigure 910-8

L1 = Minimum width of the lane that thevehicle is turning from.

L2 = Minimum width of the roadway thatthe vehicle is turning into.

R = Radius to the edge of traveled way.

T = Taper rate (length per unit of widthof widening)

A = Delta angle of the turning vehicle

R

L1 A

L2

1

T

Vehicle A R L1 L2(1) T(2) Vehicle A R L1 L2(1) T(2)

WB-67 60 25.9 3.4 6.7 7 WB-40 60 16.8 3.4 4.6 7.5

75 22.9 3.4 6.4 8 75 16.8 3.4 4.6 7.5

90 21.3 3.4 6.4 8 90 16.8 3.4 4.3 7.5

105 16.8 3.4 7.3 7 105 13.7 3.4 4.9 7.5

120 15.2 3.4 7.3 7 120 13.7 3.4 4.6 7.5

WB-50 60 16.8 3.4 5.8 6 SU All 15.2 3.3 3.3

75 16.8 3.4 5.5 6 P All 10.7 3.3 3.3

90 16.8 3.4 5.2 6

105 15.2 3.4 5.2 6

120 13.7 3.4 5.5 6

(1) At signalized intersections, include all lanes of the exit leg.

(2) When widening is required to obtain the given values of L1 or L2 and no taper rate (T) is given,widen at 25:1.

(3) All distances given in meters and angles in degrees

Intersections At Grade Design ManualPage 910-18 Metric Version May 2001

Left-Turn Storage Guidelines (Two-Lane, Unsignalized)Figure 910-9a

(1) DHV is total volume from both directions.

(2) Speeds are posted speeds.

Design Manual Intersections At GradeMay 2001 Metric Version Page 910-19

Left-Turn Storage Guidelines (Four-Lane, Unsignalized)Figure 910-9b

S = Left-Turn storage length

200

400

600

800

1000

1200

1400

1600

0100500 150 200 250 300 350 400 450 500

Left Turning Volume (DHV)

Op

po

sin

g T

hro

ug

h V

olu

me

(D

DH

V)

Sto

rage n

ot n

eeded

S=3

0 m

S=46 m

S=61 m

S=76 m

S=91 m

Intersections At Grade Design ManualPage 910-20 Metric Version May 2001

Left-Turn Storage Length (Two-Lane, Unsignalized)Figure 910-10a

Design Manual Intersections At GradeMay 2001 Metric Version Page 910-21

Left-Turn Storage Length (Two-Lane, Unsignalized)Figure 910-10b

Intersections At Grade Design ManualPage 910-22 Metric Version May 2001

Left-Turn Storage Length (Two-Lane, Unsignalized)Figure 910-10c

Design Manual Intersections At GradeMay 2001 Metric Version Page 910-23

Median Channelization (Widening)Figure 910-11a

Notes:

(1) The minimum width of the left-turn storagelane (T1+T2) is 3.3 m. The desirable widthis 3.6 m. For left-turn storage length, seeFigures 910-9b for 4-lane roadways or 10athrough 10c for 2-lane roadways.

(2) Use templates for WB-67 design vehicles.

(3) See Standard Plans and MUTCD forpavement marking details.

(4) See Figure 910-8 for right-turn cornerdesign.

W1 = Approaching through lane.

W2 = Departing lane.

T1 = Width of left-turn lane on approach sideof center line.

T2 = Width of left-turn lane on departure sideof center line.

WT = Total width of channelization(W1+W2+T1+T2)

Posted AccelerationSpeed Taper Rate

55 mph 55:1

50 mph 50:1

45 mph 45:1

40 mph 27:1

35 mph 21:1

30 mph 15:1

25 mph 11:1

Table 1

Intersections At Grade Design ManualPage 910-24 Metric Version May 2001

Median Channelization — Median Width 7 m to 8 mFigure 910-11b

Notes:

(1) Lane widths of 3.9 m are desirable for boththe left-turn storage lane and the medianacceleration lane.

(2) For increased storage capacity, consider theleft-turn deceleration taper alternate design.

(3) The minimum total length of the medianacceleration lane is shown in Figure 910-15.

(4) R = 15 m min; use templates for WB-67design vehicles.

(5) See Figure 910-8 for right-turn cornerdesign.

(6) See Table 1, Figure 910-11a for accelerationtape rate.

(7) See Standard Plans and MUTCD forpavement marking details.

Design Manual Intersections At GradeMay 2001 Metric Version Page 910-25

Median Channelization — Median Width of More Than 8 mFigure 910-11c

Notes:

(1) The minimum length of the medianacceleration lane is shown in Figure 910-15.

(2) R = 15 m min. Use templates for WB-67design vehicles.

(3) See Table 1 Figure 910-11a for accelerationtape rate.

(4) See Figure 910-8 for right-turn cornerdesign.

(5) See Standard Plans and MUTCD forpavement marking details.

Intersections At Grade Design ManualPage 910-26 Metric Version May 2001

Median Channelization (Minor Intersection)Figure 910-11d

Notes:

(1) Use templates for WB-67 design vehicle.

(2) See Figure 910-8 for right-turn cornerdesign.

(3) For median width 5.2 m or more. For medianwidth less than 5.2 m, widen to 5.2 m or useFigure 910-11b without median accelerationlane.

(4) See Standard Plans and MUTCD forpavement marking details.

Design Manual Intersections At GradeMay 2001 Metric Version Page 910-27

Median Channelization (Two-Way Left-Turn Lane)Figure 910-11e

Notes:

(1) Use templates for WB-67 design vehicle.

(2) See Figure 910-8 for right-turn cornerdesign.

(3) See the Standard Plans and the MUTCDfor pavement marking details and signingcriteria.

Intersections At Grade Design ManualPage 910-28 Metric Version May 2001

Right-Turn Lane Guidelines(6)

Figure 910-12

100

80

60

40

20

0

0 100 200 300 400 500 600 700

Peak Hour Approach Volume (DDHV) (1)

Peeak H

our

Rig

ht-

turn

Volu

me (

DH

V)

Consider right-turn

lane(5)

Consider right-turn

pocket or taper(4)

Radius only

(1) For two-lane highways, use the peak hour DDHV (through + right-turn).

For multilane, high speed highways (posted speed 45 mph or above), use the right-lane peak hourapproach volume (through + right-turn).

For multilane, low speed highways (posted speed less than 45 mph), there is no traffic volumeright-turn lane or taper requirement.

(2) When all three of the following conditions are met, reduce the right-turn DDHV by 20.

• The posted speed is 45 mph or less

• The right-turn volume is greater than 40 VPH.

• The peak hour approach volume (DDHV) is less than 300 VPH.

(3) See Figure 910-8 for right-turn corner design.

(4) See Figure 910-13 for right-turn pocket or taper design.

(5) See Figure 910-14 for right-turn lane design.

(6) For additional guidance, see 910.07(2) in the text.

Design Manual Intersections At GradeMay 2001 Metric Version Page 910-29

Right-Turn Pocket and Right-Turn TaperFigure 910-13

Posted speed limit L

Below 40 mph 30 m

40 mph or above 50 m

Note: See Figure 910-8 for right-turn corner design.

Intersections At Grade Design ManualPage 910-30 Metric Version May 2001

Right-Turn LaneFigure 910-14

Notes:

(1) For use when the turning traffic is likelyto stop before completing the turn. (Forexample, where pedestrians are present.)

(2) When adjusting for grade, do not deducethe deceleration lane to less than 45 m.

(3) See Figure 910-8 for right-turn cornerdesign.

Highway Turning Roadway designDesign speed (mph)Speed(mph) Stop(1) 15 20

30 75 55(2) 50(2)

40 105 95 85

50 130 120 110

60 160 150 145

70 185 180 175

Minimum Deceleration LaneLength (mph)

Grade Upgrade Downgrade

3% to less 0.9 1.2than 5%

5% or more 0.8 1.35

Adjustment Multiplier forGrades 3% or Greater

Design Manual Intersections At GradeMay 2001 Metric Version Page 910-31

Acceleration LaneFigure 910-15

Notes:

(1) The minimum acceleration lane length forfreeways and expressways is 270 m.

(2) See Figure 910-8 for right-turn cornerdesign.

Highway Turning RoadwayDesign Design Speed (mph)Speed(mph) Stop 15 20

30 55

40 120 100 85

50 195 170 155

60 340 310 290

70 455 430 410

Minimum AccelerationLane Length (ft)

HighwayDesignSpeed % Grade Upgrade Downgrade(mph)

40 3% to 1.3 0.750 less than 1.3 0.6560 5% 1.4 0.670 1.5 0.6

40 1.5 0.650 5% or 1.5 0.5560 more 1.7 0.570 2.0 0.5

Adjustment Multiplier forGrades 3% or Greater

Intersections At Grade Design ManualPage 910-32 Metric Version May 2001

Traffic Island DesignsFigure 910-16a

Notes:

(1) Widen shoulders when adequate right-turnradii or roadway width cannot be providedfor large trucks. Design widened shoulderpavement the same depth as the right-turnlane.

(2) Use the truck turning path templates for thedesign vehicle and a minimum of 0.6 m clear-ance between the wheel paths and the faceof a curb or edge of shoulder to determinethe width of the widened shoulder.

(3) See Chapter 640 for turning roadway widths.

(4) See Figure 910-16c for additional details onisland placement

Design Manual Intersections At GradeMay 2001 Metric Version Page 910-33

Traffic Island Designs (Compound Curve)Figure 910-16b

Notes:

(1) Widen shoulders when adequate right-turn radii and roadwaywidth cannot be provided for large trucks. Design widenedshoulder pavement the same depth as the right-turn lane.

(2) Use the truck turning path templates for the design vehicle anda minimum of 0.6 m clearance between the wheel paths and theface of a curb or edge of shoulder to determine the width of thewidened shoulder.

(3) See Chapter 640 for turning roadway widths.

(4) See Figure 910-16c for additional details on island placement

(5) See Figure 910-8 for right-turn corner design.

Intersections At Grade Design ManualPage 910-34 Metric Version May 2001

Traffic Island DesignsFigure 910-16c

Notes:

(1) See Chapter 440 for minimum shoulderwidth. See the text for additional informationon shoulders at islands.

(2) Provide barrier-free passageways or curbramps when required, see Chapter 1025.

Design Manual Intersections At GradeMay 2001 Metric Version Page 910-35

U-Turn LocationsFigure 910-17

Vehicle W R L F1 F2 T

P 15.6 4.2 4.2 3.6 3.6 —

SU 26.6 9.0 5.9 4.0 4.6 10:1

BUS 26.6 8.5 7.0 4.1 5.5 10:1

WB-40 25.4 7.5 8.0 4.4 6.2 6:1

WB-50 28.4 8.0 9.5 4.9 7.7 6:1

WB-67 28.4 6.8 14.8 4.5 10.5 6:1

MH 25.4 8.0 5.9 4.5 4.9 10:1

P/T 15.6 3.3 3.8 3.6 5.4 6:1

MH/B 31.4 11.0 6.5 4.5 5.0 10:1

U-Turn Design Dimensions (ft)

Notes:

(1) The minimum length of the medianacceleration lane is shown in Figure 910-15.

(2) All dimensions in meters.

(3) When U-turn uses the shoulder, provide3.8 m shoulder width and shoulder pave-ment designed to the same depth as thethrough lanes for the acceleration lengthand taper.

Intersections At Grade Design ManualPage 910-36 Metric Version May 2001

Sight Distance for Grade Intersection With Stop ControlFigure 910-18a

Sight distance Sight distance

Sight lineSight line

V

V

The tg values listed in Table 2 require thefollowing adjustments:

Crossing maneuvers:

All vehicles subtract 1.0 s

Multilane roadways:

Left-turns, for each lane in excess of one tobe crossed and for medians wider than 1.2 m:

Passenger cars add 0.5 sAll trucks and buses add 0.7 s

Crossing maneuvers, for each lane in excessof two to be crossed and for medians widerthan 1.2 m:

Passenger cars add 0.5 sAll trucks and buses add 0.7 s

Note: Where medians are wide enough tostore the design vehicle, determine the sightdistance as two maneuvers.

Crossroad grade greater than 3%:

All movements upgrade, for each percentthat exceeds 3%:

All vehicles add 0.2 s

SD = 0.45Vtg

Where:

SD = Sight Distance (m)

V = Design speed of the throughroadway (mph)

tg = Time gap for the minor roadwaytraffic to enter or cross the throughroadway (s)

Intersection Sight Distance EquationTable 1

Time Gap (tg)Design Vehicle in seconds

Passenger car (P) 9.5

Single unit trucks andbuses (SU & BUS) 11.5

Combination trucks(WB-12, WB-15, & WB-20) 13.5

Note: Values are for a stopped vehicle to turn leftor right onto a two-lane two-way roadwaywith no median and grades 3% or less.Includes 2 sec for perception/reaction time.

Intersection Sight DistanceGap Times (tg)

Table 2

Design Manual Intersections At GradeMay 2001 Metric Version Page 910-37

Sight Distance at IntersectionsFigure 910-18b

For bridge pier or bridge rail:

Where:

S = Available sight distance (m)

n = Offset from sight obstruction to edge oflane (m)

X = Distance from center line of lane to sightobstruction (m)

Sxn

=( )−

7 85 4

..

For crest vertical curve over a curb where S<L:

Where:

S = Available sight distance (m)

H1 = Eye height (1070 mm)

H2 = Object height (1300 mm)

HC = Curb height (mm)

L = Vertical curve length (m)

A = Algebraic difference in grades (%)

S0.1L 2 H HC 2 H HC

A

1 2

2

=−( ) + −( )[ ]

LAS

0.1 2 H HC 2 H HC

2

1 2

2=−( ) + −( )[ ]

Intersections At Grade Design ManualPage 910-38 Metric Version May 2001

Interchange Ramp DetailsFigure 910-19

Notes:

(1) 3.6 m through-lanes and 3.9 m left-turn lane desirable.

(2) For right-turn corner design see Figure 910-8.

(3) Intersections may be designed individually.

(4) Use templates for the WB-67 design vehicle.

(5) See Figure 910-11a, Table 1 for taper rates.

Commercial Approach — Single Approach Design Template DFigure 920-5

Design Manual Road ApproachesApril 1998 Metric Version Page 920-7

Road Approach Sight DistanceFigure 920-6

Road Approaches Design ManualPage 920-8 Metric Version May 2001

*Not to exceed 5.4 m from the edge of traveled way.

Posted SpeedLimit (mph) 25 30 35 40 50 60 70

Category IRoad Approach 45 55 70 85 115 155 190

Category IIRoad Approach 45 60 80 100 145 195 260

These distances require an approaching vehicle to reduce speed or stop to prevent a collision.

Design Category III road approach sight distance as an intersection (see Chapter 910).

For road approaches where left turns are not allowed, a sight triangle need only be provided to the left,as shown.

For road approaches where left turns are allowed, provide a sight triangle to the right in addition to theone to the left. The sight distance to the right is measured along the center line of the roadway.

For additional information on calculating the sight triangle, see Chapter 910.

Road Approach Spacing and Corner ClearanceFigure 920-7

Design Manual Road ApproachesMay 2001 Metric Version Page 920-9

Highway AccessManagement Class 1 2 3 4 5

S 402.4 m 201.2 m 100.6 m 76.2 m 38.1 m

Road Approach Spacing and Corner Clearance

Note:

For Road Approach Spacing, S is the distance between closest edge of the traveled way of the two roadapproaches, measured along the edge of the traveled way of the highway.

For corner clearance, S is measured from the closest edge of the traveled way of the crossroad to theclosest edge of the traveled way of the road approach, measured along the edge of the traveled way ofthe highway.

Selection of the final design must be based ona study of projected traffic volumes, site condi-tions, geometric controls, criteria for intersectinglegs and turning roadways, driver expectancy,consistent ramp patterns, continuity, and cost.

The patterns most frequently used for interchangedesign are those commonly described as direc-tional, semidirectional, cloverleaf, partialcloverleaf, diamond, and single point (urban)interchange. (See Figure 940-4.)

(a) Directional A directional interchangeis the most effective design for connection ofintersecting freeways. The directional patternhas the advantage of reduced travel distance,increased speed of operation, and higher capacity.These designs eliminate weaving and have afurther advantage over cloverleaf designs inavoiding the loss of sense of direction driversexperience in traveling a loop. This type ofinterchange is costly to construct, commonlyusing a four-level structure.

(b) Semidirectional A semidirectionalinterchange has ramps that loop around theintersection of the highways. This requiresmultiple single-level structures and more areathan the directional interchange.

(c) Cloverleaf The full cloverleaf interchangehas four loop ramps that eliminate all the left-turnconflicts. Outer ramps provide for the right turns.A full cloverleaf is the minimum type interchangethat will suffice for a freeway-to-freeway inter-change. Cloverleaf designs often incorporate aC-D road to minimize signing difficulties andto remove weaving conflicts from the mainroadway.

The principal advantage of this design is theelimination of all left-turn conflicts with onesingle-level structure. Because all movementsare merging movements, it is adaptable to anygrade line arrangement.

The cloverleaf has some major disadvantages.The left-turn movement has a circuitous routeon the loop ramp, the speeds are low on the loopramp, and there are weaving conflicts betweenthe loop ramps. The cloverleaf also requires alarge area. The weaving and the radius of the

loop ramps are a capacity constraint on theleft-turn movements.

(d) Partial Cloverleaf (PARCLO) A partialcloverleaf has loop ramps in one, two, or threequadrants that are used to eliminate the majorleft-turn conflicts. These loops may also serveright turns for interchanges that have one or twoquadrants that must remain undeveloped. Outerramps are provided for the remaining turns.Design the grades to provide sight distancebetween vehicles approaching these ramps.

(e) Diamond A diamond interchange has fourramps that are essentially parallel to the majorarterial. Each ramp provides for one right and oneleft-turn movement. Because left-turns are madeat grade across conflicting traffic on the cross-road, intersection sight distance is a primaryconsideration.

The diamond design is the most generallyapplicable and serviceable interchange config-uration and usually requires less space than anyother type. Consider this design first when asemidirectional interchange is required unlessanother design is clearly dictated by traffic,topography, or special conditions.

(f) Single Point (Urban) A single point urbaninterchange is a modified diamond with all of itsramp terminals on the crossroad combined intoone signalized at-grade intersection. This singleintersection accommodates all interchange andthrough movements.

A single point urban interchange can improve thetraffic operation on the crossroad with less rightof way than a standard diamond interchange;however, a larger structure is required.

(3) SpacingTo avoid excessive interruption of main linetraffic, consider each proposed facility in con-junction with adjacent interchanges, intersections,and other points of access along the route as awhole.

The minimum spacing between adjacent inter-changes is 1.5 km in urban areas and 3.0 kmin rural areas. In urban areas, spacing less than1.5 km may be used with C-D roads or gradeseparated (braided) ramps. Generally, the average

Design Manual Traffic InterchangesJune 1999 Metric Version Page 940-3

interchange spacing is not less than 3.0 km inurban areas and not less than 6.0 km in suburbanareas. Interchange spacing is measured along thefreeway center line between the center lines ofthe crossroads.

The spacing between interchanges may also bedependent on the spacing between ramps. Theminimum spacing between the noses of adjacentramps is given on Figure 940-5.

Consider either frontage roads or C-D roadswhen it is necessary to facilitate the operation ofnear-capacity volumes between closely spacedinterchanges or ramp terminals. C-D roads maybe required where cloverleaf loop ramps areinvolved or where a series of interchange rampsthat require overlapping of the speed changelanes. Base the distance between successive rampterminals on capacity requirements and checkthe intervening sections by weaving analysisto determine whether adequate capacity, sightdistance, and effective signing can be ensuredwithout the use of auxiliary lanes or C-D roads.

(4) Route ContinuityRoute continuity refers to the providing of adirectional path along the length of a routedesignated by state route number. Provide thedriver of a through route a path on which lanechanges are minimized and other trafficoperations occur to the right.

In maintaining route continuity, interchangeconfiguration may not always favor the heavytraffic movement, but rather the through route.In this case, design the heavy traffic movementswith multilane ramps, flat curves, and reasonablydirect alignment.

(5) DrainageAvoid interchanges located in proximity tonatural drainage courses. These locations oftenresult in complex and unnecessarily costlyhydraulic structures.

The open areas within an interchange can be usedfor storm water detention facilities when thesefacilities are required.

(6) Uniformity of Exit PatternWhile interchanges are of necessity customdesigned to fit specific conditions, it is desirable

that the pattern of exits along a freeway havesome degree of uniformity. From the standpointof driver expectancy, it is desirable that eachinterchange have only one point of exit, locatedin advance of the crossroad.

940.05 Ramps(1) Ramp Design SpeedThe design speed for a ramp is based on thedesign speed for the freeway main line.

The guidelines shown in Figure 940-1 are for theramp at the interchange connection. Vary theramp design speed to provide a smooth speedtransition from the interchange connection to thecrossroad speed or the stop at the intersection.Existing ramps meet design speed requirementsif acceleration or deceleration requirements aremet (Figure 940-8 or 940-10) and superelevationmeets or will be corrected to meet the require-ments in Chapter 640. Variations in curvaturemay prevent design of an interchange ramp fora constant design speed, but under no conditionsmay design speed be reduced below 35 mph forfreeway to freeway ramps and 25 mph for otherramps. For loop ramps the design speed may bereduced to 25 mph; however, it is desirable thatthe design speed be as high as practical. ForC-D roads the design speed is 10 mph belowthe main line design speed. Use the allowedskew at the crossroad intersection to minimizeramp curvature.

Main Line DesignSpeed mph 40 50 60 70 80

Ramp DesignSpeed (mph) 35 45 50 60 70

Ramp Design SpeedFigure 940-1

(2) Sight DistanceDesign ramps in accordance with provisions inChapter 650 for stopping sight distances.

(3) GradeThe maximum grade for ramps for various designspeeds is given in Figure 940-2.

Traffic Interchanges Design ManualPage 940-4 Metric Version May 2001

1010 Auxiliary Lanes

1010.01 General1010.02 References1010.03 Definitions1010.04 Climbing Lanes1010.05 Passing Lanes1010.06 Slow Moving Vehicle Turnouts1010.07 Shoulder Driving for Slow Vehicles1010.08 Emergency Escape Ramps1010.09 Chain-Up Areas1010.10 Documentation

1010.01 GeneralAuxiliary lanes are used to comply with capacityrequirements; to maintain lane balance; toaccommodate speedx change, weaving, andmaneuvering for entering and exiting traffic;or to encourage carpools, vanpools, and the useof transit.

See the Traffic Manual and the MUTCD forsigning of auxiliary lanes.

Although slow vehicle turnouts, shoulder drivingfor slow vehicles, and chain-up areas are notauxiliary lanes they are covered in this chapterbecause they perform a similar function.

See the following chapters for additionalinformation:

Chapter Subject

910 Turn lanes910 Speed change lanes at intersections940 Speed change lanes at interchanges940 Collector distributor roads940 Weaving lanes1050 High occupancy vehicle lanes

1010.02 ReferencesRevised Code of Washington (RCW) 46.61,Rules of the Road.

Manual on Uniform Traffic Control Devicesfor Streets and Highways (MUTCD), USDOT,FHWA; including the Washington State Modifi-cations to the MUTCD, M 24-01. WSDOT

Traffic Manual, M 51-02, WSDOT.

A Policy on Geometric Design of Highways andStreets (Green Book), AASHTO, 1994

Emergency Escape Ramps for Runaway HeavyVehicles, FHWA-T5-79-201, March 1978

Highway Capacity Manual (Special Report 209),Transportation Research Board

NCHRP Synthesis 178, Truck Escape Ramps,Transportation Research Board

1010.03 Definitionsauxiliary lane The portion of the roadwayadjoining the through lanes for parking, speedchange, turning, storage for turning, weaving,truck climbing, passing, and other purposessupplementary to through-traffic movement.

climbing lane An auxiliary lane used for thediversion of slow traffic from the through lane.

emergency escape ramp A roadway leavingthe main roadway designed for the purpose ofslowing and stopping out-of-control vehiclesaway from the main traffic stream.

lane A strip of roadway used for a single lineof vehicles.

lateral clearance The distance from the edgeof traveled way to a roadside object.

posted speed The maximum legal speed asposted on a section of highway using regulatorysigns.

passing lane An auxiliary lane on a two-lanehighway used to provide the desired frequencyof safe passing zones.

roadway The portion of a highway, includingshoulders, for vehicular use. A divided highwayhas two or more roadways.

shoulder The portion of the roadwaycontiguous with the traveled way, primarily foraccommodation of stopped vehicles, emergencyuse, lateral support of the traveled way, and useby pedestrians and bicycles.

Design Manual Auxiliary LanesNovember 1999 Metric Version Page 1010-1

slow moving vehicle turnouts A widenedshoulder area to provide room for a slow movingvehicle to pull safely out of the through traffic,allow vehicles following to pass, and return tothe through lane.

traveled way The portion of the roadwayintended for the movement of vehicles, exclusiveof shoulders and lanes for parking, turning, andstorage for turning.

Warrant A minimum condition for which anaction is authorized. Meeting a warrant does notattest to the existence of an unsafe or undersirablecondition. Further justification is required.

1010.04 Climbing Lanes(1) GeneralNormally, climbing lanes are associated withtruck traffic, but they may also be considered inrecreational or other areas that are subject to slowmoving traffic. Climbing lanes are designedindependently for each direction of travel.

Generally, climbing lanes are provided when therequirements of two warrants - speed reductionand level of service - are exceeded. The require-ments of either warrant may be waived if, forexample, slow moving traffic is demonstrablycausing a high accident rate or congestion thatcould be corrected by the addition of a climbinglane. However, under most conditions climbinglanes are built when the requirements of bothwarrants are satisfied.

(2) Warrant No. 1 — Speed ReductionFigure 1010-2a shows how the percent and lengthof grade affect vehicle speeds. The data is basedon a typical heavy truck.

The maximum allowable entrance speed, asreflected on the graphs, is 55 mph. Note that thisis the maximum value to be used regardless of theposted speed of the highway. When the postedspeed is above 55 mph, use 55 mph in place ofthe posted speed. Examine the profile at least0.4 km preceding the grade to obtain a reasonableapproach speed.

If a vertical curve makes up part of the lengthof grade, approximate the equivalent uniformgrade length.

Whenever the gradient causes a 15 mph speedreduction below the posted speed limit for typicalheavy truck for either two-lane or multilanehighways, the speed reduction warrant is satisfied(see Figure 1010-2b for an example).

(3) Warrant No. 2 — Level of Service(LOS)The level of service warrant for two-lanehighways is fulfilled when the up-grade trafficvolume exceeds 200 VPH and the up-grade truckvolume exceeds 20 VPH. On multilane highways,use Figure 1010-3.

(4) DesignWhen a climbing lane is justified, design it inaccordance with Figure 1010-4. Provide signingand delineation to identify the presence of theauxiliary lane. Begin climbing lanes at the pointwhere the speed reduction warrant is met andend them where the warrant ends for multilaneand 90 m beyond for 2-lane highways. Considerextending the auxiliary lane over the crest toimprove vehicle acceleration and the sightdistance.

Design climbing lane width equal to that of theadjoining through lane and at the same crossslope as the adjoining lanes. When ever possible,maintain the shoulders at standard width for theclass of highway. However, on two-way two-lanehighways, the shoulder may be reduced to 1.2 mwith justification.

1010.05 Passing Lanes(1) GeneralPassing lanes are desirable where a sufficientnumber and length of safe passing zones donot exist and the speed reduction warrant fora climbing lane is not satisfied. Figure 1010-5may be used to determine if a passing lane isrecommended.

(2) DesignWhen a passing lane is justified, design it inaccordance with Figure 1010-6. Make the lanelong enough to permit several vehicles to pass.Passing lanes longer than 3 km can cause thedriver to lose the sense that the highway isbasically a two-lane facility.

Auxiliary Lanes Design ManualPage 1010-2 Metric Version May 2001

Passing lanes are preferably four-lane sections.

A three-lane section may be used, however.Alternate the direction of the passing lane atshort intervals to ensure passing opportunitiesfor both directions and to discourage illegalactions of frustrated drivers.

Make the passing lane width equal to theadjoining through lane and at the same crossslope. Full-width shoulders for the highwayclass are preferred; however, with justification,the shoulders may be reduced to 1.2 m. Provideadequate signing and delineation to identify thepresence of an auxiliary lane.

1010.06 Slow Moving VehicleTurnouts(1) GeneralOn a two-lane highway where passing is unsafe,a slow moving vehicle is required, by RCW46.61.427, to turn off the through lane wherever asafe turnout exists, in order to permit the follow-ing vehicles to proceed. A slow moving vehicleis one that is traveling at a speed less than thenormal flow of traffic, behind which five ormore vehicles are formed in a line.

A slow moving vehicle turnout is not an auxiliarylane. Its purpose is to provide sufficient roomfor a slow moving vehicle to safely pull out ofthrough traffic and stop if necessary, allowvehicles following to pass, then return to thethrough lane. Generally, a slow moving vehicleturnout is provided on existing roadways wherepassing opportunities are limited, where slowmoving vehicles such as trucks and recreationalvehicles are predominant, and where the cost toprovide a full auxiliary lane would be prohibitive.

(2) DesignBase the design of a slow moving vehicle turnoutprimarily on sound engineering judgment andFigure 1010-7. Design may vary from onelocation to another. A minimum length of 30 mprovides adequate storage, since additionalstorage is provided within the tapers and shoul-ders. The maximum length is 0.5 km includingtapers. Surface turnouts with a stable unyieldingmaterial such as BST or ACP with adequatestructural strength to support the heavier traffic.

