railway track sleepers

Author: qaiserkhan001

Post on 18-Oct-2015

86 views

Category:

Documents


3 download

Embed Size (px)

DESCRIPTION

types of sleepers on a railway track

TRANSCRIPT

  • 5/28/2018 railway track sleepers

    1/31

    MINISTRY OF SCIENCE AND TECHNOLOGY

    DEPARTMENT OF TECHNICAL AND VOCATIONAL EDUCATION

    DEPARTMENT OF CIVIL ENGINEERING

    CE4017-RAILWAY ENGINEERING

    (SAMPLE QUESTINS AND SOLUTIONS)

    1

  • 5/28/2018 railway track sleepers

    2/31

    SAMPLE QUESTIONS

    CHAPTER 1

    HISTORY AND DEVELOPMENT

    1. Discuss the advantages of railways.2. Give a classification of transportation. Discuss in brief.3. Enumerate the advantages and disadvantages of railway transport over other modes of

    transport facilities.

    CHAPTER 2

    TRACKALIGNMENT

    4. (a) Write a small note on the need of construction of a new railway line.(b) List the factors influencing the selection of a good railway track alignment.

    5. Discuss the requirements of a good rail alignment.CHAPTER 3

    RAILWAY SURVEYS

    6. Explain the reconnaissance survey for a new railway lines.7. Explain the preliminary survey for a new railway lines.8. Explain the location survey for a new railway lines.

    CHAPTER 4

    RAILS

    9. (a) Define the rail and describe the functions of rail.(b) What are the causes for the wear of rails?

    10.Describe the main requirements of an ideal rail section.11.Compare the flat-footed rail and bull headed rails.12.(a) Write the advantages and disadvantages of flat-footed rails.

    (b) Write the advantages of welding of rails.

    13.Describe the corrugated rail and the possible factors, which contribute to thecommencement and development of the corrugations.

    CHAPTER 5

    SLEEPERS

    14.What are the function of sleepers and requirements of a good sleeper?15.(a) List the types of sleeper.

    (b) Describe the advantages and disadvantages of timber sleepers.

    16.(a) Define the sleeper.(b) Describe the advantages and disadvantages of concrete sleepers.

    17.Describe the advantages and disadvantages of the steel sleepers.

    2

  • 5/28/2018 railway track sleepers

    3/31

    CHAPTER 6

    BALLAST

    18.(a) List the requirements of good ballast.(b) Describe the functions of ballast.

    19.What is ballast? Why is ballast used for in the railway track? Write briefly on thedifferent types of ballast used.

    CHAPTER 7

    RAIL FIXTURES AND FASTENINGS

    20.(a) List the various types of fixtures and fastenings in a permanent way.(b) Describe the functions of fish plates in a rail joint

    21.Explain briefly the following.(a)Spikes and Chairs(b)Keys, Cotters and Tie Bars(c)Bearing Plate(d)Check Rails and Guard Rails(e)M.C.I Inserts and Rubber Pads

    CHAPTER 8

    GEOMETRIC DESIGN OF TRACK

    22.(a) What do you understand by the following terms for the section of the track?i.Grade compensation on curves

    ii.Widening of gauge

    (b) List the various types of gradients that are adopted in laying a railway track.

    23.What are the elements of a simple circular curve?24.(a) A five degree curve diverges from a main curve of 4 in an opposite direction in

    the layout of a B.G. yard. If the speed on the main curve is restricted to 54.53 kmph,

    determine the speed restriction on the branch line. Assume permissible cant

    deficiency as7.5 cm.

    (b) What do you understand by cant deficiency? If an 8 curve track diverges from

    main curve of 5 in an opposite direction in the layout of a B.G. yard, calculate the

    super elevation and the speed on branch line, if the maximum speed permitted on the

    main line is 45 kmph.

    25. (a) Explain why super elevation is necessary on a curve alignment.

    (b) Explain briefly types of classification of horizontal curves.

    CHAPTER 9

    POINTS AND CROSSINGS

    26.Write short notes in the followings:(i) Left hand and right hand turn outs(ii) Theoretical nose of crossing and Actual nose of crossing(iii) Splice rails and Wing rails(iv) Point rails and Stock rails(v) Tongue rails and Stretcher bar

    3

  • 5/28/2018 railway track sleepers

    4/31

    27.(a) On a straight B.G. track, a turnout takes off as an angle of 6 42 35Angle of switch = 1 34 27

    Length of switch rail = 4.37 m

    Heel divergence = 11.43 cm

    Length of straight arm = 0.85 m.

    Determine the radius and the crossing lead.(b) A 1 in 12 turn out is to be provided on a B>G> straight track, calculate (i) radius

    of the curve lead rail (ii) lead distance, and (iii) over all length of the turn out.

    Data given:

    Heel divergence = 133 mm

    Actual length of switch rail = 6001 mm

    Theoretical length of switch rail = 6743 mm

    Distance between toe of crossing and theoretical nose of crossing = 2415 mm

    Distance between toe of crossing and theoretical nose of crossing = 1498 mm

    Distance between theoretical nose of crossing and heel of crossing = 3810 mm

    CHAPTER 10TRACK MAINTENANCE

    28.Describe the followings:(vi) Necessity of track maintenance(vii) Essentials of good track maintenance(viii) Advantages of proper track maintenance

    29.Calculate the necessary data for setting out a semi permanent diversion 20 m awayfrom the B.G. track.

    Assume: radius of the curves = 440 m

    Gradient along diversion = 1 in 100

    Straight proportion of diversion = 50 m

    Straight length between reverse curve = 30.5 m.

    30.Design the layout of a 2 m high BG semi permanent diversion for rebuilding a 4 x 6.1m bridge on 4 m high line track. Adopt economical specifications.