Locate slow vehicle turnouts where at leastDesign Stopping Sight Distance (Chapter 650)is available, decision sight distance is preferred,so that vehicles can safely reenter the throughtraffic. Sign slow moving vehicle turnouts toidentify their presence.

When a slow moving vehicle turnout is to bebuilt, document the location and why it wasselected.

1010.07 Shoulder Driving for SlowVehicles(1) GeneralFor projects where climbing or passing lanesare justified, but are not within the scope of theproject, or where meeting the warrants for theselanes are borderline, the use of a shoulder drivingsection is an alternative.

Review the following when considering ashoulder driving section:

• Horizontal and vertical alignment

• Character of traffic

• Presence of bicycles

• Clear zone (Chapter 700)

(2) DesignWhen designing a shoulder for shoulder driving,use a minimum length of 180 m. The minimumshoulder width is 2.4 m with 3.0 m preferred.When barrier is present, the minimum width is3.0 m with 3.6 m preferred. Adequate structuralstrength for the anticipated traffic is necessaryand may require reconstruction. Select locationswhere the side slope meets the requirements ofChapter 640 for new construction and Chapter430 for existing roadways. When a transition isrequired at the end of a shoulder driving section,use a 50:1 taper.

Signing for shoulder driving is required. Installguideposts when shoulder driving is to bepermitted at night.

Document the need for shoulder driving and whya lane is not being built.

Design Manual Auxiliary LanesNovember 1999 Metric Version Page 1010-3

1010.08 Emergency EscapeRamps(1) GeneralConsider an emergency escape ramp wheneverlong steep down grades are encountered. In thissituation the possibility exists of a truck losing itsbrakes and going out of control at a high speed.Consult local maintenance personnel and checktraffic accident records to determine if an escaperamp is justified.

(2) Design(a) Type. Escape ramps are one of thefollowing types:

• Gravity escape ramps are ascending graderamps paralleling the traveled way. They arecommonly built on old roadways. Their longlength and steep grade can present the driverwith control problems, not only in stopping,but with rollback after stopping. Gravityescape ramps are the least desirable design.

• Sand pile escape ramps are piles of loose,dry sand dumped at the ramp site, usually notmore than 120 m in length. The decelerationis usually high and the sand can be affectedby weather conditions; therefore, they are lessdesirable than arrester beds. However, wherespace is limited they may be suitable.

• Arrester beds are parallel ramps filled witha smooth, coarse, free-draining gravel. Theystop the out-of-control vehicle by increasingthe rolling resistance. Arrester beds arecommonly built on an up grade to add thebenefits of gravity to the rolling resistance.However, successful arrester beds have beenbuilt on a level or descending grade.

(b) Location. The location of an escape rampwill vary depending on terrain, length of grade,and roadway geometrics. The best locationsinclude in advance of a critical curve, near thebottom of grade, or before a stop. It is desirablethat the ramp leave the roadway on a tangent atleast 5 km from the beginning of the down-grade.

(c) Length. Lengths will vary dependingon speed, grade, and type of design used. Theminimum length is 60 m. Calculate the stoppinglength using the following equation:

L =

Where:L = stopping distance (m)V = entering speed (mph)R = rolling resistance (see Figure 1010-1)G = grade of the escape ramp (%)

Speeds of out-of control trucks rarely exceed90 mph; therefore, an entering speed of 90 mphis preferred. Other entry speeds may be usedwhen justification and the method used todetermine the speed is documented.

Material R

Roadway 1

Loose crushed aggregate 5

Loose noncrushed gravel 10

Sand 15

Pea gravel 25

Rolling Resistance (R)Figure 1010-1

(d) Width. The width of each escape ramp willvary depending on the needs of the individualsituation. It is desirable for the ramp to be wideenough to accommodate more than one vehicle.The desirable width of an escape ramp to accom-modate two out-of-control vehicles is 12 m andthe minimum width is 8 m.

(e) The following items are additional consider-ations in the design of emergency escape ramps:

• If possible, at or near the summit, providea pull-off brake-check area. Also, includeinformative signing about the upcomingescape ramp in this area.

• A free draining, smooth, noncrushed gravelis preferred for an arrester bed. To assist insmooth deceleration of the vehicle, taper thedepth of the bed from 75 mm at the entry toa full depth of 600 to 750 mm in not lessthan 30 m.

• Mark and sign in advance of the ramp.Discourage normal traffic from using orparking in the ramp. Sign escape ramps inaccordance with the guidance contained inthe MUTCD for runaway truck ramps.

V2

0.98(R±G)

Auxiliary Lanes Design ManualPage 1010-4 Metric Version November 1999

• Provide drainage adequate to prevent the bedfrom freezing or compacting.

• Consider including an impact attenuator atthe end of the ramp if space is limited.

• A surfaced service road adjacent to thearrester bed is needed for wreckers andmaintenance vehicles to remove vehiclesand make repairs to the arrester bed.Anchors are desirable at 90 m intervals tosecure the wrecker when removing vehiclesfrom the bed.

A typical example of an arrester bed is shown inFigure 1010-8.

Include justification, all calculations, and anyother design considerations in the documentationof an emergency escape ramp documentation.

1010.09 Chain-Up AreaProvide chain-up areas to allow chains to be puton vehicles out of the through lanes at locationswhere traffic enters chain enforcement areas.Provide chain-off areas to remove chains outof the through lanes for traffic leaving chainenforcement areas.

Chain-up or chain-off areas are widened shoul-ders, designed as shown in Figure 1010-9. Locatechain-up and chain-off areas where the grade is6% or less and preferably on a tangent section.

Consider illumination for chain-up and chain-offareas on multilane highways. When decidingwhether or not to install illumination, considertraffic volumes during the hours of darkness andthe availability of power.

1010.10 DocumentationThe following documents are to be preserved inthe project file. See Chapter 330.

� Documentation that climbing lane warrant1 has been met

� Documentation that climbing lane warrant2 has been met

� Justification for waiving climbing lanewarrant 1 or 2

� Justification for passing lanes

� Slow moving vehicle turnoutdocumentation

� Emergency escape ramp documentation

Design Manual Auxiliary LanesNovember 1999 Metric Version Page 1010-5

Performance For Heavy TruckFigure 1010-2a

Auxiliary Lanes Design ManualPage 1010-6 Metric Version November 1999

Given: A 2-lane highway meeting the level of service warrant, with the above profile, and a 55 mphposted speed.

Determine: Is the climbing lane warranted and, if so, how long?

Solution:

1. Follow the 4% grade deceleration curve from a speed of 55 mph to a speed of 40 mph at 500 m. Thespeed reduction warrant is met and a climbing lane is needed.

2. Continue on the 4% grade deceleration curve to 1200 m. Note that the speed at the end of the 4%grade is 25 mph.

3. Follow the 1% grade acceleration curve from a speed of 25 mph for 300 m. Note that the speed at theend of the 1% grade is 34 mph.

4. Follow the -2% grade acceleration curve from a speed of 34 mph to a speed of 40 mph, ending thespeed reduction warrant. Note the distance required is 100 m.

5. The total auxiliary lane length is (1200-500)+300+100+90=1190 m. 90 m is added to the speedreduction warrant for a 2-lane highway, see the text and Figure 1010-4.

Speed Reduction ExampleFigure 1010-2b

Design Manual Auxiliary LanesNovember 1999 Metric Version Page 1010-7

Level of Service — MultilaneFigure 1010-3

Auxiliary Lanes Design ManualPage 1010-8 Metric Version May 2001

Design Manual Bicycle FacilitiesMay 2001 Metric Version Page 1020-1

1020 Bicycle Facilities

Uniform Traffic Control Devices including theWashington State Modifications to the MUTCD,M 24-01, WSDOT

Washington Administrative Code (WAC)468-95-035, Pavement Edge and Raised Pave-ment Markers Supplementing Other Markings

Revised Code of Washington (RCW) 46.61,Rules of the Road

RCW 46.61.710, Mopeds, electric-assistedbicycles—General requirements and operation

Standard Plans for Road, Bridge, and MunicipalConstruction (Standard Plans), M 21-01,WSDOT

State Highway System Plan, WSDOT

1020.03 Definitionsbicycle route A system of bikeways,designated by the jurisdiction(s) having theauthority, featuring appropriate directionaland informational route markers. A series ofbikeways may be combined to establish acontinuous route and may consist of any orall types of bicycle facilities.

bike lane A portion of a highway or streetidentified by signs and/or pavement markingsreserved for bicycle use.

bikeway Any trail, path, part of a highway orshoulder, or any other traveled way specificallysigned and/or marked for bicycle travel.

Category A bicyclist Advanced or experiencedriders who are generally using their bicycles asthey would a motor vehicle. They want directaccess to destinations with a minimum of delayand are comfortable riding with motor vehicletraffic. When touring, their vehicles are com-monly heavily loaded with a tandem rider(s),children, or camping gear. They need sufficientoperating space on the traveled way or shoulderto eliminate the need for them or passing vehiclesto shift position.

1020.01 General1020.02 References1020.03 Definitions1020.04 Planning1020.05 Design1020.06 Documentation

1020.01 GeneralThe Washington State Department of Transpor-tation (WSDOT) encourages multimodal use ofits transportation facilities. Bicycle facilities orimprovements for bicycle transportation areincluded in the project development and highwayprogramming processes where bicycle use islikely and can be accommodated safely.

This chapter is to serve as a guide for selectingand designing the most useful and cost-effectivebicycle facility possible and for how to includethe region’s Bicycle Coordinator in the designprocess. These guidelines apply to normalsituations encountered during project develop-ment. Unique design problems are resolved ona project-by-project basis using guidance fromthe region’s Bicycle Coordinator.

State law (46.61.710 RCW) prohibits the opera-tion of mopeds on facilities specifically designedfor bicyclists, pedestrians, and equestrians.Mopeds are not considered in the design processfor the purposes of this chapter.

In general, do not mix equestrian and bicycletraffic on a shared use path. Consider designinga bridle trail that is separate from the shared usepath in common equestrian corridors.

1020.02 ReferencesGuide for the Development of Bicycle Facilities,1999, AASHTO

A Policy on Geometric Design of Highways andStreets (Green Book), 1994, AASHTO

Manual on Uniform Traffic Control Devices(MUTCD), Federal Highway Administration(FHWA), National Advisory Committee on

Bicycle Facilities Design ManualPage 1020-2 Metric Version May 2001

Category B bicyclist Basic or less confidentadult bicyclists who might be using their bicyclesfor transportation purposes. They prefer to avoidroads with fast and busy motor vehicle trafficunless there is ample roadway width. Basicbicyclists are comfortable riding on neighborhoodstreets and shared use paths; however, on busierstreets, they prefer designated facilities such asbike lanes or wide shoulder lanes.

Category C bicyclist Children, riding aloneor with their parents, who need access to keydestinations in the community such as schools,friends, recreational facilities, and conveniencestores. Residential streets with low motor vehiclespeeds (linked with shared use paths and busierstreets with well-defined pavement markingbetween bicycles and motor vehicles) can accom-modate children without encouraging them toride in the traveled lane of major arterials.

rural bicycle touring routes State highways orsections of state highways that are used or havea high potential for use by Category A bicyclistsriding long distance on single or multiday trips.

shared roadway A roadway that is open toboth bicycle and motor vehicle travel. Sharedroadways do not have dedicated facilities forbicycle travel.

signed shared roadway (designated as a bikeroute) A shared roadway that has been desig-nated by signing as a preferred route for bicycleuse. Appropriate bike route signs are installedto assure bicyclists that improvements such aswidening shoulders have been made to improvesafety.

shared use path A facility on exclusive right ofway with minimal cross flow by motor vehicles.It is designed and built primarily for use bybicycles but is also used by pedestrians, joggers,skaters, wheelchair users (both nonmotorized andmotorized), and others.

1020.04 Planning(1) GeneralBikeway planning includes provisions andfacilities for safe and efficient bicycle travel.An effective multimodal transportation program

addresses the issue of upgrading highways toaccommodate shared use by bicyclists andmotorists.

Bicyclists of all skill levels will use well-designed facilities. Bicyclists will avoid a poorlydesigned facility.

To enhance bicycle travel, consider upgradingexisting roads that are used regularly byCategory A or B bicyclists. The upgradingincludes improving the width and quality of thesurface and maintaining the right-hand portionin a condition suitable for bicycle riding.

Consider bicycle facilities when designingconstruction projects and normal safety andoperational improvements. Shoulder wideningprojects along existing highways, might be anopportunity to encourage bicycle traffic andenhance bicycle safety. Correcting short areasof restricted width (such as bridges, cuts, or fills)to provide bikeways might not be cost effective.However, the presence of these short, restrictedareas does not diminish the importance ofwidening the adjoining shoulder sections.

Bikeway planning is an integral part of thefacility planning for other transportation modesand land use development. Use the locationcriteria that follow for long-term planning andproject development as applicable.

(2) ProgrammingThe State Highway System Plan identifies twoelements of bicycle project funding:

• Urban Bicycle Projects: Complete localbicycle networks by building short sectionsof appropriate bicycle facilities along oracross state highways.

• Rural Bicycle Touring Routes: Shoulderimprovements along sections of designatedstate routes.

Urban Bicycle Projects have been prioritized bythe region’s Planning Offices, the OSC BicycleProgram, and the department’s Bicycle AdvisoryCommittee and are listed in the State HighwaySystem Plan. Urban Bicycle Projects are selectedin each region, prioritized, and will competefor funding.

Design Manual Bicycle FacilitiesMay 2001 Metric Version Page 1020-3

Rural Bicycle Touring Routes (RBTR) program-ming priority areas are listed in the StateHighway System Plan. Each region’s PlanningOffice has a map with the priority areas marked.The purpose of the RBTR program is to addfunding to a project in an RBTR shoulder defi-ciency area. Designers are to consult the region’sPlanning Office to determine if their project iswithin an RBTR shoulder deficiency area. If theproject is within an RBTR shoulder deficiencyarea, the designer requests the region’s ProgramManagement to determine RBTR fundingavailability.

Consider spot bikeway improvements in othertypes of projects such as P1 paving and I2 safetyimprovement projects. Identify small improve-ments in the project definition phase. Consult theregion’s Bicycle Coordinator for recommenda-tions and the limits of the work. Funding fromother sources such as the Urban Bicycle andRural Bicycle programs might be available.

(3) Selection of the Type of FacilityIn selecting an appropriate facility, ensure thatthe proposed facility will not encourage orrequire bicyclists or motorists to operate in amanner that is inconsistent with the Rules of theRoad (RCW 46.61).

An important consideration is route continuity.Alternating bikeways from side to side along aroute is generally unacceptable. Designing a routethat requires bicyclists to cross the roadway couldresult in inappropriate maneuvers and/or encour-age Rules of the Road violations. In addition,wrong-way bicycle travel might occur beyondthe ends of shared use paths because of theinconvenience of having to cross the street.

Many factors are involved in determining whichtype of facility will benefit the greatest number ofbicyclists. Outlined below are the most commonapplications for each type.

Shared Use PathFigure 1020-1

(a) Shared Use Path. The most commonapplications for shared use paths (See Figure1020-1) are along rivers and streams, oceanbeachfronts, canals, utility rights of way, andabandoned railroad rights of way; within collegecampuses; and within and between parks. Theremight also be situations where such facilities canbe provided as part of planned developments.Another common application of shared use pathsis to close gaps in bicycle travel caused byconstruction of freeways, or the existence ofnatural barriers (rivers, mountains, and otherlarge geographic features).

Generally, shared use paths are used to servecorridors not served by streets and highways orwhere wide rights of way exist permitting suchfacilities to be constructed away from the influ-ence of parallel roadways. Shared use paths offeropportunities not provided by the road system.They can either provide a recreational opportu-nity or serve to minimize motor vehicleinterference by providing direct high-speedbicycle commute routes.

Bicycle Facilities Design ManualPage 1020-4 Metric Version May 2001

Bike LaneFigure 1020-2

(b) Bike Lane. Bike lanes are established alongstreets in corridors where there is or, in the future,might be significant bicycle demand. (See Figure1020-2.) Bike lanes delineate the rights of wayassigned to bicyclists and motorists and providefor movements that are more predictable by each.An important reason for establishing bike lanesis to better accommodate bicyclists throughcorridors where insufficient room exists forsafe bicycling on existing streets. This can beaccomplished by reducing the number of lanesor prohibiting parking in order to delineate bikelanes.

Where street improvements are not possible,improve the bicyclist’s environment by providingshoulder sweeping programs and special signalfacilities.

When considering the selection of appropriatestreets for bike lanes, refer to the location criteriadiscussed in 1020.04(4).

Do not designate sidewalks as bike lanes.

Shared RoadwayFigure 1020-3

(c) Shared Roadway. Most bicycle travel inWashington occurs on highways and streetswithout bikeway designations. (See Figure1020-3.) In most instances, entire street systemsare fully adequate for safe and efficient bicycletravel and signing and pavement markings forbicycle use are unnecessary.

The region’s Traffic are responsible for deter-mining sections of state highways where bicycletraffic is inappropriate. The State Traffic Engi-neer, after consultation with the Bicycle AdvisoryCommittee, prohibits bicycling on sections ofstate highways through the traffic regulationprocess. Also, see Chapter 1420 “Access ControlDesign Policy” .

Bicyclists traveling between cities, or onrecreational trips, may use many rural highways.In most cases, rural highways are not designatedas bike routes because of the limited use and thelack of continuity with other bike routes. How-ever, the development and maintenance of pavedshoulders, with or without a standard edge stripe,can significantly improve safety and conveniencefor bicyclists and motorists along such routes.

Design Manual Bicycle FacilitiesMay 2001 Metric Version Page 1020-5

Signed Shared Roadway(Designated Bike Route)

Figure 1020-4

(d) Signed Shared Roadway. Designate signedshared roadways as bike routes by posting bikeroute signs. (See Figure 1020-4.) These routesprovide continuity to other bicycle facilities anddesignate preferred routes through high bicycle-demand corridors. As with bike lanes,designating shared roadways as bike routes is anindication to bicyclists that there are particularadvantages to using these bike routes as com-pared with alternative routes. This means that theresponsible agencies have taken action to ensurethat these routes are suitable as bike routes andare maintained in a manner consistent with theneeds of bicyclists. Signing also alerts motorvehicle operators that bicycles are present.

Use the following criteria to aid in determiningwhether or not to designate and sign a bike route:

• The route offers a higher degree of servicethan alternative streets.

• It provides for through and direct travel inbicycle-demand corridors.

• It connects discontinuous segments ofbikeways.

• Traffic control devices have been adjusted toaccommodate bicyclists.

• Street parking is restricted for improvedsafety where lane width is critical.

• Surface hazards to bicyclists have beencorrected.

• Maintenance of the route is to a higherstandard than comparable streets, such asmore frequent street sweeping and repair.

In general, do not designate sidewalks asbikeways for the following reasons:

• Sidewalks tend to be used in both directions,despite any signing to the contrary.

• At approaches to intersections, parked carsmight impede sight distance of motorists andbicyclists. At driveways, property fences,shrubs, and other obstructions often impairsight distances.

• At intersections, motorists are not lookingfor bicyclists entering the crosswalk area,particularly when motorists are makinga turn.

• Sidewalks are typically designed forpedestrian speeds, and might not be safe forhigher-speed use. Conflicts between bicy-clists and pedestrians are common, as areconflicts with fixed objects such as parkingmeters, utility poles, signposts, bus shelters,benches, trees, hydrants, and mailboxes. Inaddition, bicyclists riding on the curb sideof sidewalks might accidentally drop offthe sidewalk into the path of motor vehicletraffic.

Only consider a sidewalk as a bike route underspecial circumstances, such as on long, narrowbridges. Even then, the preferred solution is towiden the roadway to provide space for bicy-clists. In residential areas, sidewalk riding iscommonly done by Category B and C bicyclistswho are not comfortable riding in the street.However, it is inappropriate to sign thesefacilities as bike routes.

(4) Location CriteriaFactors to consider in determining the locationof a bikeway are:

(a) Potential Use. Locate bikeways alongcorridors or a convenient road parallel to thecorridor to maximize use. However, to attractcommuting bicyclists, the roadway must offerthrough route conditions.

Bicycle Facilities Design ManualPage 1020-6 Metric Version May 2001

(b) Directness. Locate facilities along a directline and in such a way that they connect bicycletraffic generators for the convenience of theusers. Bicyclists are interested in the samedestinations as motorists.

(c) Access. When locating a shared use path,provide adequate access points. The moreaccess points, the more the facility will beused. Adequate access for emergency andservice vehicles is also necessary.

(d) Shared Use Path Widths. Figure 1020-13shows the widths and minimum horizontalclearances needed when a shared use path ison an alignment separate from a highway rightof way.

Figure 1020-14 shows shared use path widthwhen adjacent to a roadway and within its rightof way. See 1020.05(2)(e) to find if a barrierwill be needed.

(e) Available Roadway Width. For a bike laneor shared roadway (with or without signing), theoverall roadway width must meet or exceed thehighway minimum design criteria. See Chapter430 “Modified Design Level” and 440 “FullDesign Level” and Figures 1020-14 and 1020-15for further width information.

(f) On-Street Motor Vehicle Parking.Consider the density of on-street parking and thesafety implications, such as opening car doors. Ifpossible, select a route where on-street parking islight or where it can be prohibited.

(g) Delays. Bicyclists have a strong desire tomaintain momentum. If bicyclists are required tomake frequent stops, they might avoid the route.

(h) Traffic Volumes and Speeds. For anon-street bikeway, the volume and speed of autotraffic, along with the available width, are factorsin determining the best location. Commutingbicyclists generally ride on arterial streets tominimize delay and because they are normallythe only streets offering continuity for trips ofseveral miles. The FHWA has developed aspreadsheet to evaluate roadways for bicyclecompatibility. The Bicycle Compatibility Index(BCI) measures roadways based on traffic

volume, speed, lane width, and other factors.A copy of the BCI and supporting informationis found at http://www.hsrc.unc.edu/research/pedbike/bci/index.html

(i) Truck and Bus Traffic. High-speed truck,bus, and recreational vehicle traffic can causeproblems along a bikeway because of aerody-namic effects and vehicle widths. Evaluate theneed to widen shoulders or change the locationof the bicycle facility if it is on a roadway withthis type of traffic.

(j) Existing Physical Barriers. In some areasthere are physical barriers to bicycle travel causedby topographical features such as rivers, limitedaccess highways, or other impediments. In suchcases, developing a facility that allows a bikewayto cross an existing barrier can provide accessopportunities for bicyclists.

(k) Collision History. Check the collisionexperiences along a prospective bicycle routeto determine its relative safety compared to othercandidate routes. This involves analysis of thecollision types to determine which of them mightbe reduced. (See 1020.04(4)(p).) Consider boththe impacts caused by adding bicycle traffic andthe potential for introducing new accident prob-lems. The region’s Traffic Office is a goodresource when considering collision factors.

(l) Grades. Avoid steep grades on bikewayswhenever possible. Refer to 1020.05(2)(k) forspecific criteria.

(m) Pavement Surface Quality. Establish anon-street bikeway only where pavement can bebrought to a reasonable condition for safe bicycletravel. Dense graded asphalt concrete surfaces arepreferable to open-graded asphalt concrete,Portland cement concrete, and seal-coatedsurfaces.

(n) Maintenance. Ease of maintenance is animportant consideration in locating and develop-ing a bikeway. Consider the ease of access bymaintenance vehicles. Bicyclists will often shuna poorly maintained bikeway in favor of aparallel roadway. Consult with area maintenancepersonnel during the planning stage.

Design Manual Bicycle FacilitiesMay 2001 Metric Version Page 1020-7

(o) Environmental Compatibility. Considerscenic value, erosion and slope stability, andcompatibility with the surrounding terrain whendeveloping a bikeway. Provide landscaping tominimize adverse environmental effects.

(p) Use Conflicts. Different types of facilitiesproduce different types of conflicts. On-streetbikeways involve conflicts with motor vehicles.Shared use paths usually involve conflicts withother bicyclists, pedestrians, skaters, and runnerson the path, and with motor vehicles at streetintersections. Conflicts between bicyclists andmotorists can also occur at highway and drivewayintersections, tight corners, and narrow facilitieslike bridges and tunnels.

(q) Security. The potential for criminal actsagainst bicyclists and other users of bikewaysexists anywhere, especially along remotestretches. There also is the possibility of theft orvandalism at parking locations. Consult local lawenforcement agencies for guidance in makingthese areas safer. Also consider installation oftelephones in high risk areas.

(r) Cost/Funding. Location selection willnormally involve a cost comparison analysis ofalternatives. Funding availability will ofteneliminate some alternatives; however, it is moredesirable to delay constructing a bicycle facilitythan to construct an inadequate facility.

(s) Structures. Continuity can be providedto shared use path by using an overpass, under-pass, tunnel, bridge, or by placing the facility ona highway bridge to cross obstacles. See1020.05(2)(m) for design information.

Retrofitting bicycle facilities on existing bridgesinvolves a large number of variables; compro-mises in desirable design criteria are ofteninevitable. The planner, with the assistance ofthe region’s Bicycle Coordinator and the Bridgeand Structures Office, on a case-by-case basis,will determine the desirable design criteria.

Consider the following alternatives when placinga shared use path on an existing highway bridge:

• On one side of a bridge. Do this where: thebridge facility connects at both ends to thepath; there is sufficient width on that side of

the bridge or additional width can be gainedby remarking the pavement; and provisionshave been made to physically separate themotor vehicle traffic from the bicycle traffic.See Figure 1020-16.

• Provide bicycle lanes, shoulders, or widecurb lanes over a bridge. This is advisablewhere: bike lanes and shoulders connect oneither end of the structure, and when suffi-cient width exists or can be obtained bywidening or remarking the pavement. Usethis option only if the bike lane or wideoutside lane can be accessed without increas-ing the potential for wrong-way riding orinappropriate crossing movements.

(v) Lighting. Illumination of bicycle facilitiesmight be necessary to achieve minimum levels ofsafety, security, and visibility.

(w) Support Facilities. Where bicycles areused extensively for utility trips or commuting,consider placing adequate bicycle parking and/orstorage facilities at common destinations (such aspark and ride lots, transit terminals, schools, andshopping centers). Contact the region’s BicycleCoordinator for additional information.

1020.05 Design(1) Project RequirementsFor urban bicycle mobility improvement projects(Bike/Ped connectivity projects in the matrices,Chapter 325), apply the guidance in this chapterto the bikeway.

For highway design elements affected by theproject, apply the appropriate design level(Chapter 325) and as found in the applicableDesign Manual chapters.

For highway design elements not affected by theproject, no action is required.

(2) Design Criteria for SharedUse PathShared use paths are facilities for the primaryuse of bicyclists but are also used by pedestrians,joggers, skaters, and others.

Bicycle Facilities Design ManualPage 1020-8 Metric Version May 2001

(a) Widths. The geometric guidelines forshared use paths are shown in Figures 1020-13and 1020-14.

A path width of 2.4 m may be used when all thefollowing conditions apply:

• Bicycle traffic is expected to be low (lessthan 60 bicycles per day [bpd]).

• Pedestrian use is not expected to be morethan occasional.

• The horizontal and vertical alignment ad-equately provide safe and frequent passingopportunities.

• Normal maintenance activities can be per-formed without damaging the pavement edge.

The minimum paved width for a one-way shareduse path is 1.8 m. Use this minimum width onlyafter ensuring that one-way operation will beenforced and maintenance can be performed.

Where the shared use path is adjacent to canals,ditches, or fill slopes steeper than 1V:3H, con-sider a wider separation. A minimum 1.5 mseparation from edge of the pavement to the topof slope is desirable. A physical barrier, such asdense shrubbery, railing, or chain link fence isneeded at the top of a high embankment andwhere hazards exist at the bottom of anembankment.

(b) Clearance to Obstructions. The desirablehorizontal clearance from the edge of pavementto an obstruction (such as a bridge pier) is at least0.6 m. Where this cannot be obtained; installsigns and pavement markings to warn bicyclistsof the condition. See Figure 1020-5 for pavementmarking details.

The required minimum vertical clearance frombikeway pavement to overhead obstructions is2.4 m. However, a higher vertical clearancemight be needed for passage of maintenance andemergency vehicles.

L = WV, where V is bicycle approach speed (mph)

Obstruction MarkingFigure 1020-5

(c) Intersections with Highways. Collisions atintersections are the most common type of motorvehicle/bicycle collision. Shared use path androadway intersections must clearly define whohas the right of way and provide adequate sightdistance for both users. There are three types ofshared use path/roadway at-grade intersectioncrossings: midblock, adjacent path, and complex.Only at-grade midblock and adjacent crossingsare addressed here. Complex intersectionsinvolve special designs which must be consideredon a case-by-case basis.

W

L

200 mm solid

white marking

Pier, abutment, grate,

or other obstruction

Roadway

Direction o

f tr

avel

Design Manual Bicycle FacilitiesMay 2001 Metric Version Page 1020-9

At-grade crossings at existing intersections areusually placed with existing pedestrian crossingswhere motorists can be expected to stop. Ifalternate intersection locations for a shared usepath are available, select the one with the greatestsight distance.

When possible, place a crossing away from anintersection in order to eliminate conflicts.

Midblock crossings are the least complex of theother types of crossings. Locate midblock pathcrossings far enough away from intersections sothat there is no conflict between the path crossingand the intersection motor vehicle traffic activi-ties. A 90-degree intersection crossing ispreferable (Figure 1020-6). A 75-degree angle isacceptable. A 45-degree angle is the minimumacceptable to minimize right of way require-ments. A diagonal midblock crossing can bealtered as shown in Figure 1020-7.

Midblock Type Shared Use Path CrossingFigure 1020-6

Ro

adw

ay

Varies - see MUTCD Section 9B.15

Sh

are

d U

se

Path

W11-1

W2-1

XIN

G

15 m

1.2 m

1.2 m

1.5 m

XING

HWY

30 m 2.4 m 10 m 2.4 m

R5-3

R1-1

D11-1

/M7-5

R5-3R1-1

Sh

are

d U

se

Path

STOPSTOP

NO

MOTOR

VEHICLES

NO

MOTOR

VEHICLES

BIK

E R

OU

TE

Bicycle Facilities Design ManualPage 1020-10 Metric Version May 2001

There are other considerations when designingmidblock crossings, including right of wayassignment, traffic control devices, sight dis-tances for both bicyclists and motor vehicleoperators, refuge island use, access control,and pavement markings.

Adjacent path crossings occur where a pathcrosses an existing intersection of two roadways,a T intersection (including driveways), or a four-way intersection as shown in Figure 1020-8. It ispreferable to integrate this type of crossing closeto an intersection so that motorists and path users

recognize each other as intersecting traffic. Thepath user faces potential conflicts with motorvehicles turning left (A) and right (B) from theparallel roadway, and on the crossed roadway(C, D, E).

Complex intersection crossings are all other typesof path/roadway or driveway junctions. Theseinclude a variety of configurations where the pathcrosses directly through an existing intersectionof two or more roadways and where there can beany number of motor vehicle turning movements.

Note: The path and highway signing and markings are the same as in Figure 1020-6

Typical Redesign of a Diagonal Midblock CrossingFigure 1020-7

W1-3(R)

W1-3(L)

Path

Path

Intersecting Roadway

Design Manual Bicycle FacilitiesMay 2001 Metric Version Page 1020-11

Improvements to complex crossings must beconsidered on a case-by-case basis. Suggestedimprovements include: move the crossing, installa signal, change signization timing, or provide arefuge island and make a two-step crossing forpath users.

The major road might be either the parallel or thecrossed roadway. Important elements that greatlyaffect the design of these crossings are: right ofway assignment, traffic control devices, andseparation distance between path and roadway.

Other roadway/path design considerations:

• Traffic signals/stop signs. Determine theneed for traffic control devices at all path/roadway intersections by using MUTCD

Note: Signing will be the same as shown in Figure 1020-6.

Adjacent Shared Use Path IntersectionFigure 1020-8

warrants and engineering judgment. Bicyclesare considered vehicles in Washington Stateand bicycle path traffic can be classified asvehicular traffic for MUTCD warrants.Ensure that traffic signal timing is set forbicycle speeds.

• Manually operated signal actuationmechanisms. Locate the bicyclist’s signalbutton where it is easily accessible to bicy-clists and 1.2 m above the ground and place adetector loop in the path pavement.

• Signing. Place path stop signs as close tothe intended stopping point as possible. Four-way stops at shared use path and roadwayintersections are not advisable due to confu-

Parallel Roadway

Path

A

B

C D

E

Intersecting Roadway

Bicycle Facilities Design ManualPage 1020-12 Metric Version May 2001

sion about or disregard for right of way laws.Yield signs for path traffic are acceptable atsome locations, such as low-volume, low-speed neighborhood streets. Sign type, size,and location must be in accordance with theMUTCD. Do not place the shared use pathsigns where they will confuse motorists orplace roadway signs where they will confusebicyclists.

• Approach treatments. Design shared usepath and roadway intersections with flatgrades and adequate sight distances. Evaluatestopping sight distance at the intersection.Provide adequate advance warning signsand pavement makings (see MUTCD andWashington State Modifications to theMUTCD) that alert and direct bicycliststo stop before reaching the intersection,especially on downgrades. Provide unpavedshared use paths with paved aprons extendinga minimum of 3.0 m from the paved roadsurfaces. Speed bumps or other similarsurface obstructions intended to causebicyclists to slow down are not appropriate.

• Transition zones. Integrate the shared usepath into the roadway where the path termi-nates. Design these terminals to transitionthe bicycle traffic into a safe merging ordiverging condition. Appropriate signing isnecessary to warn and direct both bicyclistand motorist at the transition areas.

• Ramp widths. Design ramps for curb cutswith the same width as the shared use path.Curb cuts and ramps are to provide a smoothtransition between the shared use path and theroadway. Consider a 1.5 m radius or flare tofacilitate right turns for bicycles. This sameconsideration applies to intersections of twoshared use paths.

• Refuge islands. Consider refuge islandswhen one or more of the following applies:high motor vehicle traffic volume and speeds;wide roadways; crossing will be used byelderly, children, disabled, or other slowmoving users. See Figure 1020-17 for details.

(d) At-Grade Railroad Crossings. Whenevera bikeway crosses railroad tracks, continue thecrossing at least as wide as the approach bikeway.Wherever possible, design the crossing at rightangles to the rails. See Figure 1020-18.

For on-street bikeways, where a skew is unavoid-able, widen the shoulder (or bike lane) to permitbicyclists to cross at right angles. If this is notpossible, consider using special construction andmaterials to keep the flangeway depth and widthto a minimum.

Seen Figure 1020-9 and the MUTCD for thesigning and marking for a shared use pathcrossing a railroad track.

Railroad Crossing for Shared Use PathFigure 1020-9

R15-1

W10-1

15

m4

.5 m

15

m

Sh

are

d u

se

pa

th

RR

C R O

S S

I N G

R A I L

ROAD

Design Manual Bicycle FacilitiesMay 2001 Metric Version Page 1020-13

(e) Separation, Barrier, and Fencing. Whenpossible, provide a wide separation between ashared use path and the traveled way where thepath is located near the traveled way.

If the shared use path is inside the Design ClearZone, provide a traffic barrier. (See Chapter 700,“Roadside Safety,” for Design Clear Zone. SeeChapter 710, “Traffic Barriers,” for barrierlocation and deflection.) A concrete barrierpresents less of a hazard to bicyclists than aW-beam guardrail and is preferred. However, ifthe edge of the path is farther than 3.0 m from thebarrier, a W-beam guardrail is also acceptable.

If the roadway shoulder is less than 1.8 m wide andthe edge of path is within 1.5 m of a barrier, providea taller barrier (minimum of 1.1 m) to reduce thepotential for bicyclists falling over the barrier intothe traveled way. If the roadway shoulder is morethan 1.8 m wide and the edge of path is more than1.5 m from a barrier, a standard height barrier maybe used.

Where the path is to be located next to a limitedaccess facility, there is also a need for an accessbarrier. Where space permits, fencing, as isdescribed in Chapter 1460, can be provided inconjunction with a standard height barrier.Otherwise, provide a taller barrier (1.37 mminimum height). Provide a taller barrier (1.37 mminimum) on structures specifically designed forbicycle use as is shown on Figure 1020-16.

Fencing between a shared use path and adjacentproperty may also be necessary to restrict accessto the private property. Discuss the need forfencing and the appropriate height with theproperty owners during project design.

Consider the impacts of barriers and fencing onthe sight distances.

(f) Design Speed. The design speed for ashared use path is dependent on the expectedconditions of use and on the terrain. See Figure1020-10 for values.

Design Speed Min. CurveConditions MPH Radius M

Open country (level or 20 22.5undulating); separate shareduse path in urban areas

Long down grades 30 49.5(steeper than 4% andlonger than 500 ft)

Bicycle Design SpeedsFigure 1020-10

(g) Horizontal Alignment andSuperelevation. A straight 2% cross slope ontangent path sections is recommended. This isthe maximum superelevation used. A greatersuperelevation can cause maneuvering difficultiesfor adult tricyclists and wheelchair users.

Increase pavement width up to 1.2 m on the insideof a curve to compensate for bicyclist lean.(See Figure 1020-11.) In sharp curve conditions,consider center line pavement marking on twoway facilities.

AdditionalPavement

Radius Width

0 m to 7.5 m 1.2 m

7.5 m to 15 m 0.9 m

15 m to 22.5 m 0.6 m

22.5 m to 30 m 0.1 m

30 m + 0 m

Bikeway Curve WideningFigure 1020-11

Standard bikeway curve widening

Bicycle Facilities Design ManualPage 1020-14 Metric Version May 2001

(h) Stopping Sight Distance. Figure 1020-19indicates the minimum stopping sight distancesfor various design speeds and grades. The valuesare based on a 1.4 m eye height for the bicyclistand 0 m height for the object (roadway surface).On grades, the descending direction controls thedesign for two-way shared use paths. (Passingsight distance is not considered due to the rela-tively low speed of bicyclists. Intersection sightdistance is not a consideration because of thepresence of either signals or stop signs atroadway crossings.)

(i) Sight Distance of Crest Vertical Curves.Figure 1020-20, Sight Distance for Crest VerticalCurves, indicates the minimum lengths of crestvertical curves for varying design speeds.

(j) Lateral Clearance on Horizontal Curves.Figure 1020-21 indicates the minimum clearancesto line-of-sight obstructions for horizontal curves.Obtain the lateral clearance by entering, on thechart, the stopping sight distance from Figure1020-19 and the proposed horizontal curveradius. Where minimum clearances cannot beobtained, provide standard curve warning signsand use supplemental pavement markings inaccordance with the MUTCD.

(k) Grades. Some bicyclists are unable tonegotiate long, steep uphill grades. Long down-grades can also cause problems on shared usepaths. The maximum grade recommended fora shared use path is 5%. It is desirable thatsustained grades (245 m or longer) be limitedto 2% to accommodate a wide range of users.

The following grade length limits are suggested:

5-6% for up to 245 m7% for up to 120 m8% for up to 90 m9% for up to 60 m10% for up to 30 m11+% for up to 15 m

Grades steeper than 3% might not be practicablefor shared use paths with crushed stone or otherunpaved surfaces for both bicycle handling andtraction, and for drainage and erosion reasons.

Options to mitigate steep grades are:

• When using a steeper grade add an additional1.2 to 1.8 m of width to permit slower speedmaneuverability and to provide a place wherebicyclists can dismount and walk.

• Use signing in accordance with MUTCD toalert bicyclists of the steep down grades andthe need to control their speed.

• Provide adequate stopping sight distance.

• Increase horizontal path side clearances(1.2 to 1.8 m is recommended), and provideadequate recovery area and/or bike rails.

(l) Pavement Structural Section. Design thepavement structural section of a shared use pathin the same manner as a highway, considering thequality of the subgrade and the anticipated loadson the bikeway. Principle loads will normally befrom maintenance and emergency vehicles.

Unless otherwise justified, use asphalt concretepavement (ACP) in the construction of a shareduse path. Asphalt concrete pavement is to be0.60 mm thick.

Contact the Materials Laboratory for determina-tion of the subgrade R value.

SubsurfacingR Value Thickness (mm)

< 40 0.105

40 to 65 0.75

> 65 0.60

R Values and Subsurfacing NeedsFigure 1020-12

(m) Structures. Structures intended to carrya shared use path only are designed using pedes-trian loads and emergency and maintenancevehicle loading for live loads. Provide the sameminimum clear width as the approach pavedshared use path, plus the graded clear areas.See Figure 1020-13 for path and graded areas.

Carrying full widths across all structures has twoadvantages:

Design Manual Bicycle FacilitiesMay 2001 Metric Version Page 1020-15

• The clear width provides a minimum hori-zontal shy distance from the railing or barrier.

• It provides needed maneuvering room toavoid pedestrians and other bicyclists whohave stopped on the bridge.

Undercrossings and tunnels are to have a mini-mum vertical clearance of 3.0 m from the bikewaypavement to the structure. This allows access byemergency, patrol, and maintenance vehicles onthe shared use path.

See Figure 1020-16 for barrier and rail placementon bridges. Consult with Maintenance and theBridge Preservation Office to verify that thesewidths are adequate for their needs. If not, widento their specifications.

Provide a smooth, nonskid surface for bicycles totraverse bridges with metal grid bridge decking.The sidewalk may be used as a bikeway or placesigns instructing the bicyclist to dismount andwalk for the length of a bridge with this typeof decking.

Use bicycle-safe expansion joints for all deckswith bikeways.

(n) Drainage. Sloping the pavement surface toone side usually simplifies longitudinal drainagedesign and surface construction and is the pre-ferred practice. (See 1020.05(2)(g) for maximumpermitted slope.) Generally, surface drainagefrom the path will be adequately dissipated as itflows down the gently sloping shoulder. How-ever, a shared use path constructed on the sideof a hill might require a drainage ditch on theuphill side to intercept the hillside drainage.Where necessary, install catch basins withdrains to carry intercepted water under the path.Refer to Chapter 1210 for other drainage criteria.

Locate drainage inlet grates and manhole coversoff the pavement of shared use paths. If manholecovers are needed on a path, install them tominimize the effect on bicyclists. Manhole coversare installed level with the surface of the path.

Drainage inlet grates on bikeways must haveopenings narrow enough and short enough toensure that bicycle tires will not drop into thegrates. Where it is not immediately feasible to

replace existing grates with standard gratesdesigned for bicycles or where grate cloggingis a problem, steel cross straps may be installedwith a spacing of 150 to 200 mm on centers, toadequately reduce the size of the openings.

(o) Bollards. Install bollards at entrances toshared use paths to prevent motor vehiclesfrom entering. When locating such installations,ensure that barriers are well marked and visibleto bicyclists, day or night. Installing reflectors orreflectorized tape are ways to provide visibility.See Standard Plan H-13 Type 1 Bollard.

A single bollard installed in the middle of thepath reduces the users’ confusion. Where morethan one post is necessary, use 1.5 m spacing topermit passage of bicycle-towed trailers,wheelchairs, and adult tricycles and to ensureadequate room for safe bicycle passage withoutdismounting. Design bollard installations so theyare removable to permit entrance by emergencyand service vehicles, and with breakaway featureswhen in the Design Clear Zone. Ensure that thebollard sleeve is flush with pavement surface.

(p) Signing and Pavement Markings. Refer tothe MUTCD for guidance and directions forsigning and pavement markings for bikeways.Consider a 100 mm yellow center line to separateopposing directions of travel where there is heavyuse, on curves where there is restricted sightdistance, and where the path is unlighted andnighttime riding is expected. A 100 mm white lineon each edge of the path helps to delineate the pathif nighttime use is expected. Lateral and verticalclearance for signs is shown on Figure 1020-13.

(q) Lighting. The level of illumination requiredon a bicycle facility is dependent upon theamount of nighttime use expected and the natureof the area surrounding the facility Refer toChapter 840 for additional guidance concerningillumination of bikeways. Bikeway/roadwayintersection lighting is recommended.

(3) Design Criteria for Bike Lane(a) Widths. Some typical bike lane configura-tions are illustrated in Figure 1020-15 and aredescribed below:

Bicycle Facilities Design ManualPage 1020-16 Metric Version May 2001

Figure 1020-15, Design A, depicts bike lanes onan urban-type curbed street where parking stalls(or continuous parking stripes) are marked.Locate bike lanes between the parking area andthe traffic lanes. Minimum widths are shown.

Do not place bike lanes between the parking areaand the curb. Such facilities create hazards forbicyclists, such as opening car doors and poorvisibility at intersections. Also, they preventbicyclists from leaving the bike lane to turn leftand they cannot be effectively maintained.

Figure 1020-15, Design B, depicts bike lanes onan urban-type curbed street, where parking ispermitted. Establish bike lanes in conjunctionwith the parking areas. As indicated, 3.6 m is theminimum width of the bike lane where parking ispermitted. This type of lane is satisfactory whereparking is not extensive and where turnover ofparked cars is infrequent. However, an additionalwidth of 0.3 to 0.6 m is recommend if parking issubstantial or turnover of parked cars is high.

Figure 1020-15, Design C, depicts bike lanesalong the outer portions of an urban-typecurbed street where parking is prohibited. Thisconfiguration eliminates potential conflicts withmotor vehicle parking. Opening car doors is anexample. Minimum widths are shown. Bothminimum widths shown must be achieved. Witha normal 0.6 m gutter, the minimum bike lane widthis 1.5 m. Post NO PARKING signs when necessary.

Figure 1020-15, Design D, depicts bike lanes ona highway without curbs and gutters. Minimumwidths are shown. Additional width is desirable,particularly where motor vehicle operating speedsexceed 40 mph.

High-speed truck, bus, and recreational vehicletraffic can cause problems along a bike lanebecause of aerodynamic effects and vehiclewidths. Increase shoulder width to accommodatethe large vehicles and bicycle traffic when 5%or more of the daily traffic is truck, bus, orrecreational vehicle traffic.

Bike lanes are not advisable on long, steepdowngrades where bicycle speeds greater than30 mph can be expected. As grades increase,downhill bicycle speeds will increase, whichincreases the handling problems if riding near the

edge of the roadway. In such situations, bicyclespeeds can approach those of motor vehicles, andCategory A bicyclists will generally move intothe motor vehicle lanes to increase sight distanceand maneuverability. However, Category B & Cbicyclists might be placed in a hazardous posi-tion, thus signing in accordance with theMUTCD is needed to alert them of the gradeand the need to control their speeds.

Bike lanes are usually placed on the right sideof one-way streets. Consider placing the bikelane on the left side only when it produces fewerconflicting movements between bicycles andmotor vehicles.

(b) Intersection and Signal Design. Mostmotor vehicle/bicycle collisions occur at inter-sections. For this reason, design bike lanes atintersections in a manner that will minimizeconfusion for motorists and bicyclists and willpermit both users to operate in accordance withthe Rules of the Road. (RCW 46.61)

Figure 1020-22 illustrates a typical intersectionof multilane streets, with bike lanes on allapproaches. Some common movements of motorvehicles and bicycles are shown. At intersectionswhere there are bike lanes and traffic signals,consider the installation of loop detectors withinthe bike lane (in advance of the intersection).Select loop detectors sensitive enough to detectbicycles. Bicyclists generally prefer not to usepush button actuators, as they must go out of theway to actuate the signal. For additional guidanceon signal design at intersections involving bikelanes, refer to Chapter 850.

Figures 1020-23a and b illustrate two pavementmarking pattern options where bike lanes crossfreeway off and on-ramps. Option 1 provides adefined crossing point for bicyclists that wantto stay on their original course. This option isdesirable when bicyclists for various reasons donot have a good view of traffic. Use Option 2where bicyclists normally have a good view oftraffic entering or exiting the roadway and willadjust their path to cross ramp traffic. A bikecrossing sign is intended for use on highwaysto warn motorists of the possibility of bicyclistscrossing the roadway.

Design Manual Bicycle FacilitiesMay 2001 Metric Version Page 1020-17

Dashed lines across the off-ramp are notpermitted.

Figure 1020-24 illustrates the recommendedpavement marking patterns where bike lanescross a channelized right turn only lane. Whenapproaching such intersections, bicyclists willhave to merge with right-turning motorists. Sincebicyclists are typically traveling at speeds lessthan motorists, they can signal and merge wherethere is a sufficient gap in right-turning traffic,rather than at any predetermined location. Forthis reason, it is most effective to eliminate alldelineations at the approach of the right turn lane(or off-ramp) or to extend a single, dashed bikelane line at a flat angle across the right turn lane.A pair of parallel lines (delineating a bike lanecrossing) to channelize the bike merge is notrecommended as this encourages bicyclists tocross at a predetermined location. In addition,some motorists might assume they have theright of way and neglect to yield to bicyclistscontinuing straight.

A dashed line across the right-turn-only lane isnot recommended where there are double right-turn-only lanes. For these types of intersections,drop all pavement markings to permit judgmentby the bicyclists to prevail.

(c) Traffic Signals. At signalized intersections,consider bicycle traffic when timing the trafficsignal cycle and when selecting the method ofdetecting the presence of the bicyclist. Contactthe region’s Bicycle Coordinators for assistancein determining the timing criteria.

(d) Signing and Pavement Markings. Usethe general guidelines in the MUTCD, Part IX,and the Washington State Modifications to theMUTCD for acceptable signing and pavementmarking criteria. Additional guidelines areshown on Figures 1020-15, 1020-25, and1020-26. Lateral and vertical clearance forsigns is shown on Figure 1020-13.

(f) Drainage Grates and Manhole Covers.Locate drainage inlet grates and manhole coversto avoid bike lanes. When drainage grates ormanhole covers are located on a bike lane,minimize the effect on bicyclists. A minimum

of 0.9 m of lateral clearance is needed between theedge of a drainage inlet grate and the shoulderstripe. Install and maintain grates and manholecovers level with the surface of the bike lane.

For more information see 1020.05(2)(n).

(4) Design Criteria for SharedRoadwayAny improvements for motor vehicle traffic on ashared roadway will also improve the travelingconditions for bicycles.

A shared roadway designated as a bike routeoffers a greater degree of service to bicycliststhan other roadways. Establish a bike route byplacing the MUTCD Bicycle Route signs ormarkers along the roadway. Improvements mighthave to be made for safer bicycle travel. Someimprovements for facilitating better bicycle travelare widening the shoulders using the shouldercriteria in Chapter 430 “Modified Design Level”and 440 “Full Design Level” , adding pavementmarkings, improving roadside maintenance,removing surface hazards such as drain grates notcompatible with bicycle tires, and other facilitiesto provide better traveling for bicyclists.

1020.06 DocumentationThe following documents are to be preserved inthe project file. See Chapter 330.

� Justification for reduction of roadway crosssections

� Justification for reduction of bikeway crosssections

� New or major improvement projects wherebike lanes or bike paths are not accommo-dated (except where prohibited).

Bicycle Facilities Design ManualPage 1020-18 Metric Version May 2001

NOTE:

(1) Use 3.6 to 4.2 m when maintenance vehicles use a shared use path as an access road for utilities.Use of 3.6 to 4.2 m paths is recommended when there will be substantial use by bicycles (≥ 60bicycles per day), or joggers, skaters, and pedestrians (20 per hour). Contact region’s BicycleCoordinator for bicycle use information. See 1020.05(2)(a) for more discussion on bicycle pathwidths.

(2) Where the paved width is wider than the minimum required, reduce the graded area accordingly.

Two-Way Shared Use Path on Separate Right of WayFigure 1020-13

Bike path1.2

m m

in,

1.5

mm

ax

0.9 m min,1.8 m max

2%

Rounding required forslopes steeper than 1V:4H

area (2)0.6 m graded

3 m min bike path (1) area (2)0.6 m graded

3.6 m is preferred, thisallows for future trafficincreases

Design Manual Bicycle FacilitiesMay 2001 Metric Version Page 1020-19

For Notes (1) and (2) see Figure 1020-13

See 1020.05(2)(e) for selecting barriers between bicycle path and shoulder and the need for fencing onlimited access roadways.

Two-Way Shared Use Path Adjacent to RoadwayFigure 1020-14

2%

3.0 m min bike path (1)

Bike path

Rounding required forslopes steeper than 1V:4H

Highway

0.6 m graded

area (2)

0.6 m gradedarea (2)

Highway Shoulder

Shoulder

3.6 m is preferred, thisallows for future trafficincreases

Traffic Barrier

Varies with the amount of rightof way obtainable. 0 m min.

Bicycle Facilities Design ManualPage 1020-20 Metric Version May 2001

Note:

(1) The optional solid white line might be advisable where stalls are unnecessary (because parking islight) but there is concern that motorists might misconstrue the bike lane to be a traffic lane.

(2) 3.9 m to 4.3 m is recommended where there is substantial parking or turnover of parked cars is high.

(3) If rumble strips exist, provide 1.2 m minimum from the rumble strips to the outside edge of theshoulder.

Typical Bike Lane Cross SectionsFigure 1020-15

200 mm Solid whitestripe (1)

Parking stalls or optional 100 mm solidline

1.5 m min1.5 m min

3.6 m min (2)

200 mm Solid whiteline

BikeLane

BikeLane

Motor Vehicle Lanes

Motor Vehicle Lanes

Motor Vehicle Lanes

Bike LaneBike Lane

ParkingParking

Design A marked parking

200 mm Solid whiteline

Design B parking permitted without parking line or stall

Design C parking prohibited

BikeLane

1.2 m minMotor Vehicle Lanes

200 mm Solid whiteline

BikeLane

1.2 m min

Rumblestrips (3)

Design D typical roadway

1.5 m min

1.2 m min w/ocurb and gutter

Post NO PARKING signs as required

3.6 m min (2)

Design Manual Bicycle FacilitiesMay 2001 Metric Version Page 1020-21

Note:

The above applies to bike lanes and shared use paths. The 0.81 m barrier is used for shared useroadways.

Bikeways on Highway BridgesFigure 1020-16

Edge of path

Separated (shared use paths only)

0.8

1 m

1.3

7 m

0.8

1 m

Unseparated (bike lanes and shared roadway)

Bicyclists use the shoulder between the edgeof traveled way and the bridge rail.

Edge of traveled way

1.3

7 m

1.3

7 m

Bicycle Facilities Design ManualPage 1020-22 Metric Version May 2001

Refuge AreaFigure 1020-17

Y

X

Shared use path

L

L

Roadway

Raisedisland(typ)

Cut throughat grade

Shared use path

W (offset) = Y/2

L = 0.62WV, where V 70 km/h≥

L = 155, where V < 70 km/h

2

Y = Width of refuge

2.0 m = poor

2.5 m = satifactory

3.0 m = good

WV

L = Length of island

should be 6 ft or greater

X = Length of island sould

be 2 m or greater

Design Manual Bicycle FacilitiesMay 2001 Metric Version Page 1020-23

Note:

Provide additional width to 4.2 m to be provided at railroad crossing to allow bicyclists to choose theirown crossing routes.

At-Grade Railroad CrossingsFigure 1020-18

Widen to permitright angle crossing

45o Crossing

(acceptable)

Bikeway

Railro

ad

R/W

Railro

ad

R/W

ShoulderBikeway

2.4 mmax2.4 m

max

Hig

hw

ay R

/W

Widened Shoulder

Roadway CL

Large radii desirable

Large radii desirable

Striped

Bikeway

Direction ofbicycle travel

Shoulder

RR Tracks

90o Crossing

(most desirable)

Bikeway

Railro

ad

R/W

CurveWidening

Additional R/Wrequired

CurveWidening

Additional R/Wrequired

Shoulder

Railro

ad

R/W

Bikeway

Bicycle Facilities Design ManualPage 1020-24 Metric Version May 2001

Stopping Sight DistanceFigure 1020-19

S = Stopping Sight Distance, m.

V = Velocity, km/h

f = Coefficient of Friction (use 0.25)Where:

V VS =

2

- G+ )

Descend (-G)

Gra

de -

%

0 15 30 150 60 75 90 105 120

15

10

5

0

20

16 k

m/h

25 k

m/h

30 k

m/h

40 k

m/h

25 k

m/h

40 km/h

50 k

m/h

50 km/h

135

254 (f

G = Grade m/m (rise/run)

Stopping Sight Distance (m)(based on 2.5 seconds reaction time)

Ascend (+G)

30 km/h16 k

m/h

+1.4

Design Manual Bicycle FacilitiesMay 2001 Metric Version Page 1020-25

Sight Distances for Crest Vertical CurvesFigure 1020-20

Where:

S = Stopping sight distance.A = Algebraic difference in grade.

h2 = 0 m (height of object)

L = Minimum vertical curve length.

h1 = 1.4 m (eye height of cyclist)

when S < L

0

10

20

30

0 30 60 90 120 150 180 210 240

Minimum length of vertical curve (m)

Alg

eb

raic

dif

fere

nce in

gra

de

L =

2h + 2h2

2

100 ( )

AS2

1

AL = 2S - when S > L

+ )h h(2001 2

2

50 km/h S

= 69 m

40 km

/h S

= 52

.5 m30 k

m/h

S =

36.

6 m

25 k

m/h

S

= 2

5.5

m

16 k

m/h

S

= 1

5 m

Bicycle Facilities Design ManualPage 1020-26 Metric Version May 2001

Lateral Clearance on Horizontal CurvesFigure 1020-21

Height of eye: 1.4 mHeight of object: 0.0 mLine of sight is normally 0.6 m abovecenter line of inside lane at point ofobstruction provided no vertical curveis present in horizontal curve.

Center of lane

Obstruction orback slope

Line ofsight

Sight distance (S)

Radius

M

Where:S = Sight distance in metersR = Radius of center line inside lane in metersm = Disance from center line inside lane in meters

S ≤ Length of curveAngle is expressed in degrees

M R 1 COS28.65 S

R= −

SR

28.65COS

1 R M

R= − −

0

3

6

9

12

15

30

45

60

75

90

10

5

12

0

13

5

15

0

16

5

18

0

19

5

21

0

22

5

24

0

25

5

27

0

Curve Radius (m)

Late

rial C

leara

nce O

bstr

uc

tio

n,

M (

m)

S = 15S = 22.5 S = 30S = 45S = 60

S = 90

S = 75

S = 105

Design Manual Bicycle FacilitiesMay 2001 Metric Version Page 1020-27

Typical Bicycle/Auto Movements at Intersection of Multilane StreetsFigure 1020-22

LEGEND

Bike Travel

Motor Vehicle Travel

Pede

stria

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Cross

ing

Pede

stria

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Cross

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Bicycle Facilities Design ManualPage 1020-28 Metric Version May 2001

Bicycle Crossing of Interchange RampFigure 1020-23a

R3-17

W11-1

Option 1

Option 2

Exit Ramp

Exit Ramp

Cross Street

Cross Street

W11-1

R3-17

R3-17

R3-17

RIGHTLANE

ONLY

RIGHTLANE

ONLY

RIGHTLANE

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RIGHT

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Design Manual Bicycle FacilitiesMay 2001 Metric Version Page 1020-29

Bicycle Crossing of Interchange RampFigure 1020-23b

R3-17

R3-17

W11-1

Option 1

Option 2

Exit Ramp

Exit Ramp

Cross Street

Cross Street

W11-1

R3-17

R1-2 R3-17YIELD

RIGHT

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ONLY

RIGHT

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ONLY

RIGHT

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ONLY

RIGHT

LANE

ONLY

1020-23b.vsd

Bicycle Facilities Design ManualPage 1020-30 Metric Version May 2001

Note:

(1) If space is available.