    4

  • 5/28/2018 railway track sleepers

    5/31

    SOLUTIONS

    CHAPTER 1

    HISTORY AND DEVELOPMENT

    1. Discuss the advantages of railways.

    Solution

    Advantages of Railways

    1. Political Advantages2. Social Advantages

    3. Economical Advantages

    1. Political AdvantagesThe political advantages of railways are as under:

    a) Railways help to unite the people of different religions, castes, customs andtraditions.

    b) Railways network has enabled the central administration to become more easyand effective.

    c) Railways have helped in the migration of the population from one region tothe other for employment opportunities.

    d) Railways have contributed a lot for developing national integration.e) Railways have helped during wars for transportation of war equipments and

    armies.

    2. Social AdvantagesThe social advantages of railway are as under:

    a) Railways provide a convenient, safe and cheap mode of transport for thecountry.

    b) Railways have broadened the social out-look of the people.c) Railways have eradicated the untouchability as passengers of different castes

    travel in the same compartment.

    3. Economical Advantages

    The economical advantages of railway are as under:

    a) Rails help in transporting the labor from places of unemployment to industrialcenters.

    b) The finish products and the goods can be speedily transported by the railwayst the places of their consumption.

    c) Industries have been developed even far from the places of the raw materials.d) During famines, the railways play a vital role of transporting the food grainsand cloths to the affected area.

    e) Rails have provided employment to millions of people and thus, rails havehelped in solving the unemployment problem.

    f) The land cost increases due to opening of railway lines.g) Rails have helped in fair distribution of population.

    5

  • 5/28/2018 railway track sleepers

    6/31

    2. Give a classification of transportation. Discuss in brief.

    Solution

    4 major type of transportation system,

    1) Land Transport2) Water Transport3) Air Transport4) Continuous flow system

    Land Transport

    (1)Highways(2)Rail Transport

    Highways

    A rubber-tired wheel on a smooth, firm roadway features the technology used by auto,trucks, busses, bicycles, motorcycles, taxis, etc.

    Railways

    Flanged-wheel- on rail (steel wheeled of rubber wheeled). Railroads rail transit (MRT, MTR, METRO, etc.)Water Transport

    (1)Inland(2)Costal(3)Ocean Nature of artificial channels and bodies of water serve as roadways. Ships, barges, pleasure craft, submarines, etc.

    Air Transport

    (1)Domestic(2)International Use of air space at a more than nominal height above the ground Jest, helicopter, etc.

    Continuous Flow Systems

    Oil Gas OtherPipelinesProvides transportation for water, sewage, petroleum, gas, steam, heat, etc.

    Belts, cable.

    Conveyors-people movers, escalators, etc.

    6

  • 5/28/2018 railway track sleepers

    7/31

    3. Enumerate the advantages and disadvantages of railway transport over other modes oftransport facilities.

    Solution

    Sr. No. Item Highway Transport Rail Transport1.

    2

    3.

    4.

    5.

    6.

    7.

    8.

    Tractive

    resistance

    Right of way

    Cost analysis

    Gradients

    curves

    Flexibility of

    movement

    Population

    Organization

    Suitability

    Pneumatic tires on road experience

    tractive resistance five times as

    compared to that of the railways.

    It is open to all types of vehicular

    vehicles including pedestrians.

    Cost of construction and its

    maintenance is less.

    Steeper gradients up to 1 in 30 and

    relatively sharper curves may be

    provided.

    Being more flexible it may even

    serve door to door.

    It pollutes the environment more.

    Highway transport of controlled

    mostly by private sectors.

    It is suitable for lighter goods and

    for passengers traveling over short

    distances.

    Tractive resistance is less

    and hence hauling capacity

    is more.

    The track being defined by

    two rails is suitable to

    trains designed for the

    track.

    Cost of construction and its

    maintenance is more.

    Flatter gradients> 1 in 100

    and curves up to 10 on

    broad gauge tracks, are

    generally provided.

    Being less flexible, the

    movement of trains is

    restricted between fixed

    stations.

    It pollutes the

    environments less.

    It pollutes the environment

    less. Railways arecontrolled and managed by

    the Govt. organization.

    It is suitable for the

    carriage of heavy goods

    and for passengers

    traveling over long

    distances.

    CHAPTER 2

    TRACKALIGNMENT

    4. (a) Write a small note on the need of construction of a new railway line.

    (b) List the factors influencing the selection of a good railway track alignment.

    Solution

    4. (a) Need of Construction of a New Track

    Construction of new railway tracks is required to meet one of the following demands.

    (1) Strategic reasons:Sometimes it is found necessary to extend the existing railway track to

    appoint of strategic importance so that in case of an emergency, army and ware equipments

    can be quickly transported from any to the other point.

    (2) Connecting trade centers:Sometimes, construction of a new railway track may be found

    necessary to connect trade centers for quick transportation of goods from the point ofproduction to the point of consumption.

    7

  • 5/28/2018 railway track sleepers

    8/31

    (3) Political demand: Sometimes, the government may be compelled to construct a new

    railway line to meet the political demand of the area.

    (4)Developing a backward area:Sometimes, for the development of a backward area, a new

    railway line may be provided, Quick transport system develops the area rapidly.

    (5) Shortening the existing route: Sometimes two stations, a new railway lie might be

    proposed for quicker movement of the goods and passengers.

    4. (b) For selection of a good alignment , the following factors are generally considered:

    (1)Obligatory points(2)Type of traffic(3)Gauge of the track(4)Geometric standards(5)Topography of the country(6)Economic considerations(7)Other considerations

    5. Discuss the requirements of a good rail alignment.Solution

    Requirements of a Good Alignment

    While selecting an alignment of a new railway line, convenience and comfort of the

    passengers must be kept in mind. An ideal alignment should fulfill the following

    requirements:

    (1) Purpose of the track:The alignment of the track should meet the basis purposes of the

    route. The railway lines are generally laid to meet the following purposes.

    a Transportation services: Railways are usually constructed to facilitate thetransportation of the goods and passengers of the area.

    b Political and strategic considerations: The railway track may be required tomeet the political demand and to link stations of strategic importance for

    defence purposes so that in case of a war, army may move from one place to

    the other quickly.

    c To connect industrial towns: Some times a railway track may be provided tolink for consumption. In other words railways boost up the trade.

    d To open up new track: A railway track may be required to tap the resources ofremote places, which are rich in natural minerals, etc.

    e Shortening the existing track: A badly aligned railway track having zig-zagroute might be required to be replaced by a track alignment having a shorter

    distance.