(2) Optional dashed line. Not recommended where a long right-turn-only lane or double turnlanes exist.

(3) Otherwise, drop all delineation at this point.

(4) Drop bike lane line where right-turn-only designated.

Bike Lanes Approaching Motorists’ Right-Turn-Only LanesFigure 1020-24

Ped. Crossing Ped. Crossing

Typical pathof throughbicyclist.

PARKING AREA BECOMESRIGHT-TURN-ONLY LANE

RIGHT-TURN-ONLY LANE

Ped. Crossing

Typical pathof throughbicyclist.

Ped. Crossing

RIGHT LANE BECOMESRIGHT-TURN-ONLY LANE

OPTIONAL DOUBLERIGHT-TURN-ONLY LANE

1.2 m min 1.2 m min

1.2 m minTypical pathof throughbicyclist.

(1)(1)

See Note (2)

See Note (3)

See Note (4)

(1)

Design Manual Bicycle FacilitiesMay 2001 Metric Version Page 1020-31

Note:

(1) 15 to 60 m dotted line if bus stop or heavy right-turn volume, otherwise solid line.

(2) Dotted line for bus stops immediately beyond the intersection is optional; otherwise use 200 mmsolid line

Typical Pavement Marking for Bike Lane on Two-Way StreetFigure 1020-25

R3-17R7 series sign

(as appropriate)

200 mm solidline

Optional 100 mmsolid line

R3-17R7 series sign

(as appropriate)

200 mmsolid line

R3-17R8-3a

Signalized Intersection

Minor Intersection

Ty

pic

al

ap

pli

ca

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he

re p

ark

ing

perm

itte

d

Ty

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al

ap

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he

re p

ark

ing

pro

hib

ited

See Note (1)

See Note (1)

See Note (2)

R3-17R8-3a

RIGHT

LANE

ONLY

P

RIGHT

LANE

ONLY

1020-25M.vsd

Bicycle Facilities Design ManualPage 1020-32 Metric Version May 2001

Typical Bike Lane Pavement Markings at T-IntersectionsFigure 1020-26

T-Intersection

with no painted crosswalks

T-Intersection T-Intersection

with bus stopsand painted crosswalks

Bus Stop

Bus Stop Bus Stop

with painted crosswalksand no bus stops

Design Manual Pedestrian Design ConsiderationsMay 2001 Metric Version Page 1025-1

1025 Pedestrian Design Considerations

Roadside Manual, M 25-30, WSDOT

Sidewalk Details, WSDOT, 2000

Standard Plans for Road, Bridge, and MunicipalConstruction (Standard Plans), M 21-01,WSDOT

Pedestrian Facilities Guidebook, incorporatingPedestrians into Washington’s TransportationSystem, OTAK, 1997

1025.03 Definitionsaccessible route An unobstructed pedestrianroute that meets the requirements of theAmericans with Disabilities Act accessibilityguidelines.

ADA An abbreviation for the Americans withDisabilities Act of 1990. The ADA is a civilrights law that identifies and prohibits discrimina-tion based on disability. The ADA requires publicentities to design new facilities or alter existingfacilities, including sidewalks and trails that areaccessible to people with disabilities. Preserva-tion projects, usually, are not considered analteration of existing facilities. Accessibilitycan be addressed in preservation projects as aspot safety improvement.

bulb out A curb and sidewalk bulge orextension out into the roadway used to decreasethe length of a pedestrian crossing.

crosswalk That marked or unmarked portion ofa roadway designated for a pedestrian crossing.

landing A level area at the top of a pedestrianramp.

midblock pedestrian crossing A markedpedestrian crossing located between intersections.

pedestrian facilities Walkways such as side-walks, highway shoulders, walking and hikingtrails, shared use paths, pedestrian grade separa-tions, crosswalks, and other improvementsprovided for the benefit of pedestrian travel.

pedestrian-friendly A term for an environmentthat is safe, pleasant, and inviting to pedestrians.

1025.01 General1025.02 References1025.03 Definitions1025.04 Policy1025.05 Pedestrian Human Factors1025.06 Pedestrian Activity Generators1025.07 Pedestrian Facility Design1025.08 Documentation

1025.01 GeneralPedestrians are present on most highways andtransportation facilities, yet their travel modediffers vastly and sometimes is in conflict withthe requirements for vehicular travel. The chal-lenge is to provide safe and efficient facilities thataddress these two competing interests within alimited amount of right of way. Sidewalks andtrails serve as critical links in the transportationnetwork. Facilities that encourage pedestrianactivities are a part of comprehensive transpor-tation planning and development programs forurban and rural communities.

1025.02 ReferencesDesign Guidance, Accommodating Bicycle andPedestrian Travel. A Recommended Approach,USDOT Policy Statement, 2001

Manual on Uniform Traffic Control Devicesfor Streets and Highways (MUTCD), USDOT,Washington DC, 1988, including the WashingtonState Modifications to the MUTCD, M 24-01,WSDOT, 1996

RCW 46.04.160, “Crosswalk”

RCW 46.61.240, “Crossing at other thancrosswalks”

RCW 47.24.010, City streets as part of statehighways, “Designation-construction,maintenance-return to city or town”

RCW 47.24.020, City streets as part of statehighways, “Jurisdiction, control”

HOV Direct Access Design Guide, M 22-98,WSDOT

Pedestrian Design Considerations Design ManualPage 1025-2 Metric Version May 2001

pedestrian refuge island A raised area betweentraffic lanes that provides a place for pedestriansto wait to cross the street.

raised median A raised island in the center ofa road used to restrict vehicle left turns and sidestreet access. Pedestrians often use this medianas a place of refuge when crossing a roadway.

1025.04 Policy(1) GeneralPedestrian facilities are required along and acrossmost sections of state routes and are an integralpart of the transportation system. Walkways andother pedestrian facilities are considered in theproject definition phase. The only factors thatwill preclude providing pedestrian facilities ina project are as follows:

• Pedestrians are prohibited by law from usingthe facility.

• The cost of the improvements is excessiveand disproportionate to the original need orprobable use (as a guide, more than 20% ofthe original estimate).

• Low population density or other factorsindicate that there is no need.

(2) Funding ProgramsThe adequacy of appropriate pedestrian facilitiesis addressed in mobility, safety, bridge replace-ment, and economic initiative projects in both theHighway Capitol Improvement and PreservationPrograms. Federal, state, and local funds areavailable for pedestrian facility projects.

(a) Improvement Program

Mobility Program (I-1). Pedestrian facilities areincluded in improvement projects in urban areasunless the facility is restricted to motor vehicleuse. In urban areas, pedestrian facilities caninclude traffic control devices, grade separations,crosswalks, sidewalks, and illumination. Othertechnologies, design features, or strategies, suchas creating a pedestrian-friendly atmosphere, aregenerally beyond the scope of usual highwayconstruction projects. These design features,however, can be included in a highway projectwhen a local agency desires to participate and

can provide the necessary funding. Partnershipagreements between the state and local agenciesto provide pedestrian amenities are effectiveways to address seemingly different goals.

In rural areas, paved roadway shoulders areusually sufficient as pedestrian facilities. In highpedestrian use areas adjacent to the highway(state parks, recreation areas, and public-ownedparking lots) additional signing, marked cross-walks, and separate pedestrian paths and trailsmight be necessary. Separate pedestrian paths ortrails are appropriate, in some circumstances, asconnections between activity centers or as partof a comprehensive trails plan.

Safety Program (I-2). Pedestrian AccidentLocations (PALs) are sections of state routes withfour or more pedestrian collisions with vehiclesin a six-year period. PALs usually have a highsocietal cost and compete favorably with HighAccident Locations (HALs) for safety funding.

Pedestrian Risk Projects are sections of statehighways that have a high risk of pedestriancollisions with vehicles based on adjacent landuse, roadway geometric design, and trafficconditions. Each region has a funding allotmentto address pedestrian risk locations. Short sec-tions of sidewalks, illumination, raised medians,and other pedestrian facilities are eligible forsafety funding where there are pedestrian colli-sions, such as part of PAL or a High AccidentCorridor (HAC).

Economic Initiatives (I-3). Projects supportingtourism development, promoting the interpreta-tion of heritage resources, and ensuring publicaccess to rest room equipped facilities caninclude limited pedestrian facility improvementsif the site generates pedestrian activity.

(b) Preservation Program

Roadway Program (P-1). Projects fundedby the Highway Capitol Preservation Programusually do not include enhancement of existingpedestrian facilities except as minor pedestrianspot safety improvements. Other funding sources,including local agency participation throughfederal grants, can be used for sidewalks,walkways, or other pedestrian facilities inthese projects.

Design Manual Pedestrian Design ConsiderationsMay 2001 Metric Version Page 1025-3

Structures Program (P-2). Bridge replacementfunding can be used to replace existing pedestrianfacilities or to match shoulder width or sidewalksof adjacent roadways on bridges.

Other Facilities (P-3). This funding sourcecan be used to refurbish pedestrian facilitiesand address ADA requirements within existingrest areas.

(3) Project RequirementsFor urban mobility improvement projects(Pedestrian connectivity projects in the matrices,Chapter 325), apply the guidance in this chapterto the pedestrian facility.

For highway design elements affected by theproject, apply the appropriate design level(Chapter 325) and design requirements in theapplicable Design Manual chapters.

For highway design elements not affected by theproject, no action is required.

1025.05 Pedestrian HumanFactorsUnderstanding the human behavior of pedestriansaids in the design of effective facilities. Youngchildren tend to dart out into traffic because theyhave no understanding of vehicle stoppingdistances or sight limitations. Older children andteenagers are more likely to cross midblock, orstep out in front of oncoming traffic. Adults aremore capable of perceiving and dealing with risk.Senior adults and persons with disabilities aremost likely to obey crosswalk laws and makepredictable movements. Senior pedestrians, as agroup, also tend to have reduced vision, balance,speed, stamina, and have trouble distinguishingobjects in low light and nighttime conditions.

Walking rates are an important consideration inintersection design. The average walking speedfor pedestrians is 1.2 m per second. Actualwalking speeds, however, can vary from 0.7 to1.8 m per second depending on the age group.In addition, people with disabilities require moretime to cross a roadway. In areas with a highersenior adult population, a walking rate of 0.9 mper second is more realistic. This can be miti-gated at locations with traffic signals by

providing longer pedestrian signal timings,or pedestrian refuge areas, such as islandsand medians.

Factors that contribute to deterring pedestriantravel include:

• High vehicle volumes and speeds

• Lack of separated pedestrian facilities

• Lack of a continuous walkway system(missing links)

• Poor nighttime lighting

• Lack of connections to pedestrian activitygenerators

• Inaccessible to people with disabilities

• Concerns for personal safety

• Barriers on walking route (rivers, railroads,bridges without sidewalks)

• Narrow walkway width

• Lack of transit shelter

To encourage multimodal transportation, livablecommunities, and pedestrian safety, manyagencies provide pedestrian-friendly featuresalong their streets, roads, and highways. Thefollowing are several pedestrian-friendlypractices in current use:

• ADA accessible routes

• More direct alignment of walkways to reducetravel distances

• A complete network of pedestrianconnections

• Ramps and handrails for persons with disabilities

• Medians and pedestrian refuge islands

• Buffers between the walkway and roadway

• Lower vehicular speeds

• Adequate pedestrian signs, signals, andmarkings

• Pedestrian furniture and vegetation

• Bulb outs or curb extensions

• Adequate illumination

• Audible warning signals

Pedestrian Design Considerations Design ManualPage 1025-4 Metric Version May 2001

1025.06 Pedestrian ActivityGeneratorsThe types of land uses that indicate high pedes-trian activity are residential developments withfour or more housing units per 0.4 hectaresinterspersed with multifamily dwellings or hotelslocated within 800 m of other attractions. Theseattractions might be retail stores, schools, recre-ation areas, or senior citizen centers. Certaintypes of businesses, such as “deli-mart” typestores, fast food restaurants, and skateboardparks, can cater to a specific pedestrian agegroup and generate high activity levels.

Information on land use, development, andestimated pedestrian densities is available frommetropolitan planning organizations, regionplanning offices, and city and county planningdepartment comprehensive plans.

School districts designate walking routes forevery elementary school. In general, childrenwithin 1.6 kilometers of the school are requiredto walk unless there are hazardous walkingconditions. Contact the school district’s safetymanager to determine the walking routes, averagestudent age, transit stops, and the distance fromthe school to attractions. Sports, school plays, andother special events occurring after normal schoolhours can also generate exceptionally high levelsof pedestrian activity. Consider the impact ofthese events when providing pedestrian facilities.

1025.07 Pedestrian Facility Design(1) FacilitiesThe type of pedestrian facility provided is basedon local transportation plans, the roadside envi-ronment, pedestrian volumes, user age group,safety-economic analysis, and continuity oflocal walkways along or across the roadway.Sidewalks can be either immediately adjacent tostreets and highways or separated from them bya buffer. Walking trails, hiking trails, and shareduse paths are independently aligned and generallyserve recreational activities.

The type of walkway also depends on the accesscontrol of the highway as follows:

Full Access Control. Walking and hiking trailsand shared use paths within the right of way areseparated from vehicular traffic with physicalbarriers that discourage pedestrians from enteringthe roadway. These trails can connect with othertrails outside the right of way if the access permitis modified. Grade separations are provided whenthe trail crosses the highway.

Partial or Modified Access Control. Walkingand hiking trails and shared use paths are locatedbetween the access points of interchanges orintersections. Pedestrian crossings are usuallyeither at-grade with an intersecting cross roador a grade separation. Midblock pedestriancrossings can be considered at pedestriangenerators when the roadway has predominatelyurban characteristics.

Managed Access Control. In rural areas, pavedshoulders are usually used for pedestrian travel.When pedestrian activity is high, separate walk-ways are provided. Sidewalks are used in urbanareas where there is an identified need for pedes-trian facilities. Trails and paths, separated fromthe roadway alignment, are used to connect areasof community development. Pedestrian crossingsare at-grade.

(2) Pedestrian Travel Along Streetsand Highways(a) General. On state highways within thecorporate limits of cities, the city has the respon-sibility for maintenance of all appurtenancesbeyond the curb. See RCW 47.24.020. Proposedprojects that will damage or remove existingsidewalks or other walkways within the city’sjurisdiction must include reconstruction of thesefacilities. Examples of various types of pedestrianwalkways are shown in Figures 1025-2a and1025-2b.

The minimum clear width required by a personin a wheelchair or a walker is 0.9 m. Utility polesand other fixtures located in the sidewalk can beobstacles for pedestrians with disabilities. Utilitycompany lines, poles, and other fixtures areaccommodated within the right of way. Whenrelocation of these fixtures is necessary in a

Design Manual Pedestrian Design ConsiderationsMay 2001 Metric Version Page 1025-5

project, determine the impact of their newlocation on any pedestrian walkways. Utilityvaults and junction boxes with special lids areused for installations in sidewalks to reducetripping hazards. Improvement projects mightprovide opportunities to eliminate existing poorlylocated utilities that are hazards to pedestrians.

Hanging or protruding objects within the walk-way are also hazards for pedestrians with visualimpairments. The minimum vertical clearance forobjects overhanging a walkway, including signs,is 2.1 m.

Where the walkway is located behind guardrail,protruding guardrail bolts are cut off or a rubrail is installed to prevent snagging on the bolts.These construction requirements are specified inthe contract.

Provide a smooth finish to vertical concretesurfaces adjacent to a pedestrian facility toprevent snagging or abrasive injuries fromaccidental contact with the surface.

(b) Shoulders. Pedestrian activity is usuallyminimal along rural roadways when the adjacentland use is one or less dwelling units per 0.4 hect-are. Determine if the roadway’s shoulders are ofsufficient width and condition to permit safetravel for pedestrians. Paved shoulders arepreferable for an all-weather walking surface.A 1.2 m wide shoulder is acceptable where pedes-trian activity is minor. Wider shoulders, up to2.4 or 3.0 m are desirable along high-speedhighways, particularly when truck volumesare high or pedestrian activity is significant.

(c) Shared Use Paths. Shared use paths areused by pedestrians and bicyclists. Pedestrianfacilities differ from bicycle facilities in theirdesign requirements and goals and they are notalways compatible. A busy sidewalk might notbe safe for bicycle travel and a well-used bikepath might be unsuitable as a pedestrian walk-way. When a shared use path is determined tobe in the best interests of both groups, seeChapter 1020, “Bicycle Facilities,” regardingshared use paths.

(d) Walking and Hiking Trails. Walking andhiking trails are supplemental features and areconsidered on a project-by-project basis. These

trails are less developed than other walkwaysand shared use paths and are usually unpaved.Because of their primitive nature, ADA require-ments for accessibility are far less restrictive.See Figure 1025-1 for trail widths and grades.The clear area is the cross-sectional area of thetrail that is cleared of limbs, exposed roots,brush, and other obstacles that might be ahazard to the hiker.

Clear Trail MaximumArea Width Grade

Walking trail 2.4 m high 1.2 m 10% *& 3.0 m wide

Hiking trail 2.4 m high 0.9 m 10% sustained,& 3.0 m wide 20% (150 m or less)

Trail Width and GradesFigure 1025-1

* Note: When grades of 5% or more are used,provide 1.2 m square resting areas adjacent tothe trail every 150 m.

(e) Sidewalks. Details for raised sidewalksare shown in the Standard Plans. Roadwayclassification and land use are important factorswhen considering sidewalks. Figure 1025-3provides a generalized method of assessing theneed for and adequacy of sidewalks and doesnot establish minimum requirements for theirinstallation. When sidewalks are recommendedfor a particular roadway in this figure, conducta more extensive study to determine if they canbe justified. The most desirable installation forthe pedestrian is a sidewalk separated from thetraveled way by a planted buffer strip. Theminimum width for the sidewalk is 1.5 m and thebuffer is not less than 0.9 m. Where a sidewalk isseparated from the traveled way with only acurb, the minimum sidewalk width is 1.8 m.Wider sidewalks are used in areas of high pedes-trian traffic. Sidewalks 2.4 m or wider are moreappropriate at these locations. In areas withheavy snowfall, snowplows might need to usethe sidewalk for snow storage if there is noadjacent shoulder. Consider wider sidewalksor a sidewalk with a buffer to minimize thedisruption to pedestrian travel.

Pedestrian Design Considerations Design ManualPage 1025-6 Metric Version May 2001

A grade of 8.33% or less is required when thesidewalk is on an independent alignment anddoes not follow an adjacent roadway grade.Sidewalks located adjacent to a street or highwayfollow that facility’s grade and can exceed8.33%. On roadways with prolonged severegrades, consider providing level landings adja-cent to the sidewalk at approximately 150 mintervals as resting areas for people with physicaldisabilities. The cross slope of a sidewalk cannotexceed 2%. More extreme cross slopes aredifficult for people in wheelchairs to negotiate.

The side slope adjacent to the sidewalk is acritical design element. See Figures 1025-2a and2b. On embankment slopes of 1V:4H or flatter,provide a 0.3 m widening at the edge of the side-walk. On steeper embankment slopes provide a1.2 m embankment widening or use a sidewalkdesign with a 0.6 m widening and a raised150 mm high lip at the back edge of the sidewalk.When the adjacent roadway has a posted speed of35 mph or less and there is a vertical drop-off of760 mm or more behind the sidewalk, provide apedestrian railing when embankment widening isnot possible. Pedestrian railings are not designedto withstand vehicular impacts and cannotredirect errant vehicles. When a vertical drop offis present on a higher speed roadway, the DesignClear Zone is the primary consideration and acrash-worthy traffic barrier is required. SeeChapter 700. In some cases, where the walkwayis adjacent to a vertical drop off and is separatedfrom the roadway, consider installing the trafficbarrier between the travel way and the walkway.The pedestrian railing is then installed betweenthe walkway and the vertical drop off.

Provide either raised sidewalks or ramps on theapproaches to bridges when there are raisedsidewalks on the bridge. The ramp is constructedof either asphalt or cement concrete and the slopeof 1V:20H or flatter. These ramps can also beused as a transition from a raised sidewalk downto a paved shoulder. The ramp provides pedes-trian access and mitigates the raised, blunt endof the concrete sidewalk.

(3) Pedestrian Crossings At-GradeWide, multilane streets are difficult forpedestrians to cross, particularly when there are

insufficient gaps in vehicular traffic becauseof heavy volumes. The chart in Figure 1025-4provides guidance in determining feasible pedes-trian crossings based on vehicular traffic volumeand speed. Appropriate additional safety featuresnecessary for the crossing are also recommendedin this chart.

Pedestrian crossings are permitted along thelength of most highways. Pedestrian crossingof all legs of an intersection is also permitted.An illegal pedestrian crossing only occurswhen signs prohibit a particular crossing at anintersection or the crossing occurs between twosignalized intersections. See RCW 46.61.240.Pedestrian crossings of the roadway are inevi-table. Simply prohibiting a crossing withoutproviding a reasonable option is not an effectivesolution and fails to address the pedestrian’sneeds.

Crosswalks, whether marked or not, exist at allintersections. An unmarked crosswalk is the3.0 m wide area across the intersection behind aprolongation on the curb or edge of the throughtraffic lane. See RCW 46.04.160. A markedcrosswalk is required when the intended pedes-trian route is different than that cited in the RCW.See Figure 1025-5. At roundabouts and intersec-tions with triangular refuge islands or offset legs,the desired pedestrian crossings might not beconsistent with the definition of an unmarkedcrosswalk and markings become necessary.Marked crosswalks also clearly define thepedestrian route and permit enforcement ofpedestrian crossing laws.

The standard crosswalk marking consists ofa series of wide white lines aligned with thelongitudinal axis of the roadway. The lines arepositioned at the edges and centers of the trafficlanes to place them out of the normal wheel pathof vehicles. This type of crosswalk is a LadderBar and is shown in the Standard Plans.

Specially textured crosswalks (consisting ofcolored pavement, bricks, or other materials) aresometimes used by local agencies in communityenhancement projects. These crosswalks do notfall within the legal definition of a markedcrosswalk and parallel white crosswalk linesare required to define the crosswalk.

Design Manual Pedestrian Design ConsiderationsMay 2001 Metric Version Page 1025-7

When locating crosswalks at intersections,consider the visibility of the pedestrian fromthe motorist’s point of view. Shrubbery, signs,parked cars, and other roadside appurtenancescan block the motorist’s view of the pedestrian.Figures 1025-6a and 6b illustrate these sightdistance problems.

In urban areas where vehicle speeds are in therange of 25 to 35 mph, a sidewalk bulb out issometimes used to place the pedestrian at a morevisible location. The bulb out also shortens thelength of the pedestrian crossing and reduces thepedestrian’s exposure time. At intersections withtraffic signals, the bulb out can be used to reduceboth pedestrian signal timing and the mast armlengths of the signal supports. Examples ofsidewalk bulb outs are shown in the Figure1025-7. The right turn path of the design vehicleor the vehicle most likely to make this turn is acritical element in determining the size and shapeof the bulb out. Sidewalk bulb outs tend torestrict the width of the roadway and can makeright turns difficult for extremely long trucks.Any proposal to install bulb outs on state high-ways is a deviation that requires approval anddocumentation.

On roadways with two-way left-turn lanes withpedestrian crossing traffic caused by nearbypedestrian generators, consider removing aportion of the turn lane and installing a raisedmedian refuge and a midblock pedestrian cross-ing. The installation of a midblock pedestriancrossing on a state highway, however, is a designdeviation that requires approval and documenta-tion. An example of a midblock crossing isshown in Figure 1025-8.

An engineering study is required when consider-ing a midblock pedestrian crossing on a statehighway. Conditions that might favor a midblockcrossing are:

• Significant pedestrian crossings and substan-tial pedestrian and vehicle conflicts occur.

• The proposed crossing can concentrate orchannel multiple pedestrian crossings to asingle location.

• The crossing is at an approved school cross-ing on a school walk route.

• The adjacent land use creates high concentra-tions of pedestrians needing to cross thehighway.

• The pedestrians fail to recognize the best orsafest place to cross along a highway andthere is a need to delineate the optimallocation.

• There is adequate sight distance for motoristsand pedestrians.

Midblock pedestrian crossings on state highwaysare not desirable at the following locations:

• Immediately downstream (less than 90 m)from a traffic signal or bus stop wheremotorists do not expect a pedestrian to cross.

• Within 180 m of another pedestrian crossing.

• On high speed roadways as noted in Figure1025-4.

• Where pedestrians must cross three or morelanes of traffic in the same direction.

The minimum width of a raised median refugearea is 1.8 m to accommodate people in wheel-chairs. Raised medians are usually too narrow toallow the installation of ramps and a level land-ing. When the median is 4.9 m or less in width,provide a passageway through the median. Thispassageway connects with the two separateroadways and cannot exceed a grade of 5%.

(4) Sidewalk RampsSidewalk ramps are required at all legal crossing.These ramps provide an easily accessible connec-tion from a raised sidewalk down to the roadwaysurface. To comply with ADA requirements,these ramps are at least 0.9 m wide and haveslopes 1V:12H or flatter. Examples of sidewalkramps are shown in the Standard Plans and theSidewalk Details guide.

The lower terminus of the sidewalk ramp isalways located at the beginning of a marked orunmarked crosswalk when separate ramps areused for each direction. Diagonal ramps are usedat the junction of two crosswalks. A separatesidewalk ramp is preferred for each crossingbecause the crossing distance is shorter andpeople with vision impairments have fewer

Pedestrian Design Considerations Design ManualPage 1025-8 Metric Version May 2001

difficulties with this arrangement. Diagonalramps are sometimes necessary when alteringan existing roadway because of right of wayconstraints.

Surface water runoff from the roadway can floodthe lower end of a sidewalk ramp. Determinethe grades along the curb line and provide catchbasins or inlets to prevent the flooding of theramps. Figure 1025-9 shows examples of howdrainage structures are located. Verify that thedrainage structure will not be in the path of awheelchair user.

A level landing is necessary at the top of asidewalk ramp. This landing is provided to allowa person in a wheelchair room to maneuver intoa position to use the ramp or to bypass it. Inalterations of existing roadways, the landingsmust be at least 0.9 m square. In new construc-tion, a 1.2 m square landing is required. Whenright of way constraints are not an issue, providea larger 1.5 m square landing. If the landing isnext to a vertical wall, a 1.5 m wide clear area isdesirable to allow a person in a wheelchair moreroom to maneuver. Examples of these wheelchairmaneuvers are shown in the Sidewalk Detailsguide. When the upper area of a sidewalk rampis adjacent to a vertical wall, a 1.5 m clearancefrom the edge of the ramp to the wall is desirable.

At signalized intersections, the pedestrian pushbuttons are located near the sidewalk ramps forADA accessibility. See Chapter 850, “TrafficControl Signals,” for information on pedestrianrequirements at traffic signal locations.

(5) Pedestrian Grade SeparationsIn areas where heavy pedestrian traffic is presentand opportunities to cross the roadway areinfrequent, consider providing a pedestrian gradeseparation. When considering a pedestrianstructure, determine if the conditions that requirethe crossing are permanent. If there is a likeli-hood that the pedestrian activity generator mightnot exist in the near future, consider less costlysolutions. Locate the grade separated crossingwhere pedestrians are most likely to cross theroadway. A crossing might not be used if thepedestrian is required to deviate significantly

from a more direct route. A structure might beunder-utilized if the additional average walkingdistance for 85 percent of the pedestrians exceeds400 m. It is sometimes necessary to installfencing or other physical barriers to channel thepedestrians to the structure and reduce thepossibility of undesired at-grade crossings.Pedestrian grade separations are more effectivewhen the roadway is below the natural groundline as in a “cut” section. Elevated grade separa-tions, where the pedestrian is required to climbstairs or use long approach ramps, tend to beunder-utilized.

Grade separated structures are proposed duringthe planning stage of a project because of thehigh costs associated with their design andconstruction. Consider grade-separated crossingsunder the following conditions:

• Where there is moderate to high pedestriandemand to cross a freeway or expressway

• Where there is a large number of youngchildren, particularly on schools routes, whoregularly cross a high speed or high volumeroadway

• On streets with high vehicular volumes andhigh pedestrian crossing volumes, andcrossings are extremely hazardous forpedestrians

The Olympia Service Center Bridge andStructures Office designs pedestrian gradeseparation bridges and tunnels on a project-by-project basis. Railings 1070 mm high are providedon pedestrian bridges. The bridge rail is designedso that a 150-mm sphere cannot pass through anypart of the railing. In addition, a 760 to 806 mmhigh handrail is provided for grades greaterthan 5%. The minimum width between therailings of an overhead structure or the verticalwalls of a tunnel is 2.4 m. The minimum overheadclearance for a tunnel is 3.0 m. Protective screen-ing to prevent objects from being thrown froman overhead pedestrian structure is sometimesnecessary. See Chapter 1120, “Bridges.”