    (2) Feasibility:The proposed alignment of eh railway track should fit in the general planningof the country.

    (3) Economy: An alignment is said to be economical if its cost of construction and

    maintenance is least. To obtain an economical alignment, the following considerations are

    kept in mind:

    a. Distance: An economical alignment is the shortest route between the given stations. In

    practice, it is neither possible nor feasible to have a straight alignment. The track is generally

    required to be deviated to avoid unfavorable areas such as marshy land or mountainous

    terrain.

    b. Cost of construction:To obtain an economical alignment, the construction cost should be

    minimum. This can be achieved by avoiding the areas involving excessive cuttings and

    fillings, construction of long bridges, viaducts, tunnels, etc. these factors are minimized byalignment the track along or near the water shed line.

    8

  • 5/28/2018 railway track sleepers

    9/31

    c. Maintenance cost: As the maintenance cost of the track is a recurring expenditure, it

    should be minimum, long bridges, viaducts and tunnels. The steep gradients that increase the

    wear on rails should also be avoided.

    d. Operation cost: To obtain and economical alignment, it should be ensured that the

    operation cost is minimum. This may be achieved by adopting a shortest direct route and also

    by a avoiding steep gradients enroute.(4) Safety: The proposed alignment should ensure safety for the operation staff, traveling

    passengers and goods. To achieve safety, horizontal and vertical curves should be properly

    designed. The slopes of eh cuttings and fillings should be made stable and the foundations of

    the embankments should be properly maintained t avoid their failure.

    (5) Aesthetic aspects:The alignment should be laid across pleasing natural surroundings so

    that traveling passengers enjoy the journey.

    CHAPTER 3

    RAILWAY SURVEYS

    6. Explain the reconnaissance survey for a new railway lines.

    Solution

    Reconnaissance Survey

    A reconnaissance survey should provide the following information:

    1) Accurate topography of the country.2) Towns, railways, river crossings, tunnel sites, etc.3) Geological characteristics of the soil of the area affecting foundations for bridges and

    stability of the project line.

    4) Width of waterway required for rivers and drainages.5) Maximum flood levels of the intercepting natural drainages.6) Availability of building materials and labor.7) Probable radii of the horizontal curves.8) The total length of the route.9) Amount of expected earth work.10)The approximate cost of construction of each probable line.

    Factors to be kept in view during reconnaissance survey: The following factors should be

    kept in view during reconnaissance survey:

    1. Area: The reconnaissance survey should be carried out for the entire area and not alongthe line.

    2. Existing roads: Alignment of the existing roads should not be mistaken as suitable routefor the new rail track. Road alignments are seldom useful for the construction of a railwayline.

    3. Starting of route: The engineer should not reject a particular route only because its start isbad, i.e. a sudden rise of fall. He must ascertain whether the route is bad for a long

    distance thereafter.

    4. Assumption: The engineer should never declare his decision by simply assuming thenature of the ground. He should personally verify the details in the field.

    5. Survey route: Each route should be surveyed independently from either end.6. Occular illusion: The following ocular illusions should be prevented:

    a) Estimating wrong lengthb) Estimating wrong curvature

    9

  • 5/28/2018 railway track sleepers

    10/31

    c) Overlaps of hills which may observe a lake of river due to mirage. In fact no such lakeexists there.

    d) In flat countries, the observer may observe a lake of river due to mirage. In fact nosuch lake exists there.

    7. Revenue: the probable revenue from a new railway line from 15 km on either side.7. Explain the preliminary survey for a new railway lines.

    Solution

    Preliminary Survey

    For preliminary survey for large railway projects, the field work under control of

    location engineer may be divided among the following parties:

    1. Transit party.2. Leveling party3. Topographic party.

    Fieldwork of the transit party: The following steps are involved:

    1. Clearing the route from vegetative growth.2. Fixing a peg on the starting point and establishing three points in its vicinity.3. Selecting a forward station on the straight line.4. Determining the true bearing of the first traverse side by making astronomical

    observations to either sun or star.

    5. Measuring the horizontal distance of the first traverse leg with a 30 m steel tape.6. Setting up the transit at the second station and fixing the stakes on the third station as

    well as on the first station.

    7. Observing the direct or the back angle between the adjacent traverse legs.8. Clearing the proposed alignment of the route and fixing stakes at the proposed

    traverse stations.

    9. Observing the direct angles at succeeding stations accurately.10.Checking the azimuth of the first and the last lines by making astronomical

    observations. If the traverse is long, intermediate checks after about 15 km, need be

    provided for the azimuth.

    11.Connecting the traverse to triangulation stations and intersected points enroute wherepossible.

    12.Observing prominent points such as church spires, temples, mosques, pylons, etc. oneither side of the route at least from three consecutive traverse stations, to chack the

    accuracy of the instrument work.

    13.Fixing stakes at 30 m intervals and also at the ends of traverse line.14.Measuring the distance between stakes with a 30 m steel tap. Chainage is carriedforward continuously from the beginning of the survey, i.e. zero station. Every 30 m

    station is named as full station and the intermediate stations as plus stations.

    15.Fixing stakes at intersecting with roads, railways, canals, streams, etc. and alsorecording their chainages.

    16.Plotting each days work daily to detect gross mistakes and omissions.Level Party: The level party following immediately the transit party to run longitudinal

    section of the traverse line. Following steps are involved:

    (1)Determine the elevations of the ground at all stakes, intersections with roads, railwayscart tracks, on the points of changes on slope in the usual way.

    (2)Determine the bed levels, depth of water and highest flood level of intersectingstreams

    10

  • 5/28/2018 railway track sleepers

    11/31

    (3)Established bench marks on objects which are likely to be permanent such as rocks,wells, tree toots, etc, at about 500 meter intervals and give their full descriptions to be

    referred to for subsequent work.

    (4)Read the staff to the nearest 0.01 m at full stations and points of he change on slopeand up to 0.005 m at transit points, transit stations and benchmarks.