The minimum vertical clearance from the bottomof the pedestrian structure to the roadway beneathis 5.3 m. This minimum height requirementcan affect the length of the pedestrian ramps to

Design Manual Pedestrian Design ConsiderationsMay 2001 Metric Version Page 1025-9

the structure. To comply with ADA requirements,a ramp cannot have a grade exceeding 8.33% andthe maximum rise of the ramp cannot exceed760 mm without landings. Landings are a mini-mum of 1.5 m wide and 1.5 m long except thelanding at the bottom of the ramp, which is 1.8 min length. When ramps are not feasible, provideboth elevators and stairways. Stairways aredesigned in accordance with the Standard Plans.

Pedestrian tunnels are an effective method forproviding crossings for roadways located inembankment sections. When possible, designthe tunnel with a nearly level profile to providecomplete vision from portal to portal. Pedestriansare reluctant to enter a tunnel with a depressedprofile because they are unable to see if thetunnel is occupied. Police officers also havedifficulty patrolling depressed profile tunnels.Provide day and nighttime illumination withinthe pedestrian tunnel. Installing gloss-finishedtile walls and ceilings can also enhance lightlevels within the tunnel.

(6) Transit StopsThe location of transit stops is an importantconsideration in providing appropriate pedestrianfacilities. See Chapter 1060, “Transit BenefitFacilities.” A transit stop on one side of a streetusually has a counterpart on the opposite sidebecause transit routes normally function in bothdirections on the same roadway. When passen-gers use this type of route, they will either crossthe street at the beginning of a trip or the endof the return trip. Pedestrian collisions are morefrequent at these locations. When analyzing highpedestrian accident locations, consider thepresence of nearby transit stops and the opportu-nities for a pedestrian to safely cross the street.At-grade midblock pedestrian crossings areeffective at transit stop locations on roadwayswith lower vehicular volumes. Pedestrian gradeseparations are appropriate at midblock locationswhen vehicular traffic volumes prohibit pedes-trian crossings at grade.

School bus stops are typically adjacent to side-walks in urban areas and along shoulders in ruralareas. Determine the number of children usingthe stop and provide an appropriate waiting area.Children, because of their smaller size, might bedifficult for motorists to see at crossings or stops.Determine if utility poles, vegetation, and otherroadside features interfere with the motorist’sability to see the children. When necessary,relocate the obstructions or move the bus stop.Parked vehicles can also block visibility andparking prohibitions might be necessary nearthe bus stop.

(7) Illumination and SigningIn Washington State, the highest number ofcollisions between vehicles and pedestrians occurin the months November through February whenthere is poor visibility and fewer daylight hours.At high pedestrian accident locations, illumina-tion of pedestrian crossings and other walkwaysis an important design consideration. Illuminationprovided solely for vehicular traffic is not alwayseffective in lighting parallel walkways forpedestrians. Consider additional lighting,mounted at a lower level, for walkways withconsiderable nighttime pedestrian activity.Design guidance for illumination is in Chapter840. See Chapter 820 and the MUTCD forpedestrian related signing.

1025.08 DocumentationPreserve the following documents in the projectfile: See Chapter 330.

� Decisions to prohibit pedestrians from astate highway.

� Decisions to prohibit a pedestrian crossingat an intersection.

� Approval of the installation of a midblockpedestrian crossing.

� Agreements with cities to install pedestriansidewalks or walkways along state high-ways within their jurisdiction.

� Approval of the installation of a bulb outon a state highway.

Pedestrian Design Considerations Design ManualPage 1025-10 Metric Version May 2001

Pedestrian WalkwaysFigure 1025-2a

1.8 m min.

Curb andgutter 2%

150 mm

0.3 m

Rounding

Embankment slopessteeper than 1:4

Sidewalk

0.6 m

150mm

Curb andgutter 2%

1.8 m min.0.3 m

0.9 m

2%

Embankment slopessteeper than 1:4

Rounding

min.Sidewalk

Case B

Case C

Buffer0.9 m min.

1.5 m min.Ped. Walkway

2%

Top soil if area isa planting strip See above cases for

slope treatment

Cement concrete orasphalt concrete

Curb andgutter

Case D

All "cut"slopes

1.8 m min. 0.3 m

2%

Embankment slopes1:4 or flatter

Curb andgutter

Sidewalk

Case A

Design Manual Pedestrian Design ConsiderationsMay 2001 Metric Version Page 1025-11

Pedestrian WalkwaysFigure 1025-2b

1.5 m min.Ped. walkway

See Figure 1025-2afor slope treatment

Cement concrete orasphalt concrete

0.3 m

Not steeperthan 1:4

0.3 mmin.

See Chapter 640for ditch slope

2%

Biofiltration area

Case G

1.8 m min.

2%

Pedestrian railing

Sidewalk

Vertical wall

Curb andgutter

Case EWhen the wall is outside of the Design Clear Zone

1.8 m min.

2%

Sidewalk

Vertical wall

Curb andgutter

Traffic barrier

Case FWhen the wall is within the Design Clear Zone

Bridge (Ped)railing

Slopes 1:2or steeper

Not steeperthan ± 2%

Traffic barrier

1.8 m min.

Ped. walkway

See Chapter 710 forlateral clearance Pedestrian railing

0.6 m

Case H

Pedestrian Design Considerations Design ManualPage 1025-12 Metric Version May 2001

Sidewalk RecommendationsFigure 1025-3

Roadway classification & land use Sidewalk recommendations

Rural highways (less than one dwelling

unit per 0.4 hectare)

No sidewalk recommended. Shoulder

(1.2 meter minimum width) adequate.

Suburban highways (one or less dwelling

units per 0.4 hectare)

Sidewalk on one side desirable. 1.2

meter wide shoulders adequate.

Suburban highway (2 to 4 dwelling units

per 0.4 hectare)

Sidewalks on both sides of roadway

desirable. Sidewalk on one side

recommended.

Major arterial in residential areaSidewalks on both sides of roadway

recommended.

Collector or minor arterial in residential

area

Sidewalks on both sides of roadway

recommended.

Local street in residential area with less

than 1 dwelling unit per 0.4 hectare

Sidewalk on one side desirable. 1.2

meter wide shoulders adequate.

Local street in residential area with 1 to 4

dwelling units per 0.4 hectare

Sidewalks on both sides of roadway

desirable. Sidewalk on one side

recommended.

Local street in residential area with more

than 4 dwelling units per 0.4 hectare

Sidewalks on both sides of roadway

recommended.

Streets in commercial areaSidewalks on both sides of roadway

recommended

Streets in industrial area

Sidewalks on both sides of roadway

desirable. Sidewalk on one side

recommended.

Design Manual Pedestrian Design ConsiderationsMay 2001 Metric Version Page 1025-13

Marked Crosswalk Recommendations at Unsignalized Pedestrian CrossingsFigure 1025-4

Roadway Type

Traffic

Volume

ADT

Speed Two Lane Three Lane

Multilane (4 or

more lanes)

with raised

median

Multilane (4 or

more lanes)

without raised

median

Less 30 mph or lessmarked

crosswalk

marked

crosswalk

marked

crosswalk

marked

crosswalk

Than 35 mphmarked

crosswalk

marked

crosswalk

marked

crosswalk

marked

crosswalk

9,00040 mph or

higher

marked

crosswalk

marked

crosswalk

marked

crosswalk

marked

crosswalk

9,000 30 mph or lessmarked

crosswalk

marked

crosswalk

marked

crosswalk

marked

crosswalk

to 35 mphmarked

crosswalk

marked

crosswalk

marked

crosswalk

additional

enhancement

11,99940 mph or

higher

marked

crosswalk

marked

crosswalk

marked

crosswalk

additional

enhancement

12,000 30 mph or lessmarked

crosswalk

marked

crosswalk

additional

enhancement

additional

enhancement

to 35 mphmarked

crosswalk

additional

enhancement

additional

enhancement

not

recommended

14,99940 mph or

higher

additional

enhancement

not

recommended

not

recommended

not

recommended

More 30 mph or lessmarked

crosswalk

additional

enhancement

additional

enhancement

not

recommended

than 35 mphadditional

enhancement

not

recommended

not

recommended

not

recommended

15,00040 mph or

higher

additional

enhancement

not

recommended

not

recommended

not

recommended

Notes:

These guidelines include intersection and midblock location with no traffic control

signals or stop signs on the approach to the crossing. They do not apply to school

crossings. A two-way left-turn lane is not considered a median. This chart is used in

conjunction with an engineering study of pedestrian volumes, model vehicle operating

speeds, sight distance, vehicle mix, and comparison to similar sites.

Meaning of terms in chart:

Marked crosswalk: Marked crosswalk can be installed at these locations.

Additional enhancements: Marked crosswalks can be used with additional safety

items such as overhead illumination, curb bulb outs, flashing beacons, illuminated

signing, or an in-roadway flashing light system.

Not recommended: A marked crosswalk is not recommended under these conditions

without positive vehicular traffic control such as stop signs or traffic control signals.

Pedestrian Design Considerations Design ManualPage 1025-14 Metric Version May 2001

Crosswalk LocationsFigure 1025-5

3 m

Typical

Unmarkedcrosswalkareas

Unmarked Crosswalks

at 4-Legged Intersection

Sidewalk ramp

3 m

Typical

Unmarkedcrosswalkareas

Unmarked Crosswalks

at Tee Intersection

Sidewalk ramp

Markedcrosswalks

Marked Crosswalks

at 4-Legged Intersection

Sidewalkramps

Marked Crosswalks

at Intersection with Refuge Island

RefugeIsland

Markedcrosswalks

Markedcrosswalks

Sidewalk ramp

Design Manual Pedestrian Design ConsiderationsMay 2001 Metric Version Page 1025-15

Sight Distance at IntersectionsFigure 1025-6a

Pedestrian waiting

to cross streetCrosswalk

Right turning

vehicle

Driver's line

of sight

Shrubbery blocking

driver's line of sight

Parked cars

Conventional right turn

curb radius

Parked car obstructs

line of sight

Driver's line of

sight

Pedestrian waiting to

cross street

Crosswalk

Approaching

vehicle

Shrubbery blocking line of sight

Parked car blocking line of sight

Stopping sight distance

Pedestrian Design Considerations Design ManualPage 1025-16 Metric Version May 2001

Sight Distance at IntersectionsFigure 1025-6b

Pedestrian waiting to

cross street

Bulb out right turn curb

radius

Parked cars

Eliminated

parking stall

Crosswalk

Curb Extension

Driver's line of

sight

Approaching

vehicle

CrosswalkDriver's line of

sight

Approaching

vehicle

Parked cars Pedestrian waiting to

cross street

Bulb out right turn

curb radius

Improved line of sight with curb bulb out

Improved line of sight with curb extension

Stopping sight distance

Stopping sight distance

Design Manual Pedestrian Design ConsiderationsMay 2001 Metric Version Page 1025-17

Sidewalk Bulb OutsFigure 1025-7

Pedestrian Design Considerations Design ManualPage 1025-18 Metric Version May 2001

Midblock Pedestrian CrossingFigure 1025-8

Design Manual Pedestrian Design ConsiderationsMay 2001 Metric Version Page 1025-19

Sidwalk Ramp DrainageFigure 1025-9

Sidewalk

ramps

Sidewalk

ramps

Flow direction

of surface

runoff

Flow direction

of surface

runoff

Drainage feature

(catch basin or

inlet)

Drainage feature

(catch basin or

inlet)

1130 Retaining Walls and Steep Reinforced Slopes

• Traffic characteristics

• Constructibility

• Impact to any adjacent environmentallysensitive areas

• Impact to adjacent structures

• Potential added lanes

• Length and height of wall

• Material to be retained

• Foundation support and potential fordifferential settlement

• Ground water

• Earthquake loads

• Right of way costs

• Need for construction easements

• Risk

• Overall cost

• Visual appearance

If the wall or toe of a reinforced slope is to belocated adjacent to the right of way line, considerthe space needed in front of the wall/slope toconstruct it.

(1) Retaining Wall ClassificationsRetaining walls are generally classified asgravity, semigravity, nongravity cantilever, oranchored. Examples of the various types of wallsare provided in Figures 1130-1a through 1c.

Gravity walls derive their capacity to resistlateral soil loads through a combination of deadweight and sliding resistance. Gravity wallscan be further subdivided into rigid gravitywalls, prefabricated modular gravity walls,and Mechanically Stabilized Earth (MSE)gravity walls.

Rigid gravity walls consist of a solid mass ofconcrete or mortared rubble and use the weightof the wall itself to resist lateral loads.

1130.01 References1130.02 General1130.03 Design Principles1130.04 Design Requirements1130.05 Guidelines for Wall/Slope Selection1130.06 Design Responsibility and Process1130.07 Documentation

113.01 ReferencesBridge Design Manual, M 23-50, WSDOT

Standard Plans for Road, Bridge, and MunicipalConstruction (Standard Plans), M 21-01,WSDOT

Plans Preparation Manual, M 22-31, WSDOT

Roadside Manual, M 25-39, WSDOT

1130.02 GeneralThe function of a retaining wall is to form anearly vertical face through confinement and/orstrengthening of a mass of earth or other bulkmaterial. Likewise, the function of a reinforcedslope is to strengthen the mass of earth or otherbulk material such that a steep (up to 2V:1H)slope can be formed. In both cases, the purpose ofconstructing such structures is to make maximumuse of limited right of way. The differencebetween the two is that a wall uses a structuralfacing whereas a steep reinforced slope does notrequire a structural facing. Reinforced slopestypically use a permanent erosion control mattingwith low vegetation as a slope cover to preventerosion. See the Roadside Manual for moreinformation.

To lay out and design a retaining wall orreinforced slope, consider the following items:

• Functional classification

• Highway geometry

• Design Clear Zone requirements(Chapter 700)

• The amount of excavation required

Design Manual Retaining Walls and Steep Reinforced SlopesNovember 1999 Metric Version Page 1130-1

Prefabricated modular gravity walls consist ofinterlocking soil or rock filled concrete, steel, orwire modules or bins (gabions, for example). Thecombined weight of these modules or bins resistthe lateral loads from the soil.

MSE gravity walls use strips, bars, or mats ofsteel or polymeric reinforcement to reinforce thesoil and create a reinforced soil block behind theface. The reinforced soil block then acts as a unitand resists the lateral soil loads through the deadweight of the reinforced mass. MSE walls maybe constructed as fill walls, with fill and rein-forcement placed in alternate layers to create areinforced mass, or reinforcement may be drilledinto an existing soil/rock mass using groutedanchor technology to create a reinforced soilmass (soil nail walls).

Semigravity walls rely more on structural resis-tance through cantilevering action of the wallstem. Generally, the backfill for a semigravitywall rests on part of the wall footing. The back-fill, in combination with the weight of the walland footing, provides the dead weight for resis-tance. An example of a semigravity wall isthe reinforced concrete wall provided in theStandard Plans.

Nongravity cantilever walls rely strictly on thestructural resistance of the wall in which verticalelements of the wall are partially embedded inthe soil or rock to provide fixity. These verticalelements may consist of piles (soldier piles orsheet piles, for example), caissons, or drilledshafts. The vertical elements may form the entirewall face or they may be spanned structurallyusing timber lagging or other materials to formthe wall face.

Anchored walls derive their lateral capacitythrough anchors embedded in stable soil or rockbelow or behind all potential soil/rock failuresurfaces. Anchored walls are similar to non-gravity cantilevered walls except that anchorsembedded in the soil/rock are attached to thewall facing structure to provide lateral resistance.Anchors typically consist of deadmen or groutedsoil/rock anchors.

Reinforced slopes are similar to MSE walls inthat they also use fill and reinforcement placed inalternate layers to create a reinforced soil mass.However, the face is typically built at a 1V:1.2Hto 2V:1H slope.

Rockeries (rock walls) behave to some extent likegravity walls. However, the primary function of arockery is to prevent erosion of an oversteepenedbut technically stable slope. Rockeries consist oflarge well-fitted rocks stacked on top of oneanother to form a wall.

An example of a rockery and reinforced slope isprovided in Figure 1130-1d. The various walltypes and their classifications are summarized inTable 1(a-f).

1130.03 Design PrinciplesThe design of a retaining wall or reinforced slopeconsists of seven principal activities:

• Developing wall/slope geometry

• Adequate subsurface investigation

• Evaluation of loads and pressures that willact on the structure

• Design of the structure to safely withstandthe loads and pressures

• Design of the structure to meet aestheticrequirements

• Wall/slope constructibility

• Coordination with other design elements

The structure and adjacent soil mass must alsobe stable as a system, and the anticipated wallsettlement must be within acceptable limits.

1130.04 Design Requirements(1) Wall/Slope GeometryWall/slope geometry is developed consideringthe following:

• Geometry of the transportation facility itself

• Design Clear Zone requirements (Chapter700)

• Flare rate and approach slope when inside theDesign Clear Zone (Chapter 710)

Retaining Walls and Steep Reinforced Slopes Design ManualPage 1130-2 Metric Version December 1998

• Right of way constraints

• Existing ground contours

• Existing and future utility locations

• Impact to adjacent structures

• Impact to environmentally sensitive areas

• For wall/slope geometry, also consider thefoundation embedment and type anticipated,which requires coordination among thevarious design groups involved.

Retaining walls must not have anything (such asbridge columns, light fixtures, or sign supports)protruding in such a way as to present a potentialfor snagging vehicles.

Provide a traffic barrier shape at the base of anew retaining wall constructed 3.6 m or less fromthe edge of the nearest traffic lane. The trafficbarrier shape is optional at the base of the newportion when an existing vertical-faced wall isbeing extended (or the existing wall may beretrofitted for continuity). Standard ConcreteBarrier Type 4 is recommended for both new andexisting walls except when the barrier face can becast as an integral part of a new wall. Deviationsmay be considered but require approval asprescribed in Chapter 330. For deviations fromthe above, deviation approval is not requiredwhere sidewalk exists in front of the wall or inother situations where the wall face is otherwiseinaccessible to traffic.

(2) Investigation of SoilsAll retaining wall and reinforced slope structuresrequire an investigation of the underlyingsoil/rock that supports the structure. Chapter 510provides guidance on how to complete thisinvestigation. A soil investigation is critical forthe design of any retaining wall or reinforcedslope. The stability of the underlying soils, theirpotential to settle under the imposed loads, theusability of any existing excavated soils forwall/reinforced slope backfill, and the locationof the ground water table are determined throughthe geotechnical investigation.

(3) Geotechnical and StructuralDesignThe structural elements of the wall or slope andthe soil below, behind, and/or within the structuremust be designed together as a system. Thewall/slope system is designed for overall externalstability as well as internal stability. Overallexternal stability includes stability of the slopeof which the wall/reinforced slope is a part andthe local external stability (overturning, sliding,and bearing capacity). Internal stability includesresistance of the structural members to load and,in the case of MSE walls and reinforced slopes,pullout capacity of the structural members or soilreinforcement from the soil.

(4) Drainage DesignOne of the principal causes of retainingwall/slope failure is the additional hydrostaticload imposed by an increase in the water contentin the material behind the wall or slope. Thiscondition results in a substantial increase in thelateral loads behind the wall/slope since thematerial undergoes a possible increase in unitweight, water pressure is exerted on the back ofthe wall, and the soil shear strength undergoes apossible reduction. To alleviate this, adequatedrainage for the retaining wall/slope must beconsidered in the design stage and reviewed bythe Region Materials Engineer during construc-tion. The drainage features shown in the StandardPlans are the minimum basic requirements.Underdrains behind the wall/slope must daylightat some point in order to adequately perform theirdrainage function. Provide positive drainage atperiodic intervals to prevent entrapment of water.

Native soil may be used for retaining wall andreinforced slopes backfill if it meets the require-ments for the particular wall/slope system. Ingeneral, use backfill that is free-draining andgranular in nature. Exceptions to this can be madedepending on the site conditions as determined bythe Geotechnical Services Branch of the OlympiaService Center (OSC) Materials Laboratory.

Design Manual Retaining Walls and Steep Reinforced SlopesDecember 1998 Metric Version Page 1130-3

A typical drainage detail for a gravity wall (inparticular, an MSE wall) is shown in Figure1130-2. Typical drainage details for a standardreinforced concrete cantilever wall are providedin the DETAILS.CEL library. Always includedrainage details such as these with a wall unlessotherwise recommended to be deleted by theregion’s Materials Engineer or OSC GeotechnicalServices Branch.

(5) AestheticsRetaining walls and slopes should have a pleasingappearance that is compatible with the surround-ing terrain and other structures in the vicinity. Tothe extent possible within functional requirementsand cost effectiveness criteria, this aesthetic goalshould be met for all visible retaining walls andreinforced slopes.

Aesthetic requirements include consideration ofthe wall face material, the top profile, the termi-nals, and the surface finish (texture, color, andpattern). Where appropriate, provide plantingareas and irrigation conduits. These will visuallysoften them and blend the them with adjacentareas. Avoid short sections of retaining wall orsteep slope where possible.

In higher walls, variations in slope treatment arerecommended for a pleasing appearance. High,continuous walls are generally not desirable froman aesthetic standpoint, as high, continuous wallscan be quite imposing. Consider stepping high orlong retaining walls in areas of high visibility.Plantings could be considered between wall steps.

Approval from the Principle Architect of theBridge and Structures Office is required on allretaining wall aesthetics including finishes.

(6) ConstructibilityConsider the potential effect site constraintsmay have on the constructibility of the specificwall/slope. Constraints to be considered include,but are not limited to, site geometry, access, timerequired to construct the wall, environmentalissues, and impact on traffic flow and otherconstruction activities.

(7) Coordination with Other DesignElements(a) Other Design Elements. Retaining wall andslope designs must be coordinated with otherelements of the project that could interfere withor impact the design and/or construction of thewall/slope. Also consider drainage features,utilities, luminaire or sign structures, adjacentretaining walls or bridges, concrete traffic barri-ers, and beam guardrails. Locate these designelements in a manner that will minimize theimpacts to the wall elements. In general, locateobstructions within the wall backfill (such asguardrail posts, drainage features, and minorstructure foundations) a minimum of 1 m fromthe back of the wall facing units. Greater offsetdistances may be required depending on the sizeand nature of the interfering design element. Ifpossible, locate these elements to miss reinforce-ment layers or other portions of the wall system.Conceptual details for accommodating concretetraffic barriers and beam guardrails are providedin Figure 1130-3.

Where impact to the wall elements is unavoid-able, the wall system must be designed toaccommodate these impacts. For example, itmay be necessary to place drainage structures orguardrail posts in the reinforced backfill zone ofMSE walls. This may require that holes be cutin the upper soil reinforcement layers, or thatdiscrete reinforcement strips be splayed aroundthe obstruction. This causes additional load to becarried in the adjacent reinforcement layers dueto the missing soil reinforcement or the distortionin the reinforcement layers.

The need for these other design elements andtheir impact on the proposed wall systems mustbe clearly indicated in the wall site data that issubmitted so that the walls can be properlydesigned. Contact the Bridge and StructuresOffice (or the Geotechnical Services Branch,for geosynthetic walls/slopes and soil nailwalls) for assistance regarding this issue.

Retaining Walls and Steep Reinforced Slopes Design ManualPage 1130-4 Metric Version May 2001

(b) Fall Protection. Department of Labor andIndustries regulations require that, when employ-ees are exposed to the possibility of falling froma location 3 m or more above the roadway (orother lower area), the employer is to ensure thatfall restraint or fall arrest systems are provided,installed, and implemented.

Consider fall protection when a wall retains 3 mor more of material. Any need for maintenanceof the wall’s surface or the area at the top canexpose employees to a possible fall. If the areaat the top will be open to the public, see Chapter1025, “Pedestrian Design Considerations,” andChapter 1460, “Fencing.”

For maintenance of a tall wall’s surface, considerharness tie-offs if other protective means arenot provided.

For maintenance of the area at the top of a tallwall, a fall restraint system is required when allof the following conditions will exist:

• The wall is on a cut slope.

• A possible fall would be of 3 m or more.

• Periodic maintenance will be performed onthe area at the top.

• The area at the top is not open to the public.

Recommended fall restraint systems are:

• Wire rope railing with top and intermediaterails of one-half inch diameter steel wirerope.

• Brown vinyl coated chain link fencing.

• Steel pipe railing with one and one-half inchnominal outside diameter pipe as posts andtop and intermediate rails.

• Concrete as an extension of the height of theretaining wall.

A fall restraint system must be 91 mm to 106 mmhigh, measured from the top of the finished grade,and capable of withstanding a 90 kg force fromany direction, at the top, with minimal deflection.Post spacing is no more than 2.5 m on centers.

During rail system selection, the designer is tocontact Maintenance regarding debris removalconsiderations.

Contact the Bridge and Structures Office fordesign details for any retrofit to an existingretaining wall and for any attachments to anew retaining wall.

1130.05 Guidelines for Wall/SlopeSelectionWall/slope selection is dependent on thefollowing considerations:

• Whether the wall/slope will be locatedprimarily in a cut or fill (how much excava-tion/shoring will be required to construct thewall or slope?)

• If located in a cut, the type of soil/rockpresent

• The need for space between the right of wayline and the wall/slope or easement

• The amount of settlement expected

• The potential for deep failure surfaces tobe present

• The structural capacity of the wall/slope interms of maximum allowable height

• The nature of the wall/slope application

• Whether or not structures or utilities will belocated on or above the wall

• Architectural requirements

• Overall economy

(1) Cut and Fill ConsiderationsDue to the construction technique and base widthrequired, some wall types are best suited for cutsituations whereas others are best suited for fillsituations. For example, anchored walls and soilnail walls have soil reinforcements drilled intothe in-situ soil/rock and, therefore, are generallyused in cut situations. Nongravity cantileveredwalls are drilled or cut into the in-situ soil/rock,have narrow base widths, and are also well suitedto cut situations. Both types of walls are con-structed from the top down. Such walls are alsoused as temporary shoring to allow other typesof walls or other structures to be constructedwhere considerable excavation would otherwisebe required.

Design Manual Retaining Walls and Steep Reinforced SlopesMay 2001 Metric Version Page 1130-5

MSE walls and reinforced slopes, however, areconstructed by placing soil reinforcement be-tween layers of fill from the bottom up and aretherefore best suited to fill situations. Further-more, the base width of MSE walls is typicallyon the order of 70 percent of the wall height,which would require considerable excavation ina cut situation. Therefore, in a cut situation, basewidth requirements usually make MSE structuresuneconomical and possibly unconstructible.

Semigravity (cantilever) walls, rigid gravitywalls, and prefabricated modular gravity wallsare free-standing structural systems built from thebottom up but they do not rely on soil reinforce-ment techniques (placement of fill layers withsoil reinforcement) to provide stability. Thesetypes of walls generally have a narrower basewidth than MSE structures, (on the order of50 percent of the wall height). Both of thesefactors make these types of walls feasible infill situations as well as many cut situations.

Reinforced slopes generally require more roomoverall to construct than a wall because of thesloping face, but are typically a feasible alterna-tive to a combination wall and fill slope to add anew lane. Reinforced slopes can also be adaptedto the existing ground contours to minimizeexcavation requirements where fill is placed onan existing slope. Reinforced slopes may also befeasible to repair slopes damaged by landslideactivity or deep erosion.

Rockeries are best suited to cut situations, as theyrequire only a narrow base width, on the order of30 percent of the rockery height. Rockeries canbe used in fill situations, but the fill heights thatthey support must be kept relatively low as it isdifficult to get the cohesive strength needed ingranular fill soils to provide minimal stabilityof the soil behind the rockery at the steep slopetypically used for rockeries in a cut (such as6V:1H or 4V:1H).

The key considerations in deciding which wallsor slopes are feasible are the amount of excava-tion or shoring required and the overall height.The site geometric constraints must be welldefined to determine these elements. Anotherconsideration is whether or not an easement will

be required. For example, a temporary easementmay be required for a wall in a fill situation toallow the contractor to work in front of the wall.For walls in cut situations, especially anchoredwalls and soil nail walls, a permanent easementmay be required for the anchors or nails.

(2) Settlement and Deep FoundationSupport ConsiderationsSettlement issues, especially differential settle-ment, are of primary concern for selection ofwalls. Some wall types are inherently flexibleand can tolerate a great deal of settlement with-out suffering structurally. Other wall types areinherently rigid and cannot tolerate much settle-ment. In general, MSE walls have the greatestflexibility and tolerance to settlement, followedby prefabricated modular gravity walls. Rein-forced slopes are also inherently very flexible.For MSE walls, the facing type used can affectthe ability of the wall to tolerate settlement.Welded wire and geosynthetic wall facings arethe most flexible and the most tolerant to settle-ment, whereas concrete facings are less tolerantto settlement. In some cases, concrete facing canbe placed, after the wall settlement is complete,such that the concrete facing does not limit thewall’s tolerance to settlement. Facing may alsobe added for aesthetic reasons.

Semigravity (cantilever) walls and rigid gravitywalls have the least tolerance to settlement. Ingeneral, total settlement for these types of wallsmust be limited to approximately 25 mm or less.Rockeries also cannot tolerate much settlement,as rocks could shift and fall out. Therefore,semigravity cantilever walls, rigid gravitywalls, and rockeries are not used in settlementprone areas.

If very weak soils are present that will notsupport the wall and that are too deep to beoverexcavated, or if a deep failure surface ispresent that results in inadequate slope stability,the wall type selected must be capable of usingdeep foundation support and/or anchors. Ingeneral, MSE walls, prefabricated modulargravity walls, and some rigid gravity wallsare not appropriate for these situations. Wallsthat can be pile supported such as concrete

Retaining Walls and Steep Reinforced Slopes Design ManualPage 1130-6 Metric Version May 2001

semigravity cantilever walls, nongravitycantilever walls, and anchored walls are moreappropriate for these situations.

(3) Feasible Wall and Slope Heightsand ApplicationsFeasible wall heights are affected by issues suchas the capacity of the wall structural elements,past experience with a particular wall, currentpractice, seismic risk, long-term durability,and aesthetics.

See Table 1 for height limitations.

(4) Supporting Structures or UtilitiesNot all walls are acceptable to support otherstructures or utilities. Issues that must be consid-ered include the potential for the wall to deformdue to the structure foundation load, interferencebetween the structure foundation and the wallcomponents, and the potential long-term durabil-ity of the wall system. Using retaining walls tosupport other structures is considered to be acritical application, requiring a special design.In general, soil nail walls, semigravity cantileverwalls, nongravity cantilever walls, and anchoredwalls are appropriate for use in supporting bridgeand building structure foundations. In additionto these walls, MSE and prefabricated modulargravity walls may be used to support otherretaining walls, noise walls, and minor structurefoundations such as those for sign bridges andsignals. On a project specific basis, MSE wallscan be used to support bridge and buildingfoundations, as approved by the Bridge andStructures Office.

Also consider the location of any utilities behindthe wall or reinforced slope when makingwall/slope selections. This is mainly an issue forwalls that use some type of soil reinforcementand for reinforced slopes. It is best not to placeutilities within a reinforced soil backfill zonebecause it would be impossible to access theutility from the ground surface without cuttingthrough the soil reinforcement layers, therebycompromising the integrity of the wall.

Sometimes utilities, culverts, pipe arches, etc.must penetrate the face of a wall. Not all wallsand facings are compatible with such penetra-

tions. Consider how the facing can be formedaround the penetration so that backfill soilcannot pipe or erode through the face. Contactthe Bridge and Structures Office for assistanceregarding this issue.

(5) Facing OptionsFacing selection depends on the aesthetic and thestructural needs of the wall system. Wall settle-ment may also affect the feasibility of the facingoptions. More than one wall facing may beavailable for a given system. The facing optionsavailable must be considered when selecting aparticular wall.

For MSE walls, facing options typically includethe following:

• Precast modular panels

• In some cases, full height precast concretepanels. (Full height panels are generallylimited to walls with a maximum height of6 m placed in areas where minimal settlementis expected.)

• Welded wire facing

• Timber facing

• Shotcrete facing with various treatmentoptions that vary from a simple broom finishto a textured and colored finish

• Segmental masonry concrete blocks

• Cast-in-place concrete facing with varioustexturing options.

Plantings on welded wire facings can beattempted in certain cases. The difficulty is inproviding a soil at the wall face that is suitablefor growing plants and meets engineeringrequirements in terms of soil compressibility,strength, and drainage. If plantings in the wallface are attempted, use only small plants, vines,and grasses. Small bushes could be consideredfor plantings between wall steps. Larger bushesor trees are not considered in these cases due tothe loads on the wall face that they can create.

Geosynthetic facings are not acceptable forpermanent facings due to potential facing degra-dation when exposed to sunlight. For permanentapplications, geosynthetic walls must have some

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type of timber, welded wire, or concrete face.(Shotcrete, masonry concrete blocks, cast-in-place concrete, welded wire, or timber aretypically used for geosynthetic wall facings.)

Soil nail walls can use either architecturallytreated shotcrete or a cast-in-place facia walltextured as needed to produce the desiredappearance.

For prefabricated modular gravity walls, thefacing generally consists of the structural binor crib elements used to construct the walls. Forsome walls, the elements can be rearranged toform areas for plantings. In some cases, texturedstructural elements may also be feasible. This isalso true of rigid gravity walls, though plantingareas on the face of rigid gravity walls aregenerally not feasible. The concrete facing forsemigravity cantilever walls can be textured asneeded to produce the desired appearance.

For nongravity cantilevered walls and anchoredwalls, a textured cast-in-place or precast faciawall is usually installed to produce the desiredappearance.

(6) Cost ConsiderationsUsually, more than one wall type is feasible fora given situation. Consider cost throughout theselection process. Decisions in the selectionprocess that may affect the overall cost mightinclude the problem of whether to shut down alane of traffic to install a low cost gravity wallsystem that requires more excavation room or touse a more expensive anchored wall system thatwould minimize excavation requirements andimpacts to traffic. In this case, determine if thecost of traffic impacts and more excavationjustifies the cost of the more expensiveanchored wall system.

Decisions regarding aesthetics can also affect theoverall cost of the wall system. In general, theleast expensive aesthetic options use the struc-tural members of the wall as facing (welded wire,concrete or steel cribbing or bins, for example),whereas the most expensive aesthetic options usetextured cast-in-place concrete facias. In general,concrete facings increase in cost in the following

order: shotcrete, segmental masonry concreteblocks, precast concrete facing panels, full heightprecast concrete facing panels, and cast-in-placeconcrete facing panels. Special architecturaltreatment usually increases the cost of any ofthese facing systems. Special wall terracing toprovide locations for plants will also tend toincrease costs. Therefore, the value of the desiredaesthetics must be weighed against costs.

Other factors that affect costs of wall/slopesystems include wall/slope size and length, accessat the site and distance to the material supplierlocation, overall size of the project, and competi-tion between wall suppliers. In general, costs tendto be higher for walls or slopes that are high, butshort in length, due to lack of room for equipmentto work. Sites that are remote or have difficultlocal access increase wall/slope costs. Smallwall/slope quantities result in high unit costs.Lack of competition between materials or wallsystem suppliers can result in higher costs aswell.

Some of the factors that increase costs arerequired parts of a project and are, therefore,unavoidable. Always consider such factors whenestimating costs because a requirement may notaffect all wall types in the same way. Currentcost information can be obtained by consultingthe Bridge Design Manual or by contacting theBridge and Structures Office.

(7) SummaryFor wall/slope selection, consider factors such asthe intended application, the soil/rock conditionsin terms of settlement, need for deep foundations,constructibility, impact to traffic, the overallgeometry in terms of wall/slope height andlength, location of adjacent structures andutilities, aesthetics, and cost. Table 1 providesa summary of many of the various wall/slopeoptions available, including their advantages,disadvantages, and limitations. Note that specificwall types in the table may represent multiplewall systems, some or all of which may beproprietary.

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1130.06 Design Responsibility andProcess(1) GeneralThe retaining walls available for a given projectinclude standard walls, nonstandard walls, andreinforced slopes.

Standard walls are those walls for which standarddesigns are provided in the WSDOT StandardPlans. Standard plans are provided for reinforcedconcrete cantilever walls up to 11 m in height.The internal stability design, and the externalstability design for overturning and slidingstability, have already been completed for thesestandard walls. However, overall slope stabilityand allowable soil bearing capacity (includingsettlement considerations) must be determinedfor each standard-design wall location.

Nonstandard walls may be either proprietary(patented or trademarked) or nonproprietary.Proprietary walls are designed by a wall manu-facturer for internal and external stability, exceptbearing capacity, settlement, and overall slopestability which are determined by WSDOT.Nonstandard nonproprietary walls are fullydesigned by WSDOT.

The geosynthetic soil reinforcement used innonstandard nonproprietary geosynthetic wallsis considered to be proprietary. It is likely thatmore than one manufacturer can supply propri-etary materials for a nonstandard nonproprietarygeosynthetic wall.

Reinforced slopes are similar to nonstandardnonproprietary walls in terms of their designprocess.

Some proprietary wall systems are preapproved.Preapproved proprietary wall systems have beenextensively reviewed by the Bridge and Struc-tures Office and the Geotechnical ServicesBranch. Design procedures and wall details forpreapproved walls have already been agreedupon between WSDOT and the proprietary wallmanufacturers, allowing the manufacturers tocompetitively bid a particular project withouthaving a detailed wall design provided in thecontract plans.

Note that proprietary wall manufacturers mayproduce several retaining wall options, and not alloptions from a given manufacturer have necessar-ily been preapproved. For example, proprietarywall manufacturers often offer more than onefacing alternative. It is possible that some facingalternatives are preapproved, whereas otherfacing alternatives are not preapproved. WSDOTdoes not preapprove the manufacturer, butspecific wall systems by a given manufacturercan be preapproved.

It is imperative with preapproved systems that thedesign requirements for all preapproved wallalternatives for a given project be clearly statedso that the wall proprietor can adapt thepreapproved system to specific project condi-tions. For a given project, coordination of thedesign of all wall alternatives with all projectelements that impact the wall (such as drainagefeatures, utilities, luminaires and sign structures,noise walls, traffic barriers, guardrails, or otherwalls or bridges) is critical to avoid costly changeorders or delays during construction.

In general, standard walls are the easiest wallsto incorporate into project plans, specifications,& estimate (PS&E), but they may not be themost cost effective option. Preapproved propri-etary walls provide more options in terms ofcost effectiveness and aesthetics and are alsorelatively easy to incorporate into a PS&E.Nonstandard state-designed walls and nonpre-approved proprietary walls generally take moretime and effort to incorporate into a PS&Ebecause a complete wall design must be devel-oped. Some nonstandard walls (state-designedgeosynthetic walls, for example) can be designedrelatively quickly, require minimal plan prepara-tion effort, and only involve the region and theGeotechnical Services Branch. Other nonstandardwalls such as soil nail and anchored wall systemsrequire complex designs, involve both the Bridgeand Structures Office and the GeotechnicalServices Branch, and require a significant numberof plan sheets and considerable design effort.

The Bridge and Structures Office maintains alist of the proprietary retaining walls that arepreapproved. The region should consult the

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Bridge and Structures Office for the latest list.The region should consult the GeotechnicalServices Branch for the latest geosyntheticreinforcement list to determine whichgeosynthetic products are acceptable if a criticalgeosynthetic wall or reinforced slope applicationis anticipated.

Some proprietary retaining wall systems areclassified as experimental by the FHWA. TheBridge and Structures Office maintains a list ofwalls that are classified as experimental. If thewall intended for use is classified as experimen-tal, a work plan must be prepared by WSDOTand approved by the FHWA.

Gabion walls are nonstandard walls that must bedesigned for overturning, sliding, overall slopestability, settlement, and bearing capacity. A fulldesign for gabion walls is not provided in theStandard Plans. Gabion baskets are typically0.9 m high by 0.9 m wide, and it is typically safeto build gabions two baskets high (1.8 m) butonly one basket deep, resulting in a wall basewidth of 50 percent of the wall height, providedsoil conditions are reasonably good (mediumdense to dense granular soils are present belowand behind the wall).

(2) Responsibility and Processfor DesignA flow chart illustrating the process and responsi-bility for retaining wall/reinforced slope designis provided in Figure 1130-4. As shown in thefigure, the region initiates the process, exceptfor walls developed as part of a preliminarybridge plan. These are initiated by the Bridgeand Structures Office. In general, it is the respon-sibility of the design office initiating the designprocess to coordinate with other groups in thedepartment to identify all wall/slope systemsthat are appropriate for the project in question.Coordination between the region, Bridge andStructures Office, Geotechnical Services Branch,and the Principle Architect should occur as earlyin the process as possible.

OSC or region consultants, if used, are consid-ered an extension of the OSC staff and mustfollow the process summarized in Figure 1130-4.All consultant designs, from development of

the scope of work to the final product, must bereviewed and approved by the appropriateOSC offices.

(a) Standard Walls. The regions are respon-sible for detailing retaining walls for whichstandard designs are available.

For standard walls greater than 3 m in height,and for all standard walls where soft or unstablesoil is present beneath or behind the wall, ageotechnical investigation must be conducted,or reviewed and approved, by the GeotechnicalServices Branch. Through this investigation,provide the foundation design including bearingcapacity requirements and settlement determin-ation, overall stability, and the selection of thewall types most feasible for the site.

For standard walls 3 m in height or less wheresoft or unstable soils are not present, it is theresponsibility of the region materials laboratoryto perform the geotechnical investigation. If ithas been verified that soil conditions are adequatefor the proposed standard wall that is less than orequal to 3 m in height, the region establishes thewall footing location based on the embedmentcriteria in the Bridge Design Manual, or placesthe bottom of the wall footing below any surficialloose soils. During this process, the region alsoevaluates other wall types that may be feasiblefor the site in question.

Figure 1130-5 provides design charts for standardreinforced concrete cantilever walls. Thesedesign charts, in combination with the StandardPlans, are used to size the walls and determinethe applied bearing stresses to compare with theallowable soil bearing capacity deter-mined fromthe geotechnical investigation. The charts providetwo sets of bearing pressures: one for static loads,and one for earthquake loads. Allowable soilbearing capacity for both the static load case andthe earthquake load case can be obtained fromthe Geotechnical Services Branch for standardwalls over 3 m in height and from the regionmaterials laboratories for standard walls less thanor equal to 3 m in height. If the allowable soilbearing capacity exceeds the values provided inFigure 1130-5, the Standard Plans can be used forthe wall design. If one or both of the allowablesoil bearing capacities does not exceed the values

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provided in Figure 1130-5, the Standard Planscannot be used for wall design and the Bridgeand Structures Office must be contacted for anonstandard wall design.

If the standard wall must support surchargeloads from bridge or building foundations, otherretaining walls, noise walls, or other types ofsurcharge loads, a special wall design is required.The wall is considered to be supporting thesurcharge load and is treated as a nonstandardwall if the surcharge load is located within a1V:1H slope projected up from the bottom ofthe back of the wall. Contact the Bridge andStructures Office for assistance

The Standard Plans provide six types of rein-forced concrete cantilever walls (which representsix loading cases). Reinforced concrete retainingwall Types 5 and 6 are not designed to withstandearthquake forces and are not used in WesternWashington (west of the Cascade crest).

Once the geotechnical and architectural assess-ment have been completed, the region completesthe PS&E for the standard wall option(s) selectedincluding a generalized wall profile and plan, atypical cross-section as appropriate, details fordesired wall appurte-nances, drainage details,and other details as needed.

Metal bin walls, Types 1 and 2, have been deletedfrom the Standard Plans and are there-fore nolonger standard walls. Metal bin walls are seldomused due to cost and undesirable aesthetics. If thistype of wall is proposed, contact the Bridge andStructures Office for plan details and toe bearingpressures. The applied toe bearing pressure wouldthen have to be evaluated by the GeotechnicalServices Branch to determine if the site soilconditions are appropriate for the applied loadand anticipated settlement.

(b) Preapproved Proprietary Walls. Finaldesign approval of preapproved proprietary walls,with the exception of geosynthetic walls, is theresponsibility of the Bridge and Structures Office.Final approval of the design of preapprovedproprietary geosynthetic walls is the responsibil-ity of the Geotechnical Services Branch. It is theregion’s responsibility to coordinate the designeffort for all preapproved wall systems.

The region materials laboratory performs thegeotechnical investigation for preapprovedproprietary walls 3 m in height or less that arenot bearing on soft or unstable soils. In allother cases, it is the responsibility of theGeotechnical Services Branch to conduct, orreview and approve, the geotechnical investiga-tion for the wall. The region also coordinates withthe Principal Architect to ensure that the walloptions selected meet the aesthetic requirementsfor the site.

Once the geotechnical and architectural assess-ments have been completed and the desired wallalternatives selected, it is the responsibility of theregion to contact the suppliers of the selectedpreapproved systems to confirm in writing theadequacy and availability of the systems for theproposed use.

A minimum of three different wall systems mustbe included in the PS&E for any project withfederal participation that includes a proprietarywall system unless specific justification isprovided. Standard walls can be alternatives.

Once confirmation of adequacy and availabilityhas been received, the region contacts the Bridgeand Structures Office for special provisions forthe selected wall systems and proceeds to finalizethe contract PS&E in accordance with the PlansPreparation Manual. Provide the allowablebearing capacity and foundation embedmentcriteria for the wall, as well as backfill andfoundation soil properties, in the special provi-sions. In general, assume that Gravel Borrow orbetter quality backfill material will be used forthe walls when assessing soil parameters.

Complete wall plans and designs for the propri-etary wall options will not be developed untilafter the contract is awarded, but will be devel-oped by the proprietary wall supplier as shopdrawings after the contract is awarded. Therefore,include a general wall plan, a profile showingneat line top and bottom of the wall, a finalground line in front of and in back of the wall, atypical cross-section, and the generic details forthe desired appurtenances and drainage require-ments in the contract PS&E for the proprietarywalls. Estimate the ground line in back of thewall based on a nominal 0.5 m facing thickness

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(and state this on the wall plan sheets). Includeload or other design acceptance requirements forthese appurtenances in the PS&E. Contact theBridge and Structures Office for assistanceregarding this.

It is best to locate catch basins, grate inlets, signalfoundations, and the like outside the reinforcedbackfill zone of MSE walls to avoid interferencewith the soil reinforcement. In those cases whereconflict with these reinforcement obstructionscannot be avoided, the location(s) and dimensionsof the reinforcement obstruction(s) relative tothe wall must be clearly indicated on the plans.Contact the Bridge and Structures Office forpreapproved wall details and designs for size andlocation of obstructions, and to obtain the genericdetails that must be provided in the plans. If theobstruction is too large or too close to the wallface, a special design may be required to accom-modate the obstruction, and the wall is treated asa nonpreapproved proprietary wall.

A special design is required if the wall mustsupport structure foundations, other retainingwalls, noise walls, signs or sign bridges, lumi-naires, or other types of surcharge loads. The wallis considered to be supporting the surcharge loadif the surcharge is located within a 1V:1H slopeprojected from the bottom of the back of the wall.For MSE walls, the back of the wall is consideredto be the back of the soil reinforcement layers.If this situation occurs, the wall is treated as anonpreapproved proprietary wall.

For those alternative wall systems that have thesame face embedment criteria, the wall facequantities depicted in the plans for each alterna-tive must be identical. To provide an equal basisfor competition, the region determines wall facequantities based on neat lines.

Once the detailed wall plans and designs areavailable as shop drawings after contract award,the Bridge and Structures Office will review andapprove the wall shop drawings and calculations,with the exception of geosynthetic walls whichare reviewed and approved by the GeotechnicalServices Branch.

(c) Nonpreapproved Proprietary Walls. Finaldesign approval authority for nonpreapprovedproprietary walls is the same as for preapprovedproprietary walls. The region initiates the designeffort for all nonpreapproved wall systems bysubmitting wall plan, profile, cross-section, andother information for the proposed wall to theBridge and Structures Office, with copies to theGeotechnical Services Branch and the PrincipalArchitect. The Bridge and Structures Officecoordinates the wall design effort.

Once the geotechnical and architectural assess-ments have been completed and the desired walltypes selected, the Bridge and Structures Officecontacts suppliers of the nonpreapproved wallsystems selected to obtain and review detailedwall designs and plans to be included in thecontract PS&E.

To ensure fair competition between all wallalternatives included in the PS&E, the wall facequantities for those wall systems subject to thesame face embedment requirements shouldbe identical.

The Bridge and Structures Office develops thespecial provisions and cost estimates for thenonpreapproved proprietary walls and sendsthe wall PS&E to the region for inclusion inthe final PS&E in accordance with the PlansPreparation Manual.

(d) Nonstandard Nonproprietary Walls.With the exception of rockeries over 1.5 m high,nonproprietary geosynthetic walls and reinforcedslopes, and soil nail walls, the Bridge and Struc-tures Office coordinates with the GeotechnicalServices Branch and the Principal Architect tocarry out the design of all nonstandard, non-proprietary walls. In this case, the Bridge andStructures Office develops the wall preliminaryplan from site data provided by the region,completes the wall design, and develops thenonstandard nonproprietary wall PS&E packagefor inclusion in the contract.

For rockeries over 1.5 m high, nonproprietarygeosynthetic walls and reinforced slopes, andsoil nail walls, the region develops wall/slopeprofiles, plans, and cross-sections and submitsthem to the Geotechnical Services Branch tocomplete a detailed wall/slope design.

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For geosynthetic walls and slopes, and forrockeries, the region provides overall coordina-tion of the wall/slope design effort, includingcoordination with the Principal Architect regard-ing aesthetics and finishes, and the Region orOSC Landscape Architect if the wall uses vege-tation on the face. The Geotechnical ServicesBranch has overall design approval authority.Once the wall design has been completed, theGeotechnical Services Branch, and in somecases the Bridge and Structures Office, providesgeotechnical and structural plan details to beincluded in the region plan sheets and specialprovisions for the PS&E. The regionthen completes the PS&E package.

For soil nail walls, once the GeotechnicalServices Branch has performed the geotechnicaldesign, the Bridge and Structures Office, incooperation with the Geotechnical ServicesBranch, coordinates the design effort andcompletes the PS&E package.

(3) Guidelines for Wall/Slope DataSubmission for Design(a) Standard Walls, Proprietary Walls,Geosynthetic Walls/Slopes, and Soil NailWalls. Where OSC involvement in retainingwall/slope design is required (as for standardwalls and preapproved proprietary walls over 3 min height, gabions over 2 m in height, rockeriesover 1.5 m in height, all nonpreapproved propri-etary walls, geosynthetic walls/slopes, and allsoil nail walls), the region submits the followinginformation to the Geotechnical Services Branchor Bridge and Structures Office as appropriate:

• Wall/slope plans.

• Profiles showing the existing and final gradesin front of and behind the wall.

• Wall/slope cross-sections (typically every15 m) or CAiCE files that define the existingand new ground-line above and below thewall/slope and show stations and offsets.

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• Location of right of way lines as well as otherconstraints to wall/slope construction.

• Location of adjacent existing and/or proposedstructures, utilities, and obstructions.

• Desired aesthetics.

• Date design must be completed.

• Key region contacts for the project.

Note that it is best to base existing groundmeasurements, for the purpose of defining thefinal wall geometry, on physical survey datarather than solely on photogrammetry. In addi-tion, the region must complete a RetainingWall/Reinforced Slope Site Data Check List,DOT Form 351-009 EF, for each wall or groupof walls submitted.

(b) Nonstandard Walls, Except GeosyntheticWalls/Slopes and Soil Nail Walls. In this case,the region must submit site data in accordancewith Chapter 1110. Additionally, a RetainingWall Site Data Check List, DOT361-009EF, foreach wall or group of walls must be completedby the region.

1130.07 DocumentationThe following documents are to be preserved inthe project file. See Chapter 330.

� Wall Site Data Check List,DOT361-009EF, and attachments

� Final selection approval

Table 1(a).Summary of mechanically stabilized earth (MSE) gravity wall/slope options available.

SpecificWall Type Advantages Disadvantages Limitations

Steel soilreinforcementwith full heightprecastconcrete panels

Relatively low cost Can tolerate littlesettlement; generallyrequires high qualitybackfill; wide basewidth required (70%of wall height)

Applicable primarily to fillsituations; maximum feasibleheight is approximately 6 m

Steel soilreinforcementwith modularprecast concretepanels

Relatively low cost;flexible enough tohandle significantsettlement

Generally requires highquality backfill; widebase width required(70% of wall height)

Applicable primarily to fillsituations; maximum height of10 m; heights over 10 m requirea special design

Steel soilreinforcementwith weldedwire and cast inplace concreteface

Can tolerate largeshort-termsettlements

Relatively high cost;cannot tolerate long-term settlement;generally requires highquality wall backfillsoil; wide base widthrequired (70% of wallheight); typicallyrequires a settlementdelay period duringconstruction

Applicable primarily to fillsituations; maximum heightof 10 m for routine designs;heights over 10 m require aspecial design

Steel soilreinforcementwith weldedwire face only

Can tolerate largelong-termsettlements; low cost

Aesthetics, unless faceplantings can beestablished; generallyrequires high qualitybackfill; wide basewidth required (70%of wall ht.)

Applicable primarily to fillsituations; maximum heightof 10 m for routine designs;heights over 10 m require aspecial design

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1210 Hydraulic Design

1210.01 General1210.02 References1210.03 Hydraulic Considerations1210.04 Safety Considerations1210.05 Design Responsibility

1210.01 GeneralHydraulic design factors can significantlyinfluence the corridor, horizontal alignment,grade, location of interchanges, and the necessaryappurtenances required to convey water across,along, away from, or to a highway or highwayfacility. An effective hydraulic design conveyswater in the most economical, efficient, andpractical manner to ensure the public safetywithout incurring excessive maintenance costsor appreciably damaging the highway orhighway facility, adjacent property, or thetotal environment.

This chapter is intended to serve as a guide tohighway designers so they can identify andconsider hydraulic related factors that impactthe design. Detailed criteria and methods thatgovern highway hydraulic design are inWSDOT’s Hydraulics Manual and HighwayRunoff Manual.

Some drainage, flood, and water quality problemscan be easily recognized and resolved; othersmight require extensive investigation before asolution can be developed. Specialists experi-enced in hydrology and hydraulics can contributesubstantially to the planning and project defini-tion phases of a highway project by recognizingpotentially troublesome locations, makinginvestigations and recommending practicalsolutions. Regions may request that the OlympiaService Center (OSC) Hydraulics Branch provideassistance regarding hydraulic problems.

Since hydraulic factors can affect the design ofa proposed highway or highway facility from itsinception, consider these factors at the earliestpossible time during the planning phase.

In the project definition phase, begin coordinationwith all state and local governments and Indiantribes that issue or approve permits for theproject.

1210.02 References(1) Existing Criteria and ReferencesExisting criteria and additional information forhydraulic design requirements, analyses, andprocedures are contained in the followingreferences:

Hydraulics Manual, M 23-03, WSDOT

Highway Runoff Manual, M 31-16, WSDOT

Standard Plans for Road, Bridge and MunicipalConstruction, M 21-01, WSDOT

Standard Specifications for Road, Bridge andMunicipal Construction, M 41-10, Amendments,and General Special Provisions, WSDOT

Utilities Manual, M 22-87, Section 1-19, “StormDrainage,” WSDOT

(2) Special CriteriaSpecial criteria for unique projects are availableon request from the OSC Hydraulics Branch.

1210.03 Hydraulic Considerations(1) The Flood PlainEncroachment of a highway or highway facilityinto a flood plain might present significantproblems. A thorough investigation considersthe following:

(a) The effect of the design flood on thehighway or highway facility and the requiredprotective measures.

(b) The effect of the highway or highwayfacility on the upstream and downstream reachesof the stream and the adjacent property.

(c) Compliance with hydraulic related environ-mental concerns and hydraulic aspects of permitsfrom other governmental agencies per Chapters220 and 240.

Design Manual Hydraulic DesignDecember 1998 Metric Version Page 1210-1

Studies and reports published by the FederalEmergency Management Agency (FEMA) andthe Corps of Engineers are very useful for floodplain analysis. The OSC Hydraulics Branch hasaccess to all available reports and can provideany necessary information to the region.

(2) Stream CrossingsWhen rivers, streams, or surface waters (wetland)are crossed with bridges or culverts (includingopen bottom arches and three-sided box culverts),consider the following:

• Locating the crossing where the stream ismost stable.

• Effectively conveying the design flow(s) atthe crossing.

• Providing for passage of material transportedby the stream.

• The effects of backwater on adjacentproperty.

• Avoiding large skews at the crossing.

• The effects on the channel and embankmentstability upstream and downstream fromthe crossing.

• Location of confluences with other streamsor rivers.

• Fish and wildlife migration.

• Minimizing disturbance to the originalstreambed.

• Minimizing wetland impact.

Also see the Hydraulics Manual Chapter 8 forfurther design details.

(3) Channel ChangesIt is generally desirable to minimize the use ofchannel changes because ongoing liability andnegative environmental impacts might result.Channel changes are permissible when thedesigner determines that a reasonable, practicalalternative does not exist. When used, consider:

(a) Restoration of the original stream character-istics as nearly as practical. This includes:

• Meandering the channel change to retainits sinuosity.

• Maintaining existing stream slope andgeometry (including meanders) so streamvelocity and aesthetics do not change inundisturbed areas.

• Excavation, selection, and placement of bedmaterial to promote formation of a naturalpattern and prevent bed erosion.

• Retention of stream bank slopes.

• Retention or replacement of streamsidevegetation.

(b) The ability to pass the design flood.

(c) The effects on adjacent property.

(d) The effects on the channel and embankmentupstream and downstream from the channelchange.

(e) Erosion protection for the channel change.

(f) Environmental requirements such aswetlands, fish migration, and vegetationre-establishment.

Do not redirect flow from one drainage basin toanother. (Follow the historical drainage pattern.)

Consult the OSC Hydraulic section for the bestguidance when channel changes are considered.

(4) Roadway DrainageEffective collection and conveyance of stormwater is critical. Incorporate the most efficientcollection and conveyance system consideringinitial highway costs, maintenance costs, andlegal and environmental considerations. Ofparticular concern are:

(a) Combinations of vertical grade and trans-verse roadway slopes that might inhibit drainage.

(b) Plugging of drains on bridges as the resultof construction projects. This creates mainte-nance problems and might cause ponding on thestructure. The use of drains on structures can beminimized by placing sag vertical curves andcrossovers in superelevation outside the limitsof the structure.

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1440 Surveying and Mapping

1440.03 ProceduresFor WSDOT projects, it is recommended thatsurveying activities include (if appropriate) butnot be limited to the following items.

(1) During the Project DefinitionPhase

(a) Include any pertinent surveying informationin the Project Summary.

(b) Research for recorded survey monumentsexisting within the project area.

(c) Determine and prioritize project surveyneeds and tasks to be completed.

• Cadastral issues

• Right of way issues

• Geodetic control issues

• Photogrammetry issues

• Other issues as needed

(2) During Design and Developmentof the Plans, Specifications, andEstimate

(a) Hold a presurvey conference.