    (5)Check the leveling work by connecting the level lines to the existing permanentbenchmarks or G.T.S. benchmarks enroute.

    (6)Plot the profile of the ground daily along the traverse line on the following scale:Project Horizontal Scale Vertical Scale

    Railways 1:2000 1:200

    Topographic Party: The topographic party prepares the topographic map of the narrow belt

    along the route. The following steps are involved:

    (1)Plotting the natural and artificial details, rivers, streams, roads, railways, canals,villages, property lines, etc.

    (2)Plotting the contours at suitable vertical interval.(3)Collecting of the information regarding the character of land, cultivation, excavation,

    rocky feature, ect.

    8. Explain the location survey for a new railway lines.

    Solution

    Location Survey

    Location survey is carried out in the following two stages:

    1. Office location survey2. Field location survey

    Office location survey: the following steps are involved:

    (1)Draw the straights along the most suitable alignment of the route in pencil.(2)Draw the curves by means of a curve template of known degrees of curvature.(3)Prepare a profile along the new line with the help of contours on the map and make

    the grade line on the profile in pencil.

    While choosing the probable location of the route, the following factors are considered:

    (i) Minimum gradient.(ii) Minimum curvature(iii) Equalization of the earthwork.(iv) Heavy earthwork.(v) Minimum number of expensive bridges.(vi) Minimum number of retaining and breast walls.

    Field Location Survey: It is carried out to set out on the ground the alignment of the route,

    finally decided on the preliminary plan. Minor changes are permissible to be made in the field

    at this stage if found necessary. The central line of the projected line is set out on the ground

    as follows.

    (1)From the preliminary map, scale off the positions of the various points to betransferred on the ground. To do this, perpendicular offsets may be made form the

    traverse line. The chainages of the intersections of the line with main traverse may be

    ascertained and if necessary, the angles and distances may also be used.

    (2)Prolong the adjoining tangents and find their point of intersection. Measure the angleof intersection carefully.

    11

  • 5/28/2018 railway track sleepers

    12/31

    (3)Knowing the radius of the curves and the angle of intersection of tangents, computethe necessary data for setting out the simple curve.

    (4)Drives stakes at every 30 m intervals and hubs at all intermediate theodolite stationsintersection points of the tangents and the point of tangencies of eh curves. Give their

    proper reference in the field book.

    (5)Draw sketches with proper dimensions for important features such as roads, railways,streams, etc,. on the right hand side of the field book.

    (6)Carrying out the leveling over the located line. Prepare a profile and establish asuitable the profile.

    (7)Plot the finally located line known as filed location on the preliminary map andcomplete the profile.

    (8)Show vertical curves on the final profile.(9)Calculate the approximate quantities of eh earthwork by drawing cross-sections of the

    located line on the preliminary contour map.

    (10) Depict all importance features in the close proximity of the line i.e all thepoint where hubs are set, all the benchmarks and the boundaries of private properties

    on the preliminary map.(11) Collect the names of the owners of private properties to facilitate the

    acquisition of the land for the permanent way.

    CHAPTER 4

    RAILS

    9. (a) Define the rail and describe the functions of rail.

    (b) What are the causes for the wear of rails?

    Solution

    (a) Rail

    The high carbon rolled steel sections which are laid end to two parallel lines over

    sleepers to provide a continuous and level surface for the trains to move and for

    carrying axle loads of he rolling stock, are called rails.

    Functions of the Rails

    The main functions of rails in a railway track are as under:

    (1)Rails provide a continuous and level surface for the movement of the trainswith minimum friction with steel wheels of the rolling stock.

    (2)Rails provide strength, durability and lateral guidance to the track.(3)Rails transmit the axle load to sleepers, which transfer the same load to the

    underlying ballast and formation.(4)Rails bear the stresses developed due to heavy vertical loads, breaking forces

    and temperature variance.

    (b) Causes for the wear of the rail

    The main causes of rail wear are as under:

    (1)The impact of moving loads.(2)The force exerted by the locomotive during acceleration.(3)The force exerted by the locomotive while retardation.(4)The force exerted by the wheel brakes.(5)The abrasion due to rail wheel interaction.(6)Climatic conditions, i.e. temperatures, rain, sand, etc.

    12

  • 5/28/2018 railway track sleepers

    13/31

    10. Describe the main requirements of an ideal rail section.

    Solution

    An Ideal Rail Section

    The main requirements of an ideal rail section are as under:(1)The section of the rail should be such that the load of eh wheels is transferred to

    the sleepers without exceeding the permissible stresses.

    (2)The section of the rail should be able to withstand the lateral forces caused due tofast moving trains.

    (3)The underside of the head and top of the foot of the rail section should be of suchaslope that the fishplates fit snugly.

    (4)The center of gravity of the rail section should preferably coincide the center ofthe height of the rail so that maximum tensile and compressive stresses are nearly

    equal.

    (5)The web of the rail section should be such that it can safely bear the vertical loadwithout buckling.

    (6)The head of the rail should be sufficiently thick for adequate margin of verticalwear.

    (7)The foot of rail should provide sufficient bearing area on the underlying sleepersso that the compressive stresses on the timber sleeper remain within permissible

    limits.

    (8)The section of the rails should be such that the ends of two adjacent rails can beefficiently jointed with a pair of fish plates.

    (9)The surfaces for rail table and gauge face should be sufficiently hard to resist thewear.

    (10) The contact area between the rail and wheel flange should be as large aspossible to reduce the contact stresses.

    (11) The specimen of rail should be able to withstand the blow of a falling weightin the test specified by the specifications.

    (12) The composition of the steel should conform to the specifications adopted forits manufacture by Open Hearth of Duplex Process.

    (13) The overall height of the rail should be adequate to provide sufficient stiffnessand strength as a simply supported beam.

    (14) The stiffness of a rail section depends upon the moment of inertia. Theeconomical design should provide maximum moment of inertia per unit weigh of

    rail with due regard to other factors.

    (15) The section modulii of the rail section and that of a pair of fish plates shouldbe adequate so as to keep the rail and fish plates within permissible limits.(16) The foot of the rail should be wide enough so that the rail is stable against

    overturning.