(b) Schedule tasks with surveyors.

(c) Perform field reconnaissance, mark existingrecorded survey monuments, and determinelocation of possible new survey monuments.Also mark found unrecorded monuments forpreservation if practical.

(d) Determine impact to geodetic monumentsand notify OSC Geographic Services.

(e) See the Highway Surveying Manual to:

• Convert Washington state plane coordinatesto project datum.

• Document the procedure and combined factorused for converting between datums.

1440.01 General1440.02 References1440.03 Procedures1440.04 Datums1440.05 Global Positioning System1440.06 WSDOT Monument Database1440.07 Geographic Information System1440.08 Photogrammetric Surveys1440.09 Documentation

1440.01 GeneralThe Washington State Department ofTransportation (WSDOT) is permitted, by anagreement with the Board of Registration forProfessional Engineers and Land Surveyors,to “practice land surveying“ under the “directsupervision of either a licensed professional landsurveyor or a licensed professional engineer.”See Figure 1440-1, Interagency Agreement.

1440.02 ReferencesRCW 58.09, “Surveys -- Recording”

RCW 58.20.120, “System designation --Permitted uses”

RCW 58.24.040(8), “. . . temporary removal ofboundary marks or monuments”

WAC 332-120, “Survey Monuments -- Removalor Destruction”

WAC 332-130, “Minimum Standards for LandBoundary Surveys and Geodetic Control Surveysand Guidelines for the Preparation of LandDescriptions”

Interagency Agreement Between the WashingtonState Department of Transportation and theBoard of Registration for Professional Engineersand Land Surveyors

Construction Manual, M 41-01, WSDOT

Highway Surveying Manual, M 22-97, WSDOT

Plans Preparation Manual, M 22-31, WSDOT

WSDOT Monument Database at http://www.wsdot.wa.gov/monument/

Design Manual Surveying and MappingJune 1999 Metric Version Page 1440-1

• Determine survey collection methods.

• Collect primary, secondary, and tertiarysurvey data.

• Process and import secondary, tertiary, orother survey data into design software foruse by designers.

(f) Apply to the Department of NaturalResources (DNR) for permits for monumentsthat will be disturbed or removed (Chapter 1450).

(g) Archive new primary and secondary surveycontrol data in the WSDOT Monument Databaseand GIS, as appropriate, for future retrieval.

(h) Ensure that all survey monuments withinthe right of way of the project are shown onthe contract plans in order to avoid accidentaldamage.

(i) Develop a Record of Survey (RCW 58.09)or a Monumentation Map as required (Chapter1450).

(3) After Construction is Completed(a) Complete “Post Construction” survey asdescribed in the Highway Surveying Manual andthe Construction Manual.

(b) Have DNR Completion Report signed andstamped by the appropriate professional in directresponsible charge of the surveying work, thenfile with DNR as described in Chapter 1450.

1440.04 DatumsA datum is a geometrical quantity or set ofquantities that serves as a reference, forming thebasis for computation of horizontal and verticalcontrol surveys in which the curvature of theearth is considered. Adjusted positions of thedatum, described in terms of latitude and longi-tude, may be transformed into plane coordinateson a state system.

(1) HorizontalWAC 332-130-060 states that “The datum forthe horizontal control network in Washingtonshall be NAD83 (1991) as officially adjusted

and published by the National Geodetic Surveyof the United States Department of Commerceand as established in accordance with chapter58.20 RCW. The datum adjustment shall beidentified on all documents prepared; i.e.,NAD83 (1991).” For further information,see the Highway Surveying Manual.

(2) VerticalThe Federal Geodetic Control Subcommittee(FGCS) has affirmed the North AmericanVertical Datum of 1988 (NAVD88) as theofficial civilian datum for surveying andmapping activities in the United States. WSDOThas adopted this datum. For further information,see the Highway Surveying Manual.

1440.05 Global PositioningSystemA Global Positioning System (GPS) uses aconstellation of satellites and earth stationedreceivers to determine geodetic positions (latitudeand longitude) on the surface of the earth. Thissurvey technology is used by WSDOT personnel.See the Highway Surveying Manual for moredetailed discussions.

GPS technology is changing rapidly. The keypoint is for the designer and surveyor to select thebest tool (GPS application) for doing the survey.Often times a combination of GPS and traditional(Total Station) surveying is appropriate.

1440.06 WSDOT MonumentDatabaseThe WSDOT Monument Database providesstorage and retrieval capabilities for data associ-ated with survey control monuments set byWSDOT. This database supports and tracksthe Report of Survey Mark and aids in fulfillingWSDOT’s obligation to contribute to the body ofpublic record, thereby minimizing the duplicationof survey work.

The Internet address http://www.wsdot.wa.gov/monument/ is used to access the WSDOTMonument Database.

Surveying and Mapping Design ManualPage 1440-2 Metric Version May 2001

Design Manual MonumentationMay 2001 Metric Version Page 1450-1

1450 Monumentation

1450.01 General1450.02 References1450.03 Definitions1450.04 Control Monuments1450.05 Alignment Monuments1450.06 Property Corners1450.07 Other Monuments1450.08 Documentation1450.09 Filing Requirements

1450.01 GeneralProper monumentation is important in referenc-ing a highway’s alignment that is used to defineits right of way and the department can contributeto the body of public records and minimizeduplication of survey work by establishing andrecording monuments that are tied to a state planeand to a standard vertical datum. In addition, thedepartment is required by law to perpetuateexisting recorded monuments. (See RCW 58.09.)Consequently, the department shall providemonuments for realignments and new highwayalignments and shall perpetuate existing monu-ments impacted by a project.

Both the Department of Natural Resources(DNR) and the Geographic Services Branchmaintain records of surveys performed andsurvey monuments established. New monumentsare to be reported to both operations.

Existing monuments are not to be disturbedwithout first obtaining the DNR permits requiredby state law. DNR allows the temporary coveringof a string of monuments under a single permit.State law requires replacement of land boundarymonuments after temporary removal according topermit procedures. WSDOT control and align-ment monuments may be removed withoutreplacement if approved by the GeographicServices Branch. (Notify DNR.)

Other requirements pertaining to specificmonuments are discussed below.

Figure 1450-1 summarizes the documentationrequirements for new and existing monuments.

The region is responsible for obtaining allrequired permits before any existing monumentis disturbed and for the research to locate existingmonuments as required by WAC 332-120-030as follows:

(2) Any person, corporation, association,department, or subdivision of the state, countyor municipality responsible for an activitythat may cause a survey monument to beremoved or destroyed shall be responsible forensuring that the original survey point isperpetuated. It shall be the responsibility ofthe governmental agency or others perform-ing construction work or other activity(including road or street resurfacing projects)to adequately search the records and thephysical area of the proposed constructionwork or other activity for the purpose oflocating and referencing any known orexisting survey monuments.

1450.02 References

“Engineers and Land Surveyors,” RCW 18.43

“Surveys — Recording,” RCW 58.09

“State Agency for Surveys and Maps — Fees,”RCW 58.24

“Survey Monuments--Removal or Destruction,”WAC 332-120

“Minimum Standards for Land Boundary Surveysand Geodetic Control Surveys and Guidelines forthe Preparation of Land Descriptions,”WAC 332-130

“Manual of Instructions for the Survey of thePublic Lands of the United States 1973 BLM,U.S. Department of Interior”

1450.03 Definitions

monument, as defined for this chapter, is anyphysical object or structure which marks orreferences a survey point. This includes a pointof curvature (P.C.), a point of tangency (P.T.), aproperty corner, a section corner, a General LandOffice (GLO) survey point, a Bureau of Land

Monumentation Design ManualPage 1450-2 Metric Version May 2001

Management (BLM) survey point, and any otherpermanent reference set by a governmentalagency or private surveyor.

removal or destruction the physical distur-bance or covering of a monument such that thesurvey point is no longer visible or readilyaccessible.

1450.04 Control Monuments

Horizontal and vertical control monuments arepermanent references required for the establish-ment of project coordinates tied to a state planeand elevations tied to a standard vertical datum.By establishing and recording permanent controlmonuments, the department eliminates duplica-tion of survey work and contributes to the bodyof public records.

Horizontal and vertical control monuments arerequired for highway projects requiring thelocation of existing or proposed alignment orright of way limits. Monuments set by otheragencies may be used if within two kilometers(1.24 miles) of the project and the required datumand accuracy were used. To omit monumentationwhen it is impractical, a variance must be soughtfrom the State Survey Support Engineer.

When control monuments are required for a givenproject, either show the existing and proposedcontrol monuments on the contract plans orinclude an approved variance in the design report.

For horizontal control:

• Use North American Datum 1983, revised1991 (NAD83/91).

• Use a minimum of second order, Class IIprocedures as defined in the HighwaySurveying Manual (M 22-97).

• Provide two monuments near the beginningof the project.

• Provide two monuments near the end ofthe project.

• Provide a pair of monuments at about fivekilometer (or 3-mile) intervals throughoutthe length of the project.

For vertical control:

• Use North American Vertical Datum 1988(NAVD88). See the Highway SurveyingManual for orders of accuracy required.

• Use at least third order procedures withinproject limits as defined in the HighwaySurveying Manual.

• Provide vertical control throughout thelength of the project. Desirable spacing isat or near each milepost or every otherkilometer. Maximum spacing is fivekilometers (3.11 miles) apart.

All control monuments that are established,reestablished, or reset must be filed with thecounty engineer and DNR. Submit aMonumentation Map that has been signed bythe supervising, licensed, professional engineer,or land surveyor (or, if the monument is notused to reference right of way or land corners,submit a Record of Survey Mark).

1450.05 Alignment MonumentsAlignment monuments are permanent referencesrequired for the establishment or reestablishmentof the highway and its right of way. Generally,highway and ramp center line P.C.s and P.T.s aremonumented. Establishment, reestablishment, orresetting of alignment monuments is required onthe following highway projects:

• New highway alignment projects.

• Highway realignment projects involvingnew right of way. (Monuments are onlyrequired for the realigned highway section.)

• Highway projects where alignmentmonuments already exist.

Before an existing alignment monument isreestablished or reset, a DNR permit is required.

All alignment monuments that are established,reestablished or reset must be filed with theappropriate county engineer and DNR. A copyof a Monumentation Map is filed with the countyengineer of the county in which the monumentis located and the original is sent to the OlympiaService Center Right of Way Plans Branch. TheOlympia Service Center will forward a copy toDNR for their records.

Design Manual MonumentationMay 2001 Metric Version Page 1450-3

1450.06 Property CornersA new property corner monument will beprovided where an existing recorded monumenthas been invalidated as a direct result of a right ofway purchase by the department. The newproperty corner monument shall be set by orunder the direct supervision of a licensed profes-sional land surveyor. The licensed professionalland surveyor must record the survey with thecounty auditor and send copies to DNR andthe Olympia Service Center Right of WayPlans Branch.

1450.07 Other MonumentsA DNR permit is required before any monumentmay be removed or destroyed.

Existing section corners and BLM or GLOmonuments impacted by a project shall be resetto perpetuate their existence. After completingthe work, a Land Corner Record is required.

Other permanent monuments established by anyother governmental agency must not be disturbeduntil the agency has been contacted to determinespecific requirements for the monument. Ifassistance is needed to identify a monument,contact the Olympia Service Center GeographicServices Branch.

Resetting monuments must be done by or underthe direct supervision of a licensed professionalengineer or a licensed professional land surveyor.A copy of a Monumentation Map is filed withthe county engineer of the county in which themonument is located and the original is sentto the Olympia Service Center Right of WayPlans Branch. The Olympia Service Centerwill forward a copy to DNR for their records.

1450.08 Documentation

The following documents are to be preservedfor future reference in the project’s designdocuments file. See Chapter 330.

� A general statement about the project’simpacts on existing monuments.

� A general statement concerning newmonuments.

1450.09 Filing Requirements(1) DNR Permit

When a DNR permit is required, use theapplication form shown in Figure 1450-2a.The completed application must be signed bya licensed professional engineer or a licensedprofessional land surveyor and submittedto DNR.

Monumentation work cannot be done until DNRhas approved the permit. Verbal permission maybe granted by DNR pending the issuance of awritten permit.

After resetting the monument, the survey methodused must be filed with DNR using the comple-tion report form shown in Figure 1450-2b. Theform must be signed by a licensed professionalengineer or a licensed professional land surveyor.

(2) Monumentation Map

When a Monumentation Map is required, a plansheet is prepared. Generally, the plan sheet isbased on a right of way plan obtained from theOlympia Service Center Right of Way PlansBranch. A Monumentation Map contains adescription of all new and existing monumentsindicating their kind, size, and location. Inaddition, it must contain the seal and signatureof a licensed professional engineer or a licensedprofessional land surveyor. See the PlansPreparation Manual.

A copy of a Monumentation Map is filed withthe county engineer of the county in which themonument is located and the original is sentto the Olympia Service Center Right of WayPlans Branch. The Olympia Service Centerwill forward a copy to DNR for their records.

(3) Land Corner Record

When a Land Corner Record is required, usethe forms shown in Figures 1450-3a and 3b. Thecompleted forms must be signed and stampedby a licensed professional engineer or a licensedprofessional land surveyor and submitted to thecounty auditor for the county in which themonument is located. Copies are sent to DNRand the Olympia Service Center Right of WayPlans Branch.

Monumentation Design ManualPage 1450-4 Metric Version May 2001

Monument Documentation SummaryFigure 1450-1

SET NEW

WSDOT Control MonumentBefore: No permit required.

After: File a copy of a Monumentation Map with the county engineer. Send theoriginal to the OSC R/W Plans Branch.

Alignment MonumentBefore: No permits required.

After: File a copy of a Monumentation Map with the county engineer. Send theoriginal to the OSC R/W Plans Branch.

Property Corner Monument*Before: Engage a licensed professional land surveyor.

After: Licensed professional land surveyor files Record of Survey with countyauditor and DNR and send a copy to the OSC R/W Plans Branch.

DISTURB EXISTING*

Control MonumentBefore: Obtain DNR permit.

After: File a copy of a Monumentation Map with the county engineer. Send theoriginal to the OSC R/W Plans Branch.

Alignment MonumentBefore: Obtain DNR permit.

After: File a copy of a Monumentation Map with the county engineer. Send theoriginal to the OSC R/W Plans Branch.

Section Corner, BLM, or GLO MonumentBefore: Obtain DNR permit.

After: File Land Corner Record with the county auditor and DNR and send a copyto the OSC R/W Plans Branch.

All Other MonumentsBefore:

• Obtain DNR permit.

• Contact governmental agency.

After: File a copy of a Monumentation Map with the county engineer. Send theoriginal to the OSC R/W Plans Branch.

*Property corner monuments must be filed within 90 days of establishment, reestablishment, orrestoration.

Design Manual MonumentationMay 2001 Metric Version Page 1450-5

DNR Permit ApplicationFigure 1450-2a

Monumentation Design ManualPage 1450-6 Metric Version May 2001

DNR Completion Report FormFigure 1450-2b

Design Manual MonumentationMay 2001 Metric Version Page 1450-7

Land Corner RecordFigure 1450-3a

Monumentation Design ManualPage 1450-8 Metric Version May 2001

Land Corner RecordFigure 1450-3b

Design Manual IndexMay 2001 Metric Version Page 1

Index

AAcceleration lane, 940-7Acceleration lanes, 910-8Access, 1420-1

approach criteria, 1420-3, 1420-5approach types, 1420-6bicycle facilities, 1420-2, 1420-4, 1420-6bus stops, 1420-2, 1420-4, 1420-5control design policy, 1420-1control development, 1430-1crossroads at interchange ramps, 1420-1frontage roads, 1420-7full control, 1420-1hearing, 210-12, 1430-2hearing plan, 1430-2interchanges and intersections, 1420-3,

1420-5mailboxes, 1420-2, 1420-4, 1420-5modifications to limited access plans,

1420-8modified control, 1420-4multiple use of right of way, 1420-7partial control, 1420-2pedestrian facilities, 1420-2, 1420-4,

1420-5, 1420-6railroad approaches, 1420-6report, 1430-1report plan, 1430-1road approaches, 1420-1utilities, 1420-2, 1420-4, 1420-5

Access control, 120-7full, 1420-1modified, 1420-4partial, 1420-2

Access Point Decision Report (APD Report),1425-1

definitions, 1425-2documentation, 1425-10eight policy topics, 1425-3finding of engineering & operational

acceptability, 1425-4flow chart, 1425-14, 1425-15procedures, 1425-2references, 1425-1report and supporting analysis, 1425-4review levels, 1425-11, 1425-12

Accessible route, pedestrian, 1025-1ADA, definition, 1025-1ADIEM II impact attenuator, 720-2, 720-9,

720-12Administrative appeal hearing, 210-15Agency Request Budget (ARB), 120-15Agreements, 240-10

airspace, highway, utility, 1420-7Air quality, 240-6Airport System Plan, 120-13Airport-highway clearance, 240-4, 240-13, 630-3Airspace agreement, 1420-7Alignment

horizontal, 620-1monuments, 1450-2vertical, 630-1

Americans with Disabilities Act (ADA), 1025-1Approaches

full access control, 1420-1modified access control, 1420-4partial access control, 1420-2railroad, 1420-6road, 920-1, 1420-1

Approvalaccess hearing plan, 1430-2access report, 1430-1corridor, FHWA, 220-9DEIS, 220-6design, level of, 330-7design reviews and, 330-9, 330-10Environmental Classification Summary,

220-2FEIS, 220-8findings and order, 210-14governmental agencies, 240-1materials source, 510-2PS&E process, 330-11Study Plan and a Public Involvement Plan

(EIS), 220-3Work Order Authorization, CE, 220-9Work Order Authorization, EA, 220-10Work Order Authorization, EIS, 220-3

Archaeological sites, 220-5, 220-10, 220-11Army Corps of Engineers, 240-1Arterial HOV, 1050-1, 1050-10

Index Design ManualPage 2 Metric Version May 2001

Asphalt pavementestimating, 520-3

Attenuator, impact. See Impact attenuatorAudible warning signals, 1025-3Authorized road approach, 920-1Auxiliary lanes, 620-4, 1010-1

chain-up area, 1010-5climbing lanes, 1010-2emergency escape ramps, 1010-4left-turn, 910-6one-way left-turn, 910-6passing lanes, 1010-2right-turn, 910-8shoulder driving for slow vehicles, 1010-3slow moving vehicle turnouts, 1010-3speed change, 910-8two-way left-turn, 910-7

Average weekday vehicle trip ends (AWDVTE),920-1

BBarrier curbs, 440-6Barrier delineation, 830-5Barrier terminal

buried terminals, 710-6definition, 710-1flared terminal, 710-7, 710-23nonflared terminal, 710-7, 710-23other anchor, 710-8project requirements, 710-2

Barrier transitionbeam guardrail transitions, 710-10connections, 710-9definition, 710-1project requirements, 710-2transitions and connections, 710-10

Barriers, traffic, 710-1barrier deflections, 710-4barrier design, 710-3beam guardrail, 710-5bridge rails, 710-15cable barrier, 710-11concrete barrier, 710-12definition, 710-1delineation, 830-5documentation, 710-17dragnet, 710-16flare rate, 710-4impact attenuator systems, 720-1length of need, 710-5, 710-19

project requirements, 710-1redirectional land forms, 710-15shared use path (bicycle), 1020-13shy distance, 710-4steel backed timber guardrail, 710-14stone guardwalls, 710-15water filled barriers, 710-16

Basic design level, 410-1minor safety and minor preservation work,

410-1required safety items of work, 410-1

Basic safety, 410-1Beam guardrail. See GuardrailBerms, earth

noise barriers, 1140-2traffic barrier, 710-15

Bicycle Advisory Committee, 1020-4Bicycle coordinator, 1020-1, 1020-3, 1020-7,

1020-17Bicycle facilities, 1020-1, 1020-7

access, 1020-6alignment, horizontal, 1020-13barriers, traffic, 1020-13bicycle parking, 1020-7bicycle route, 1020-1bike lane, 1020-1, 1020-4, 1020-16bike lanes cross freeway off and on-ramps,

1020-16bike route, 1020-17bikeway, 1020-1bollards, 1020-15clearance, 1020-8, 1020-14, 1020-15crossings, 1020-9design clear zone, 1020-13design speed, 1020-13drainage, 1020-15drainage grates, 1020-17intersections, 1020-8lighting, 1020-7, 1020-15maintenance, 1020-6parking, 1020-16pavement markings, 1020-15, 1020-16,

1020-17planning, 1020-2railroad crossing, 1020-12Rules of the Road (RCW 46.61), 1020-3,

1020-16rural bicycle touring routes, 1020-2shared roadway, 1020-2, 1020-4, 1020-17

Design Manual IndexMay 2001 Metric Version Page 3

shared use path, 1020-2, 1020-3, 1020-7,1020-8, 1020-9, 1020-10, 1020-11,1020-12

sidewalks, 1020-4sight distance, 1020-14signed shared roadway, 1020-2signing, 1020-15State Highway System Plan, 1020-2storage facilities, 1020-7structures, 1020-7, 1020-14superelevation, 1020-13traffic signals, 1020-11, 1020-17tunnels, 1020-15undercrossings, 1020-15widths, 1020-8, 1020-15

Bicycle Policy Plan, 120-10Bituminous surface treatment, 520-5

estimating, 520-5Bollards, 1020-15Borrow site. See Sundry sitesBoundaries, international, 1410-2Brakemaster impact attenuator, 720-1, 720-6,

720-12Bridge rails, 710-15

concrete safety shape, 710-15pedestrian, 1025-8project requirements, 710-2thrie beam bridge rail retrofit criteria,

710-24thrie beam retrofit, 710-16

Bridge site data, 1110-1check list, 1110-5stream crossings, 1110-2

Bridges, 1120-1approach slab, 1120-3design, 1120-1end slopes, 640-9existing structures, 1120-1geotechnical investigation, 510-11horizontal clearance, 1120-2location, 1120-1medians, 1120-2new structures, 1120-1pedestrian and bicycle facilities, 1120-3protective screening for highway structures,

1120-4rail end treatment, 1120-3railroad, 1120-2rails, 710-15site design elements, 1120-1

slope protection, 1120-3slope protection at watercrossings, 1120-4structural capacity, 1120-1vertical clearance, 1120-2widths for structures, 1120-2

Bridle trail, 1020-1Budgets, 120-15Buffer strip, pedestrian, 1025-5Buffer-separated HOV facility, 1050-1, 1050-3Bulb out, 1025-1Bus facilities, 1060-1

berths, 1060-7disabled accessibility, 1060-12grades, 1060-11intersection, 1060-11lane widths, 1060-11passenger amenities, 1060-10paving sections, 1060-10transfer/transit centers, 1060-6turning path template, 1060-23, 1060-24,

1060-35, 1060-36vehicle characteristics, 1060-11

Bus stops and pullouts, 1060-7designation and location, 1060-7far-side, 1060-8mid-block, 1060-9near-side, 1060-8placement, 1060-8pullouts, 1060-9

CCable barrier, 710-11

locations on slopes, 710-23Cantilever sign supports, 820-3Capacity, highway, 610-1CAT impact attenuator, 720-1, 720-6, 720-12Cattle passes, R/W, 1410-2CE, definition, 220-1Certification of documents, 330-4Chain link

fencing, 1460-2gates, 1460-3

Chain-off areas, 1010-5Chain-up areas, 1010-5Channelization, 910-6

curbing, 910-9islands, 910-9left-turn lanes, 910-6right-turn lanes, 910-8speed change lanes, 910-8

Index Design ManualPage 4 Metric Version May 2001

Checklist, environmentalClass II and III, 220-3, 220-10definition, 220-1

City streets, 440-3Classification

functional, 440-2terrain, 440-3

Clear zone, 700-2definition, 700-1Design Clear Zone, 700-2distance table, 700-8ditch section examples, 700-12ditch sections, 700-2inventory form, 700-9recovery area, 700-2recovery area example, 700-11

Clearanceairport-highway, 240-4, 630-3bikeway, 1020-8

Climbing lanes, 1010-2Closed circuit television cameras (CCTV), 860-1Cloverleaf, 940-3Coast Guard, U.S. (USCG), 240-3, 1110-3

permit, 1110-3Collector, 440-1, 440-14Collector distributor roads, 940-8Combined hearings, 210-15Commercial approaches, 920-3Communication towers

geotechnical investigation, 510-7Comprehensive plans, 120-4, 120-5Concrete barrier, 710-12

concrete barrier terminals, 710-14shapes, 710-12

Concurrent flow HOV lane, 1050-1, 1050-3,1050-7

Condemnations, 1410-5Conflict, 910-1Conforming road approach, 920-1Construction permits, 1410-3Construction work zone traffic control strategy,

810-1Contour grading, 1310-1Contraflow HOV lane, 1050-1Control monuments, 1450-2Controllers, signal, 850-8Corner clearance, 920-1, 920-3Corridor hearing, 210-11Corridor Management Plan (CMP), 120-11

Corridor or project analysis, 325-1, 330-3sample, 330-12, 330-13

County roads, 440-3Crash cushion. See Impact attenuatorCritical slope, 700-1Cross sections

interchange ramp, 940-5roadways, 640-2rock cuts, 640-7side slopes, 640-7stepped slopes, 640-9

Cross slope, 430-2, 640-4roadways, 640-2shoulders, 640-4traveled way, 640-2

Crossovers, median, 960-1Crossroads, 910-1, 910-3

ramp terminal intersections, 940-9Crosswalks, 850-8, 1025-1

marked, 1025-6unmarked, 1025-6

Crown slope for divided roadways, 640-10Cul-de-sacs, 1420-7Culvert ends, 700-4Curb cuts, 1020-12

shared use path, 1020-12Curbs, 440-6, 910-9Current Law Budget (CLB), 120-15Curves

horizontal, 620-2superelevation, 640-4vertical, 630-2

Cut slopes, 640-10, 640-11, 640-12, 640-14,700-3

CWZTC, definition, 810-1

DDatums, surveying, 1440-2DDS. See Design Decision SummaryDE. See Design exceptionDeceleration lane, 910-8, 940-7Decision sight distance, 650-4DEIS, definition, 220-2Delineation, 830-1

guide posts, 830-4pavement markings, 830-1traffic barriers, 830-5wildlife warning reflectors, 830-5

Department of Defense (DOD), 1120-3

Design Manual IndexMay 2001 Metric Version Page 5

Designapproval level, 330-7hearing, 210-12level, 325-4speed, 430-1, 440-1, 440-3, 940-4variance, 325-4variance inventory, 330-3vehicle, 430-3, 910-4

Design Clear Zone, 700-2definition, 700-1distance table, 700-8ditch section examples, 700-12ditch sections, 700-2

Design considerations for intersections at grade,910-3

configurations, 910-3crossroads, 910-3spacing, 910-4traffic analysis, 910-3

Design Decisions Summary (DDS), 330-2Design documentation, approval, and process

review, 330-1design approval, 330-5design documentation, 330-3process review, 330-5project definition phase, 330-2project development, 330-2purpose, 330-1

Design Exception (DE), 325-4Design matrix procedures, 325-1

procedures, 325-3project type, 325-4selecting a design matrix, 325-3terminology, 325-1using a design matrix, 325-4

Designated state highways map, 120-11Developer initiated intersections, 910-13Deviation, 325-5, 330-4

documentation, 330-4documentation content list, 330-14

Diamond interchange, 940-3Direct access HOV ramp, 1050-1, 1050-5.

See HOV Direct Access Design Guide,Draft M 22-98

Directional interchange, 940-3Disabled access, transit, 1060-12Discipline Report, 220-1Distribution facilities, 620-2Ditch inslopes, 430-3DMS, definition, 860-4

DNS, definition, 220-1Documentation. See the last heading of most

chaptersdesign, 330-1environmental, 220-1

Drainage, 1210-1Drainage ditches in embankment areas, 640-9Drop lanes, 910-8Dynamic message signs (DMS), 860-4

EEA, definition, 220-1Easements, 1420-7

perpetual, 1410-3right of way, 1410-2temporary, 1410-3

Ecology, Department of, 240-6ECS, definition, 220-1EIS, definition, 220-2Elevators, 1025-9Emergency escape ramps, 1010-4Emergency vehicle preemption, 850-11Endangered species, 210-7, 220-7, 220-8, 220-10,

240-2, 240-11Environmental documents

APD report, 1425-9geotechnical report, 510-5project, 220-1

Environmental hearing, 210-11Environmental Protection Agency, 240-5Environmental Review Summary (ERS), 330-2Erosion prevention, 1350-2ERS. See Environmental Review SummaryEscape ramps, 1010-4Evaluate Upgrade (EU), 325-5, 330-4

documentation, 330-4documentation content list, 330-14

FFarmlands, 210-7, 220-5, 220-10, 220-11, 240-11Federal agencies, 240-1Federal aid

environmental categories, 220-2landscape projects, 1320-4R/W documents, 1410-6

Federal Aviation Administration (FAA), 240-4Federal Energy Regulatory Commission (FERC),

240-5Federal lands

R/W transactions, 1410-4

Index Design ManualPage 6 Metric Version May 2001

FEIS, definition, 220-2Fencing, 1460-1

chain link, 1460-2design criteria, 1460-1documentation, 1460-3fencing types, 1460-2gates, 1460-3limited access highways, 1460-1managed access highways, 1460-2procedure, 1460-3special sites, 1460-2wire fencing, 1460-2

Ferry System Plan, 120-13FHWA - WFLHD, 240-4Filing requirements, monuments, 1450-3Fill slopes, 430-3, 640-10, 640-11, 640-12,

640-14, 700-3Findings

engineering and operational acceptability,1425-4

Findings and order, 210-14plan, 220-13, 1430-2

Fish and Wildlife, Department of, 240-6Fixed objects, 700-3Flood plains, 210-7, 220-5, 220-7, 220-8, 220-10,

220-11, 1210-1Flyer stops, 1050-5FONSI, definition, 220-2Forest Service, U.S. (USFS), 240-3Freeway lighting applications, 840-11Freight and Goods Transportation System

(FGTS), 120-7Freight Rail Plan, 120-9Frontage roads, 620-3, 1420-7Full design level, 440-1

city streets and county roads, 440-3curbs, 440-6design speed, 440-3functional classification, 440-2geometric design data, 440-3grades, 440-7medians, 440-5parking, 440-6pavement type, 440-7shoulders, 440-4state highway system, 440-3state highways as city streets, 440-3structure width, 440-7terrain classification, 440-3traffic lanes, 440-4

Functional classification, 120-6, 440-1, 440-2Funding. See Programming

GG-R-E-A-T cz impact attenuator, 720-2, 720-12G-R-E-A-T impact attenuator, 720-3, 720-9,

720-10Gates, 1460-3Geographic Information System (GIS), 1440-3Geometric

design data, 440-3Geometric cross section, 640-1

medians, 640-6minimum radius for normal crown section,

640-5outer separations, 640-6roadsides, 640-7roadways, 640-2shoulders, 640-4superelevation, 640-4traveled way cross slope, 640-2turning roadway widths, 640-2

Geometric plan elements, 620-1arrangement of lanes, 620-3distribution facilities, 620-2frontage roads, 620-3horizontal alignment, 620-1horizontal curve radii, 620-2lane transitions, 620-4median width transitions, 620-4number of lanes and arrangement, 620-3pavement transitions, 620-4

Geometric profile elements, 630-1airport clearance, 630-3alignment on structures, 630-2coordination of vertical and horizontal

alignments, 630-2design controls, 630-1grade length, 630-2length of grade, 630-2maximum grades, 630-2minimum grades, 630-2minimum length of vertical curves, 630-2railroad crossings, 630-3vertical alignment, 630-1

Geometricshorizontal alignment, 620-1vertical alignment, 630-1

Design Manual IndexMay 2001 Metric Version Page 7

Geosynthetics, 530-1applications, 530-2, 530-16definition, 530-2design approach, 530-3design process, 530-12design responsibility, 530-11ditch lining, 530-6documentation, 530-11erosion control, 530-5function, 530-2separation, 530-4site-specific designs, 530-10soil stabilization, 530-5standard specification, 530-9temporary silt, 530-20temporary silt fence, 530-6types, 530-14types and characteristics, 530-1underground drainage, 530-3

Geotechnical investigation, design, and reporting,510-2

bridge foundations, 510-11buildings, 510-7cantilever signs, 510-7communication towers, 510-7consultants, 510-14documentation, 510-14earthwork, 510-4ferries projects, 510-13hydraulic structures, 510-5key contacts, 510-2luminaire, 510-7noise walls, 510-8park and ride lots, 510-7permits, 510-3reinforced slopes, 510-8rest areas, 510-7retaining walls, 510-8rockslope, 510-10sign bridges, 510-7signals, 510-7site data, 510-3surfacing report, 510-14unstable slopes, 510-9

Geotextilesdescriptions, 530-1standard specification, 530-9types, 530-15

Glare screens, 700-6, 700-16

Global Positioning System (GPS), 1440-2Governmental agencies, 240-1Grade intersections, 910-1Grades, 430-2, 440-7

bikeway, 1020-6change/city and town/adoption, 240-9maximum, 440-9, 440-10, 440-12, 440-14,

630-2minimum, 630-2ramp, 940-4shared use path, 1020-14vertical alignment, 630-2

Grading, contour, 1310-1Guardrail

beam guardrail, 710-5locations on slopes, 710-6placement cases, 710-9post installation, 710-20steel backed timber guardrail, 710-14terminals and anchors, 710-6thrie beam, 710-5, 710-24W-beam, 710-5

Guide posts, 830-4placement, 830-7

Guide sign plan, 820-4

HHAR, definition, 860-4Hazard, 700-1, 700-2

definition, 700-1fixed objects, 700-3median considerations, 700-5side slopes, 700-3water, 700-5

Headlight glare, 700-6Hearings, 210-6

access, 210-12, 1430-2administrative appeal, 210-15advertising, 210-7combined, 210-15corridor, 210-11design, 210-12environmental, 210-11, 220-7, 220-12examiner, 210-13findings and order, 210-14formal, 210-4informal, 210-4notice, 210-7open format, 210-4

Index Design ManualPage 8 Metric Version May 2001

preparation, 210-8requirements, 210-6sequence, 210-16study plan, 210-3, 210-11

Heritage tour routebarrier, 710-4designations, 120-11

Hex-Foam Sandwich impact attenuator, 720-3,720-11

High accident corridor (HAC), 1025-2High accident locations (HAL), 1025-2High occupancy vehicle (HOV) facilities, 1050-1

arterial HOV, 1050-10design criteria, 1050-7direct access. See HOV Direct Access

Design Guide, Draft M 22-98enforcement, 1050-6enforcement areas, 1050-9hours of operation, 1050-6lane termination, 1050-8operational alternatives, 1050-3planning elements, 1050-2ramp meter bypass, 1050-8SC&DI, 1050-6signs and pavement markings, 1050-9type, 1050-3vehicle occupancy designation, 1050-5

Highwayairport clearance, 240-4as city streets, 440-3

Highway Access Management ClassificationReports, 120-7

Highway advisory radio (HAR), 860-4Highway-highway separation, 1110-3Highway-railroad separation, 1110-3Highways and Local Programs Service Center,

120-10Horizontal alignment, 620-1Horizontal curve radii, 620-2HOV facilities. See High occupancy vehicle

facilitiesHydraulic considerations, 1210-1

channel changes, 1210-2flood plain, 1210-1roadway drainage, 1210-2runoff, 1210-3stream crossings, 1210-2subsurface discharge, 1210-3subsurface drainage, 1210-3

Hydraulic design, 1210-1design responsibility, 1210-3geotechnical investigation, 510-5hydraulic considerations, 1210-1safety considerations, 1210-3

IIDT, 220-3Illumination, 840-1

additional illumination, 840-3bridges, 840-5construction zones and detours, 840-4design criteria, 840-5illumination calculation example, 840-21required illumination, 840-2

Impact attenuator systems, 720-1comparison, 720-12design criteria, 720-3documentation, 720-5object markers, 830-5older systems, 720-3, 720-10permanent installations, 720-1, 720-6selection, 720-4sizes, 720-4work zone installations, 720-2, 720-9

Inertial barrier, 720-2, 720-3, 720-8, 720-12Intelligent transportation systems (ITS), 860-1

closed circuit television cameras, 860-1dynamic message signs, 860-4highway advisory radio, 860-4HOV bypass, 860-4motorist information, 860-4National ITS Architecture, 860-1public information components, 860-4surveillance, control, and driver

information, 860-1traffic data collection, 860-2traffic flow control, 860-3traffic operations center (TOC), 860-2Traffic Systems Management Center

(TSMC), 860-2Venture Washington, 860-1

Interchanges, 940-1collector distributor roads, 940-8connections, 940-6, 940-8design, 940-2lane balance, 940-6on two-lane highways, 940-9patterns, 940-2

Design Manual IndexMay 2001 Metric Version Page 9

plans, 940-10ramp design speed, 940-4ramp grade, 940-4ramp terminals, 910-12, 940-9ramp widths, 940-5ramps, 940-4sight distance, 940-4, 940-6spacing, 940-3weaving sections, 940-8

International boundaries, R/W, 1410-2Intersections at grade, 430-3, 910-1, 910-2

angle, 430-3channelization, 910-6configurations, 910-3design considerations, 910-3design vehicle, 430-3documentation, 910-13four leg intersection, 910-2interchange ramp terminals, 910-12island, 910-2, 910-9leg, 910-2median crossover, 910-2plans, 910-13right-turn corners, 910-5roundabouts, 910-2, 910-10sight distance, 910-11spacing, 910-4tee (T) intersection, 910-2traffic control, 910-12transit, 1060-11U-turns, 910-10wye (Y) intersection, 910-2

Interstate, 440-2, 440-9Irrigation, 1330-1Islands, 910-2, 910-9

compound right-turn lane, 910-9location, 910-9size and shape, 910-9

ITS, definition, 860-1

JJoint use approach, 920-2

LLabor and Industries, Department of (L&I),

240-9Land corner record (form), 1450-7Landscaping, 1300-2, 1320-1, 1330-1, 1350-1

Lane, 940-6balance, 940-6bike, 1020-1, 1020-4drop, 910-8number and arrangement, 620-3reduction, 940-6transitions, 620-4width, 430-1, 440-4

Lane lines. See Pavement markingsLaw enforcement in work zones, 810-1Left-turn lanes, 910-6

one-way, 910-6storage, 910-6two-way, 910-7

Length of need, traffic barrier, 710-5calculation, 710-19definition, 710-1on curves, 710-20

Level of Development Plan, 330-2Licensed professionals, certification by, 330-4,

1450-2, 1450-3Light standards, 840-7

geotechnical investigation, 510-7LMA impact attenuator, 720-3, 720-11Load rating, bridges, 1120-1Local agency initiated intersections, 910-13Longitudinal barrier. See Traffic barrierLow clearance warning signs, 1120-3Luminaire. See Light standards

MMailbox location and turnout design, 700-14Mailboxes, 700-4Maintenance site. See Sundry sitesManual on Uniform Traffic Control Devices

(MUTCD), 820-1, 830-1, 850-1, 860-2,1025-1, 1120-3

Maps. See also Plansmonumentation, 1450-3

Marked crosswalks, 1025-6Mast arm signal standards, 850-14Master Plan for Limited Access Highways,

120-7, 330-2Materials sources, 510-1, 510-16Matrix. See Design matrix proceduresMedian, 440-5, 640-6

design, 640-6safety considerations, 700-5transitions, 620-4

Index Design ManualPage 10 Metric Version May 2001

warrants for median barrier, 700-15width, 440-5

Median barrier, 700-5Median crossovers, 960-1

analysis, 960-1approval, 960-2design, 960-1

Memorandum of AgreementAdvisory Council, SHPO, and FHWA,

220-7Historic Preservation, 220-9

Memorandum of UnderstandingConservation Commission, 220-6Fish and Wildlife, 240-6Highways Over National Forest Lands,

240-3USCG and FHWA, 240-3WSP, 1040-2

Metropolitan Planning Organizations (MPO),120-3

Metropolitan Transportation ImprovementProgram (MTIP), 120-4, 120-14

Midblock pedestrian crossing, 1025-1Mileposts

markers, 820-4sign, 820-4

Military Traffic Management CommandTransportation Engineering Agency(MTMCTEA), 1120-3

Minor arterial, 440-2, 440-12Minor safety and minor preservation work, 410-1Modified design level, 430-1

bridges, 430-3cross slope, 430-2design speed, 430-1fill slopes and ditch inslopes, 430-3intersections, 430-3profile grades, 430-2ramp lane widths, 430-1roadway widths, 430-1stopping sight distance, 430-2

Monotube cantilever sign supports, 820-3Monotube sign bridges, 820-3Monument Database, WSDOT, 1440-2Monumentation, 1450-1

alignment monuments, 1450-2control monuments, 1450-2DNR permit, 1450-3filing requirements, 1450-3land corner record, 1450-3

monumentation map, 1450-3other monuments, 1450-3property corners, 1450-3

Mopeds, 1020-1Motorist information, 860-4

additional public information components,860-4

dynamic message signs, 860-4highway advisory radio, 860-4

Mountable curbs, 440-6MTMCTEA, 1120-3MUTCD, 820-1, 830-1, 850-1, 860-2, 1025-1

NN-E-A-T impact attenuator, 720-2, 720-9, 720-12National Highway System (NHS), 325-6, 325-7,

440-2National ITS Architecture, 860-1Natural Resources, Department of, 240-8Navigable waters, 240-3NEPA, definition, 220-1New Jersey shape barrier, 710-13Noise barriers, 1140-1

design, 1140-1documentation, 1140-4earth berm, 1140-2geotechnical investigation, 510-8noise wall, 1140-2procedures, 1140-3wall types, 1140-3

Noncommercial approaches, 920-3Nonconforming road approach, 920-2Nonrecoverable slope, 700-1Notional live load, 1120-1

OObject markers, 830-5Occupancy designation for HOV facilities,

1050-2, 1050-5Office of Urban Mobility, 120-12One-way left-turn geometrics, 910-7Open house meetings, 210-4Outer separations, 640-2, 640-6Overhead sign installations, 820-3

PPAL, 1025-2Park and ride lots, 1060-1

access, 1060-3bicycle facilities, 1060-5design, 1060-2

Design Manual IndexMay 2001 Metric Version Page 11

drainage, 1060-5fencing, 1060-6geotechnical investigation, 510-7illumination, 1060-5internal circulation, 1060-3landscape, 1060-6maintenance, 1060-6motorcycle facilities, 1060-5pavement design, 1060-5pedestrian movement, 1060-4shelters, 1060-5site selection, 1060-2stall size, 1060-4traffic control, 1060-5

Parking, 440-6Partial cloverleaf, 940-3Passing lanes, 1010-2Passing sight distance, 650-1

horizontal curves, 650-2no passing zone markings, 650-2vertical curves, 650-2

Path, bicycle. See Shared use pathPavement

transitions, 620-4widening, 620-4

Pavement markingslongitudinal, 830-1materials, 830-6transverse, 830-2

Pavement structure, 520-1asphalt concrete pavement, 520-3base and surfacing quantities, 520-7bituminous surface treatment, 520-5estimating tables, 520-1typical section, 520-6

PD. See Project DefinitionPedestrian accident locations (PAL), 1025-2Pedestrian bridge, 1120-2Pedestrian connectivity, 1025-3Pedestrian crossings at-grade, 1025-6Pedestrian design considerations, 1025-1

activity generators, 1025-4bulb out, 1025-1cross slope, 1025-6crosswalk, 1025-1diagonal ramps, 1025-7facilities, 1025-1, 1025-4funding programs, 1025-2grade, 1025-6grade separations, 1025-8

human factors, 1025-3illumination and signing, 1025-9landing, 1025-1midblock pedestrian crossing, 1025-1policy, 1025-2raised median, 1025-2refuge island, 1025-2shared use paths, 1025-5shoulders, 1025-5sidewalk ramps, 1025-7sidewalks, 1025-5transit stops, 1025-9walking and hiking trails, 1025-5walking rates, 1025-3

Pedestrian Policy Plan, 120-10Pedestrian risk projects, 1025-2Pedestrian-friendly, 1025-1Permits

construction, 1410-3geotechnical permits, 510-3governmental agencies, 240-1remove/destroy monument, 1450-5right of way, 1410-2traffic signal, 850-2

Photogrammetry, 1440-3Pit sites, R/W, 1410-2Planning, 120-1

definitions, 120-2legislation and policy development, 120-2linking transportation plans, 120-13planning and programming, 120-16planning at WSDOT, 120-7planning to programming, 120-15references, 120-1

Plansaccess hearing, 210-13, 1410-6, 1430-2access report, 1430-1environmental study, 210-3, 220-2, 220-3,

220-4findings and order, 220-13, 1430-2guide sign, 820-4interchange, 940-10intersection, 910-13limited access, 1410-2limited access, modifications to, 1420-8PS&E, R/W, 1410-4public involvement, 210-3, 220-2right of way, 1410-1, 1410-3, 1410-4traffic control, 810-1Water Pollution Control (WPCP), 240-7

Index Design ManualPage 12 Metric Version May 2001

Pollution control, 240-6Preliminary signal plan, 850-14Principal arterial, 440-2, 440-10Private land

R/W transactions, 1410-4Profile grades, 440-7Program Management Office, 120-15Programming

R/W appraisal and acquisition, 1410-6R/W funding, 1410-4

Project analysis, 325-1, 330-3sample, 330-12, 330-13

Project definition phase, 330-2Design Decisions Summary (DDS), 330-2Environmental Review Summary (ERS),

330-2Project Definition (PD), 330-3project summary, 330-2

Property corners, 1450-3Proprietary items

impact attenuators, 720-5Protective screening for highway structures,

1025-8, 1120-4Public Involvement Plan, 220-2Public Transportation and Intercity Rail

Passenger Plan for Washington State, 120-8Public Transportation and Rail Division, 120-8

QQuadGuard cz impact attenuator, 720-2QuadGuard Elite impact attenuator, 720-1, 720-7,

720-12QuadGuard impact attenuator, 720-1, 720-7,

720-12QuadTrend - 350 impact attenuator, 720-1, 720-6,

720-12Quarry site. See Sundry sites

RRailroad

approaches, access control, 1420-6crossings, 630-3preemption, 850-7, 850-11R/W transactions, 1410-4

Ramp, 940-4cross section, 940-5design speed, 940-4grade, 940-5HOV ramp meter bypass, 1050-8lane increases, 940-5

lane widths, 430-1, 940-5meters, 940-5sight distance, 940-4terminals, 910-12

REACT 350 impact attenuator, 720-2, 720-8,720-12

Recoverable slope, 700-1Recovery area, 700-2Redirectional land forms, 710-15Regional Transportation Improvement Program

(RTIP), 120-14Regional Transportation Planning Organizations

(RTPO), 120-4, 120-6Reinforced slopes, 1130-1

geotechnical investigation, 510-8Reports

access, 1430-1discipline, 220-5

Required safety items of work, 410-1Rest areas, 1030-1

geotechnical investigation, 510-7Retaining walls, 1130-1

classifications, 1130-1design principles, 1130-2design requirements, 1130-2design responsibility and process, 1130-9geotechnical investigation, 510-8selection, 1130-5

Revegetation, 1300-2, 1320-1Reviews and approvals

design, 330-9, 330-10PS&E Process, 330-11

Right of way, 1410-1appraisal and acquisition, 1410-4easements and permits, 1410-2multiple use, 1420-7plans, 1410-1programming for funds, 1410-4special features, 1410-2transactions, 1410-4

Right-turn at intersections, 910-5corners, 910-5lanes, 910-8pocket and taper, 910-8

Road approaches, 920-1, 1420-1commercial, 920-3connection category, 920-2corner clearance, 920-3design considerations, 920-2design template, 920-2

Design Manual IndexMay 2001 Metric Version Page 13

drainage requirements, 920-4noncommercial, 920-3right of way, 1410-2sight distance, 920-3spacing, 920-3type, 920-3

Roadside Classification Plan, 1300-2Roadside development, 1300-1

documentation, 1300-2recommendations, 1300-3requirements, 1300-2Roadside Classification Plan, 1300-2Roadside Manual, 1300-2

Roadside safety, 700-1clear zone, 700-2definitions, 700-1documentation, 700-7fixed objects, 700-3guidelines for embankment barrier, 700-13hazard, 700-2headlight glare, 700-6median considerations, 700-5rumble strips, 700-5side slopes, 700-3warrants for median barrier, 700-15water, 700-5

Roadsides, 640-7bridge end slopes, 640-9drainage ditches in embankment areas,

640-9roadway sections in rock cuts, 640-7side slopes, 640-7stepped slopes, 640-9

Roadway lighting applications, 840-13Roadways, 640-2

shoulders, 640-4traveled way cross slope, 640-2turning roadway widths, 640-2widths, HOV facilities, 1050-7

Rock cuts, 640-7geotechnical investigation, 510-10

Rock, investigation, 510-1ROD, definition, 220-2Roundabouts, 910-2, 910-10. See also

IL 4019.01Route, bicycle, 1020-1, 1020-17Route continuity, 940-4Route Development Plans, 120-11, 330-2Rumble strips, 700-5Runoff, 1210-3

SSafety, basic, 410-1Safety rest areas, 1030-1SC&DI, 860-1Scale sites, 1040-1Scenic byway, 120-11

barrier, 710-4School walk route, 1025-7Scoping, 220-3Section 4(f), 220-6, 220-9, 220-10, 220-11

definition, 220-2lands, 210-7, 220-7, 220-8, 240-4

Semidirectional interchange, 940-3Sentre impact attenuator, 720-3, 720-10SEPA, definition, 220-1Separated HOV facilities, 1050-2, 1050-7Shared roadway, 1020-4, 1020-17Shared use paths, 1020-2, 1025-5Shoreline Development Permit, 240-9Shoulders

cross slope, 640-4driving for slow vehicles, 1010-3functions, 440-4islands, 910-9slope, 640-4turnouts, 1010-3width, 430-1, 440-4width for curb, 440-6

Shy distance, 710-4definition, 710-1structure, 440-7

Side slopes, 700-3Sidewalk ramps, 1025-7Sidewalks, 1020-4, 1025-5Sight distance, 650-1, 940-4

bicycle, 1020-14decision, 650-4intersections, 910-11passing, 650-1road approaches, 920-3stopping, 650-2

Sight triangle, 910-11Signal

geotechnical investigation, 510-7intersection warning sign, 850-13phasing, 850-4supports, 850-13warrants, 850-4

Signed shared roadway. See Bike route

Index Design ManualPage 14 Metric Version May 2001

Signing, 820-1bikeways, 1020-15, 1020-17bridges, 820-3cantilever sign structures, 820-3design components, 820-2foundations, 820-3geotechnical investigation, 510-7ground mounted signs, 820-3guide sign plan, 820-4heights, 820-2horizontal placement, 820-4illumination, 820-3lateral clearance, 820-2lighting fixtures, 820-3location, 820-2longitudinal placement, 820-2mileposts, 820-4overhead installation, 820-3posts, 820-3service walkways, 820-4structure mounted sign mountings, 820-3vertical clearance, 820-4

Silt fence, 530-6Single point (urban) interchange, 940-3Single slope barrier, 710-13Site data for structures, 1110-1

additional data for grade separations,1110-3

additional data for waterway crossings,1110-2

additional data for widenings, 1110-4CAD files and supplemental drawings,

1110-1highway-highway separation, 1110-3highway-railroad separation, 1110-3required data for all structures, 1110-1

Slopebridge end, 640-9geotechnical investigation, 510-8protection, 1120-3protection at watercrossings, 1120-4roadways, 640-2rock cuts, 640-7shoulders, 640-4side slopes, 640-7stabilization, 1350-2stepped, 640-9traveled way, 640-2

Slow moving vehicleturnouts, 1010-3

Soil bioengineering, 1350-1design responsibilities and considerations,

1350-3streambank stabilization, 1350-2upland slope stabilization, 1350-2

Soils, 510-1investigation, 510-1

Spacinginterchanges, 940-3intersections, 910-4road approaches, 920-3

Span wire, 850-14Special permits and approvals, 240-1Speed change lanes, 910-8, 940-7Speed, design, 440-3, 940-4Stairways, 1025-9State Commute Trip Reduction Program, 120-8State Highway System Plan, 120-5, 120-10,

120-11, 330-2rural bicycle touring routes, 1020-2urban bicycle projects, 1020-2

State highways as city streets, 440-3Statewide Transportation Improvement Program

(STIP), 120-5, 120-14Steel backed timber guardrail, 710-14Stepped slopes, 640-9Stockpiles, R/W, 1410-2Stone guardwalls, 710-15Stopping sight distance, 430-2, 650-2

crest vertical curves, 650-3effects of grade, 650-3existing, 650-3horizontal curves, 430-2, 650-4sag vertical curves, 650-4vertical curves, 430-2

Storage length, left-turn lane, 910-6Strain poles

steel, 850-14timber, 850-14

Streambank stabilization, 1350-2Striping. See Pavement markingsStructural capacity, 1120-1Structure width, 440-7Structures. See BridgesStudy plan

environmental, 220-2, 220-3, 220-4value engineering, 315-2

Design Manual IndexMay 2001 Metric Version Page 15

Sundry sitespublic lands, 240-8right of way, 1410-2source of materials, 510-1

Superelevation, 640-4existing curves, 640-5intersections, 640-5, 640-27rates, 640-4, 640-24, 640-25, 640-26runoff for highway curves, 640-5runoff for ramp curves, 640-6shared use path, 1020-13

Supplement bridge site data, 1110-3Surface Transportation Program, 120-7Surfacing materials, 510-1

base and surfacing quantities, 520-7investigation, 510-1pavement structure, 520-1surfacing report, 510-14

Surveying and mapping, 1440-1after construction is completed, 1440-2datums, 1440-2during design and development of the

PS&E, 1440-1during the project definition phase, 1440-1geographic information system (GIS),

1440-3global positioning system (GPS), 1440-2photogrammetric surveys, 1440-3procedures, 1440-1WSDOT monument database, 1440-2

TTDM Strategic Plan, 120-9Temporary road approach, 920-2Terrain classification, 440-3Textured crosswalks, 1025-6Thrie beam. See GuardrailTraffic

data collection, 860-2islands, 910-9lanes, 440-4operations center (TOC), 860-2signal design, 850-4signal permit, 850-2

Traffic analysisintersections, 910-3

Traffic barrier. See Barrier, traffic

Traffic control, 810-1channelization, 910-6intersections, 910-12plan, 810-1

Traffic control signals, 850-1control equipment, 850-8crosswalks and pedestrians, 850-8detection systems, 850-10electrical design, 850-15foundation design, 850-14funding, construction, maintenance, &

operation, 850-3intersection design considerations, 850-7preemption systems, 850-11preliminary signal plan, 850-14signal displays, 850-12signal phasing, 850-4signal supports, 850-13signal warrants, 850-4strain poles, 850-14third party agreement signals, 850-3

Traffic flow control, 860-3HOV bypass, 860-4ramp meters, 860-3

Traffic interchanges, 940-1collector distributor roads, 940-8connections, 940-6, 940-8design, 940-2lane balance, 940-6on two-lane highways, 940-9patterns, 940-2plans, 940-10ramp design speed, 940-4ramp grade, 940-4ramp terminal intersections, 940-9ramp widths, 940-5ramps, 940-4sight distance, 940-4, 940-6spacing, 940-3weaving sections, 940-8

Traffic Systems Management Center (TSMC),860-2

Transit benefit facilities, 1060-1bus stops and pullouts, 1060-7disabled accessibility, 1060-12flyer stops, 1050-5grades, 1060-11intersection, 1060-11lane widths, 1060-11

Index Design ManualPage 16 Metric Version May 2001

park and ride lots, 1060-1passenger amenities, 1060-10paving sections, 1060-10priority preemption, 850-11transfer/transit centers, 1060-6vehicle characteristics, 1060-11

Transitions and connections, traffic barrier, 710-8Transitions, pavement, 620-4Transportation Demand Management Office,

120-9Transportation Facilities and Services of

Statewide Significance, 120-6Travel Demand Management Program (TDM),

120-12Traveled way, 440-2, 640-2Traveled way cross slope, 640-2Traveler services, 1030-1Trees, 700-4TREND impact attenuator, 720-3, 720-10Truck

climbing lanes, 1010-2escape ramps, 1010-4weigh sites, 1040-1

Truck-Mounted Attenuator (TMA), 720-3Turnbacks, 1420-7Turning path template, 910-14, 910-15, 910-16,

1060-23, 1060-24, 1060-35, 1060-36Turning roadway widths, 640-2

HOV facilities, 1050-7Turnouts, 1010-3Two-way left-turn lanes, 910-7

UU-turns, 910-10U.S. Coast Guard, 240-3, 1110-3Unmarked crosswalk, 1025-6Utilities

agreements, 240-10R/W transactions, 1410-4

VValue Engineering (VE), 315-1

implementation phase, 315-3job plan, 315-5procedure, 315-1selection phase, 315-1team tools, 315-7

Vegetation, 1320-1

Vehicle turning path template, 910-14, 910-15,910-16, 1060-23, 1060-24, 1060-35, 1060-36

Venture Washington, 860-1Vertical alignment, 630-1

design controls, 630-1length of grade, 630-2maximum grades, 630-2minimum grades, 630-2minimum length of vertical curves, 630-2structures, 630-2

Vertical clearancenew bridge, railroad, 1120-2new bridge, roadway, 1120-2pedestrian bridge, 1120-2structures, 1120-2

WW-beam guardrail. See GuardrailWalking and hiking trails, 1025-5Walls

geotechnical investigation, 510-8noise, 1140-2retaining, 1130-1

Warrants, 850-4, 1010-2Washington State Patrol

median crossovers, 960-2weigh sites, 1040-1

Washington’s Transportation Plan (WTP), 120-4,120-8

Waste Sites, R/W, 1410-2Watchable Wildlife Program, 120-12Water, hazard, 700-5Water quality, 240-6Weaving sections, 940-8Weigh sites, 1040-1

federal participation, 1040-4permanent facilities, 1040-2planning, development, and responsibilities,

1040-1portable facilities, 1040-3shoulder sites, 1040-4

Wetlands, 210-7, 220-5, 220-7, 220-8, 220-10,220-11, 240-1, 1210-2

Wheelchair, 1025-4Wide QuadGuard impact attenuator, 720-7Wide REACT 350 impact attenuator, 720-8,

720-12

Design Manual IndexMay 2001 Metric Version Page 17

Wideningpavement, 620-4

Widthbridge, 440-7HOV facilities, 1050-7lane, 430-1, 440-4shoulder, 430-1, 440-4

Wildlife, Department of, 240-6Wildlife warning reflectors, 830-5Wire fencing, 1460-2Work zone traffic control, 810-1

design check list, 810-2documentation, 330-4

ZZones, transition

shared use path, 1020-12