    13

  • 5/28/2018 railway track sleepers

    14/31

    11. Compare the flat-footed rail and bull headed rails.

    Solution

    Comparison of flat-footed and bull headed rails

    Flat-footed rails Bull headed rails These are more strong for the same cross-

    sectional area and weight.

    Bearing plates for fixing these rails onwooden sleepers are required.

    Fastening of rails to sleepers is less costlyon wooden sleepers.

    Arrangement and maintenance of pointsand crossing is simple and cheaper.

    The rolling wheels affect the rail fittingsand thus disturb the alignment.

    Daily inspection of the track with theserails, is not required.

    Initial cost of these rails is low. Replacement procedure for these rails is

    easy.

    These rails provide more rigidity t thevertical load.

    The maintenance cost is less. These are more suitable due to stability

    economy and strength.

    These are less strong for the same cross

    sectional area and weight.

    Bearing plates for fixing these rails on

    wooden sleepers are not required.

    Fastening of rails to sleepers is more

    costly on wooden sleepers.

    Arrangement and maintenance of pointsand crossing is complicated and costlier.

    The rolling wheels do not affect the railfittings quickly. These maintain good

    alignment.

    Daily inspection of these rails for thewooden keys, is required.

    Initial cost of these rails is high. Replacement procedure for these rails

    is complicated.

    These rails provide less rigidity t thevertical load.

    The maintenance cost is more. These are more suitable where lateral

    loads are more important than verticalload.

    12. (a) Write the advantages and disadvantage of flat-footed rails.

    (b) Write the advantages of welding of rails.

    Solution

    (a) Advantages of the Flat-footed Rails

    It provides better rigidity and stiffness to the track to resist both lateral and vertical forces.

    (1)It is very simple to fix these rails to the sleeper, with the help of spikes. Neither chairsnor keys are required in the case of flat-footed rails.

    (2) Maintenance of the points and crossings of flat-footed rails is very simple.(3)The cost of construction of flat-footed rails is lesser than that of the other types of

    rails.

    (4)These rails are less liable to develop kinks and thus provide a more regular top surfacethan the other types of rails.

    (5)These rails distribute the train load over a large area on the sleepers. Flat-footed railsprovide greater track stability and also provide longer life to the sleepers.

    (6)The rail failures are few and thus the maintenance cost is low.Disadvantages

    However, in case of flat-footed rails, the impact of rolling wheels directly affects the rail

    fittings. This is why the fittings of flat-footed rails get loosened more frequently than inthe case of bull-headed (B.H) rails.

    14

  • 5/28/2018 railway track sleepers

    15/31

    (b) Advantages of Welding of Rails

    The main advantages of welding of rails are as under:

    (1)Welding of rails increases the life of the rails due to decrease in wear of theends.

    (2)Welded rails provide more comfort to the passengers due to smooth running ofwheels over welded joints.

    (3)Welding of rails reduces the creep because frictional resistances increase withthe increase in rail length.

    (4)As discontinuity of rails is reduced, the defects such as hammering rail joints,displacement of joint, disturbance in alignment and running surface, are also

    eliminated.

    (5)A welded rail panel provides better track circuiting on the electrified tracks.(6)Welded rails provide better performance and reduce the effects of impact on

    large span bridges.

    (7)Long welded rail length dampens the intensity of high frequency vibrationsdue to moving loads.

    (8)Welding increases the life and decreases the wear of rails.(9)By welding of rails, the cost of track construction decreases due to elimination

    of a large number of rail joints.

    (10) Fast and heavy traffic may be permitted on track with welded rails.(11) The use of long welded rails, affords better longitudinal, lateral and

    vertical stability to the track.

    (12) In a welded rail panel, the number of joints is less. This saves the fuelconsumption as it eliminates the loss of strain and impact energy at the rail

    joints.

    (13) In welded rail panels, the risk of sabotage and accidents, areconsiderably reduced.

    (14) Welding of rails reduces the maintenance cost by about 20% to 40%.13. Describe the corrugated rail and the possible factors, which contribute to the

    commencement and development of the corrugations.

    Corrugated rail

    The rails whose top surface develops alternate ridges and hollows varying in shape

    and size (0.05 mm to 0.4 mm in depth), 2 to 8 cm apart, are called corrugated rails, when

    vehicles pass over such corrugations, an unpleasant noise is created, probably due to thelocking of air in the corrugations. Such rails are also called roaring rails.

    The possible factors, which contribute to the commencement and development of the

    corrugation, are:

    (1)High speed of running trains.(2)Rigidity of railway track.(3)Excessive tight or loose gauge.(4)Non-uniformity of the diameter of locomotive wheels.(5)Coning of wheels.(6)Steep gradients.(7)Slippage of locomotive wheels.(8)Small spacing between driving axles of the locomotives.(9)Soft and loose formation.

    15

  • 5/28/2018 railway track sleepers

    16/31

    (10) Presence of high humidity and dust in the atmosphere.(11) Use of light wagons and coaches.(12) Sudden application of brakes.(13) Using a steel of high nitrogen content and high tensile strength.(14) Vibrations of the rails.(15) Excessive phosphorus content in the steel composition.(16) Long tunnels.(17) Electrified rail track

    CHAPTER 5

    SLEEPERS

    14. What are the function of sleepers and requirements of a good sleeper?

    Solution

    Functions of SleepersIn a railway track, sleepers perform the following functions:

    (1)To hold the rails t proper gauge in all situations. i.e. exact gauge along straightsand flat curves, slightly loose on sharp curves and slightly tight in diamond

    crossings.

    (2)To support the rails firmly and evenly throughout.(3)To distribute the load transmitted through rails over large area of ballast

    underneath or to the bridge girders as the case may be.

    (4)To hold the rails to proper level in turnouts and crossovers, and at 1 in 20 in wardslope along straight tracks.

    (5)To provide and elastic medium between the rails and ballast and also to absorb thevibrations caused due to moving axle loads.

    (6)To maintain proper alignment of the track. On curves proper cant is provided byraising the outer rail and tamping he required quantity of ballast bellow th rails.

    (7)To provide the general stability of the permanent way throughout.(8)To provide the insulation of track for the electrified for signaling.(9)To provide easy replacement of the rail fastenings without any serious traffic

    disturbances.

    Requirements of a good Sleeper

    A good sleeper should meet the following requirements:

    (1)The initial cost and the maintenance cost of the sleepers should be low.(2)The fittings required for fixing the rails on to the sleepers, should be simple whichcan be easily adjusted during the maintenance.(3)The crushing strength fo the sleepers should be more with moderate weight.(4)They should be able to maintain a perfect alignment, gauge and levels of the rails

    and should afford efficient adjustment and maintenance.

    (5)They should provide sufficient bearing area to hold the rail seats and for theballast to be supported on, to resist the crushing due to movement of heavy axle

    loads.

    (6)The sleeper spacing should be such as t remove and replace the ballast duringregular maintenance operation.

    (7)They should be capable to resist the shocks and vibrations caused due to fastmoving vehicles at high speeds.

    16

  • 5/28/2018 railway track sleepers

    17/31

    (8)They should provide insulation facilities for track circuiting in the electrifiedsections.

    (9)The sleepers should be strong enough to withstand the pressuer during packingprocess.

    (10) The sleepers should be of such a design that they remain in their positions anddo not get disturbed due t moving trains.

    (11) The material used for the sleeper be such that it does not attract the sabotageand the theft qualities.

    15. (a) List the types of sleeper.

    (b) Describe the advantages and disadvantages of timber sleepers.

    Solution

    (a) Types of Sleepers1. Timber sleepers2. Steel sleepers3. Cast iron sleepers4. R.C.C sleepers5. Pre-stressed concrete sleepers.

    (b) Advantages and disadvantage of wooden Sleepers

    Advantages of wooden Sleepers

    The wooden or timber sleepers possess the following main advantages:

    (1)They have proved very useful for heavy loads and high-speed trains.(2)They are cheap and easy to manufacture.(3)They can be handled easily without any damage.(4)They maintain the correct alignment.(5)They are most suitable for track circuiting.(6)They can be used with or without ballast.(7)They can be used for gauntlet tracks.(8)They are suitable in the areas having yielding formations.Disadvantages of Wooden Sleepers

    They are easily subjected to wear and decay due to various factors, i.e. vermin, white

    ants, rail-cutting, warping, etc. Hence, these have a short life.

    (1)They do not maintain the gauge accurately.(2)They easily develop cracks with beater packing.(3)They require the highest maintenance cost as compared to other types of sleepers.(4)They get easily disturbed from their positions under heavy loads.(5)They need special treatment for fire protection.(6)Their scrap value is low.(7)They are not suitable for modern LWR track because of their lighter weight.

    16. (a) Define the sleeper.

    (b) Describe the advantages and disadvantages of concrete sleepers.

    Solution

    (a) Sleeper

    Wooden, cast iron or R.C.C members which are laid transverse to the track alignment

    to support the rails and to transfer the load from the rails to the underlying ballast are called

    wooded sleepers, cast iron sleepers or R.C.C. sleepers respectively.(b) Advantages and Disadvantages of Concrete Sleepers

    17

  • 5/28/2018 railway track sleepers

    18/31

    Advantages

    (1)The concrete sleepers are quite heavy and thus provide longitudinal, lateral andvertical stability. Because of their weight, these sleepers are more suitable to LWR

    tracks.

    (2)The concrete sleepers result in reduced rail bending stresses.(3)The concrete sleepers reduce the wear of rolling stocks.(4)The concrete sleepers produce less vertical motion and thus provide a comfortable

    journey due to less noise.

    (5)The concrete sleepers have flat bottoms. Thats why mean modern method oftrack maintenance i.e. MSP and machine maintenance can be suitably employed.

    (6)The concrete sleepers are neither in flammable nor subjected to damage bycorrosion or termite.

    (7)These sleepers have a long useful life of 50 years. It means rail and sleeperrenewals can be matched.

    (8)The concrete sleepers with their fastening system maintain gauge, cross levels,twist, alignment, longitudinal level and unevenness of the track.

    (9)The concrete sleepers are suitable for track circuiting.(10) The concrete sleepers can be manufactured from local resources.Disadvantages

    (1)They are not economical because of high cost of construction.(2)In case of derailments, heavy damage is caused.(3)High standard of maintenance of track is required.(4)The design and construction are both complicated.(5)They are more rigid.(6)They do not have any scrap value.

    17.Describe the advantages and disadvantages of steel sleepers.Solution

    Advantages of steel Sleepers

    The steel sleepers possess the following advantages:

    (1)They are manufactured by a simple operation.(2)They can be easily handled as theses are light in weight as compared to other

    types of sleepers. Hence, damages during handling and transporting are less.

    (3)Less number of fastenings are required and that too simple in nature.(4)The maintenance and adjustment of gauge are easy as compared to the other of

    sleepers.

    (5)These sleepers are rolled sections in one piece.(6)Their life is longer than that of other types of sleepers.(7)They provide better lateral rigidity to the track.(8)They are not attacked by vermins.(9)They are not susceptible to fire hazards.(10) Their scrap value is good.

    Disadvantages of Steel of Sleepers

    The steel sleepers possess the following disadvantages:

    (1)They get easily rusted and corroded.(2)They develop cracks at rail seats or near lugs.(3)Their lugs get broken easily.(4)The steel sleepers do not provide effective track circuiting.

    18

  • 5/28/2018 railway track sleepers

    19/31

    (5)The steel sleepers can only be for the type of rails for which theses aremanufactured.

    (6)These develop the tendency to become center bound because of slope at bothends.

    (7)The overall cost of steel sleepers is more than that of timber sleepers.CHAPTER 6

    BALLAST

    18. (a) List the requirements of good ballast.

    (b) Describe the functions of ballast.

    Solution

    (a) Requirements of Good Ballast

    Ideal ballast should possess the following characteristics:

    (1)It should resist crushing under dynamic loads.(2)The designed depth of the ballast should be able to distribute the weight of passing

    trains on the formation underneath uniformly.

    (3)It should not make the track dusty due to powder formation under dynamic wheelloads.

    (4)It should be reasonably elastic.(5)It should have resistance to abrasion and weathering(6)It should be non-porous to provide durability to the ballast.(7)It should hold the sleepers laterally and longitudinally under all conditions traffic,

    especially on the curves.

    (8)It should be able to facilitate easy drainage to rain water.(b) Functions of Ballast

    The main functions of ballast of a railway track are as under:

    (1)It provides a hard and level bed for the sleepers.(2)It holds the sleepers in proper position during the passage of moving trains.(3)It provides to some extent an elastic bed for the track.(4)It transmits and distributes the moving load of the trains from the sleepers to the

    formation uniformly.

    (5)It protects the formation surface from direct exposure to sun, rain and frost.(6)It provides a proper drainage to the track, keeping the sleepers in dry condition.(7)It obstracts the growth of vegetations at the track formation.(8)It provides proper super elevation to the outer rail on curves.(9)It provides an easy means for correcting the unevenness of the track.(10) It provides the lateral and longitudinal stability to the track(11) It protects the sleepers from capillary moisture of formation.(12) It provides a media for absorption of all impacts caused by rolling stock.

    18.What is ballast? Why is ballast used for in the railway track? Write briefly onthe different types of ballast used.

    Solution

    Ballast

    The material used as an elastic cushion between the sleeper and the top of heformation, is called Ballast

    19

  • 5/28/2018 railway track sleepers

    20/31

    Types of Ballast

    Keeping in vies the availability, workability, durability and strength of the ballast

    different materials have been used as ballast. The most important types of ballast

    materials used in.

    (1) Broken stones (2) Gravels

    (3) Sand (4)Moorum(5) Cinder (or ash) (6) Brick bats

    (7) Kankar (8) Ballast earth.

    Ballast Size

    The broken stones either of too big size or too small size are found unsuitable for

    railway ballast. The size of ballast depends upon the type of sleeper, method of

    maintenance and the location of the track. The ballast which contains stones varying

    in size from 20 mm to 50 mm with reasonable proportion of intermediate sizes, is

    considered a best ballast for obtaining better interlocking.

    Accordingly, the following sizes have been recommended on India railways.

    1. for wooden sleeper tracks .. 50 mm

    2. for steel sleeper tracks .. 40 mm3. for points and crossings .. 25 mm

    Sub-Ballast and Blanket

    Sub-ballast: A layer of suitable material interposed between the stone ballast and the

    formation soil is called sub-ballast.

    Function of sub-ballast: The function of eh sub-ballast is to distribute the loads of the rolling

    stock more evenly and over lager area of the formation soil.

    Blank: The layer of a suitable material provided on the top of a poor formation is called a

    blanket.

    Functions of blanket: The functions of a blanket are:

    (1)It improves the bearing capacity of the formation.(2)It avoids interpenetration of ballast and the soil.(3)It avoids the formation of ballast pockets.(4)It prevents the bottom soil to heave up and thus avoids mud pumping conditions.(5)It safely drains off water from the top ballast.

    CHAPTER 7

    RAIL FIXTURES AND FASTENINGS

    20. (a) List the various types of fixtures and fastenings in a permanent way.

    (b) Describe the functions of fish plates in a rail joint

    Solution

    (a) The various types of rail fixtures and fastenings commonly used in a permanent

    way are the following:

    1. Fish plates2. bolts3. Spikes4. Chairs5. Keys, cotters and tie bars6. Bearing plates7. Guard rails8. Check rails9. M.C.I. insert

    20

  • 5/28/2018 railway track sleepers

    21/31

    10.Rubber pads(b) Functions of the fish plates

    The main functions of fish plates are as under.

    (1)They keep the rail section in vertical and horizontal plane so as to maintaincontinuity of rails.

    (2)They allow free longitudinal movement of rails.(3)They provide the necessary expansion gap at the joint.(4)They provide the stability and strength to the rail joint.(5)They support the underside of the head of rail and top of the foot of rail.(6)They resist the stresses due t lateral and vertical bending movements without

    getting distorted.

    (7)They absorb the shock caused by the jumping of the wheel over the expansiongap.

    21. Explain briefly the following.

    a. Spikes and Chairsb. Keys, Cotters and Tie Barsc. Bearing Plated. Check Rails and Guard Railse. M.C.I Inserts and Rubber Pads

    Solution

    (a) Spikes

    Spikes are used for fixing the rails on sleepers with or without bearing plates below

    the rails. A good spike should hold the rail properly so as to obtain perfect gauge. It should

    also be strong enough t resists the motion of the rails. It should be cheap and of such a design

    the fixing and removing it, is easy.

    The various types of spikes commonly used on Indian Railways are:

    (1)Dog spikes(2)Screw spikes(3)Round spikes(4)Elastic spikes.

    Chairs

    Chairs are used for holding double headed (D.H) and bull headed (B.H) rails on the

    sleepers with proper gauge. The chairs are invariably made of cast iron and they distribute the

    load from the rail on the sleeper through their flat bottoms.

    (b) Keys, Cotters and Tie BarsKey: A small tapered piece of wood or metal, which is used to fix a rail to the chair, is known

    as a key. The following types of metal keys are in common use:

    (1)Stuarts key(2)Morgan key(3)Coiled key

    Cotters: The cotters are used for fixing the tie bars with cast iron sleepers. A cotter is a wedge

    shaped mild steel plate with a split in either horizontal or vertical plane.

    Cotters

    M.S Tie Bars: Mild steel tie bars are used for connection and holding the pots or bowls

    together.

    21

  • 5/28/2018 railway track sleepers

    22/31

    (c) Bearing Plates

    The rectangular plates made of either mild steel, cast iron, wrought iron, or malleable

    steel which are interposed between the foot of a flat footed rail and wooden sleeper to

    distribute the load on a larger area, are called bearing plates. The bearing plates are

    required not only to distribute the load but also to reduce the rubbing acton of the rail

    seat on the sleeper. These also limit the compressive stresses on the sleeper. The frictionbetween the bearing plate and the sleeper reduces the lateral forces on the spike and

    thus these help to improve the gauge holding capacity of the sleeper.

    (d) Check Rails

    The rails, which are introduced along the inner rail of a track on sharp curves for

    reducing the wear of rails, are called check rails. Check rails are also provided along the

    straight rails opposite the crossings in turnouts

    Guard Rails

    The rails, which are provided on bridges of long spans with open floor, parallel to the

    running rails in order t prevent derailed wheels from falling off the bridge, are called guard

    rails. These are fastened to sleepers at a fixed distance apart from either running rail in inter

    rail space.Guard rails are also provided on level crossing to provide a path way clearance to the

    running wheels.

    (e) M.C.I Insets

    The Malleable Cast Iron (M.C.I) inserts are fixed into the concrete during their

    manufacturing process.

    The inserts are of two types:

    (1)Stem type M.C.I.: These inserts are used in normal pretensioned concretesleepers. The weight of the system insert is 1.6 kg per piece.

    (2)Gate type M.S.I. insert: These inserts are used in post-tensioned concretesleepers. The approximate weight of gate type M.C.I. insert is 1.7 kg per

    piece.

    Rubber Pads

    A rubber pad is interposed between the food of rail and concrete sleeper. The main

    functions of a rubber pad are:

    (1) It dampens and absorbs the vibrations of the rail.(2) It easily absorbs the shocks.(3) It resists the lateral movement of the rail.(4) It prevents abrasion of the rail bottom surface.(5) It provides good electrical insulation for an electrified track.

    CHAPTER 8GEOMETRIC DESIGN OF TRACK

    22. (a) What do you understand by the following terms for the section of the track.

    i. Grade compensation on curvesii. Widening of gauge

    (b) List the various types of gradients that are adopted in laying a railway track.

    Solution

    (a) (i) Grade compensation

    Whenever a train is pulled along a curve, an additional tractive force isrequired. The ruling gradient is the maximum gradient on a particular section of

    the track. If a curve lines on a ruling gradient, the total resistance due to the

    22

  • 5/28/2018 railway track sleepers

    23/31

    gradient and curvature will exceed the ruling gradient. In order to avoid the total

    resistance beyond the permissible ruling gradient, the gradients are reduced on

    curves. This reduction in gradient is known as grade compensation on the curves.

    The curve resistances are generally expressed as a percentage per degree of a

    curve.

    B.G.track .. 0.04% per degreeM.G. track .. 0.03 5 per degree

    N.G track ..0.02% per degree

    (ii) Widening of gauge on Curves

    Due to impounding action of the wheels on curves, the gauge of the track gets

    widened and the rails get tilted outward. To prevent the tendency of tilting the rail

    outward the gauge of the track on curves is suitably widened. The amount of

    widening of gauge depends on the radius of the curve, gauge and rigid wheel base

    of the vehicles. The most common formula used fro determination of extra width of

    gauge is:

    R

    xLBd

    125)( 2

    where

    d = extra width of gauge in mm.

    B = rigid wheel base in meters

    R = radius of the curve in meters

    L = lap of the flange in meters

    hhD )(2

    where

    D = diameter of wheel in mm

    H = depth of wheel flange below top of the rail

    Note. The following points may be noted.

    (i) The extra width of gauge should not exceed 25 mm for B.G. tracks and 16 mmfor M.G. tracks.

    (ii) The general practice on Indian Railways is not to width the gauge on curves

    less than 4

    (b) Various Types of the Gradients

    (1)Ruling gradients(2)Momentum gradients(3)Pusher gradients(4)Gradients in station yards.

    23. What are the elements of a simple circular curve?

    Solution

    Elements of a Simple Curve

    1. Back tangent. The tangent T1 I at T1, the point of commencement of the curve, iscalled back tangent.

    23

  • 5/28/2018 railway track sleepers

    24/31

    2. Forward tangent. The tangent I T2at T2, the end point of the curve, is called forwardtangent.

    3. Point of intersection. The point I where back tangent when produced forward and theforward tangent when produced backward interest, is called the point of intersection.

    4. Angle of intersection. The angle between the back tangent I T1 and the forwardtangent I T2is called the angle of intersection of the curve.

    5. Angle of deflection. The angle through which forward tangent deflected is calledangle of deflection of the curve. It may be either to the either to the right or to the left,

    it is generally denoted by.

    6. Point of commencement. The point T1 where the curve originates from the backtangent is called the point of commencement of the curve. It is also sometimes known

    as point of the curve.

    7. Point of tangency. The point T2where the curve joins the forward tangent is calledpoint of tangency.

    8. Deflection angle to any point on the curve. The angle between the back tangent andthe chord joining the point of commencement t that point on the curve, is called

    deflection angle of the point. The deflection angle to the point A on the curve is I T 1A which is generally denoted by .

    9. Tangent distance. The distance between the point of intersection and point ofcommencement of the curve or distance between the point of intersection and point of

    tangency, is called the tangent.

    10.Length of the curve. The total length of the curve from the point of commencement tothe point of tangency is called length of the curve.

    11.Long chord. The chord joining the point of commencement and point of tangency iscalled long chord.

    12.Mid-ordinate. The ordinate joining the mid point of the curve and long chord is calledlong chord.

    13.Normal chord. A chord between two successive regular pegs on the curve is called anormal chord.

    14.Sub-chord. When a chord is shorter than the normal chord. It is called a sub-chord.These sub-chords generally occur at the beginning and at the end of the curve.

    24. (a) A five degree curve diverges from a main curve of 4 in an opposite direction

    in the layout of a B.G. yard. If the speed on the main curve is restricted to 54.53

    kmph, determine the speed restriction on the branch line. Assume permissible cant

    deficiency as7.5 cm.

    (b) What do you understand by cant deficiency? If an 8 curve track diverges from

    main curve of 5 in an opposite direction in the layout of a B.G. yard, calculate thesuper elevation and the speed on branch line, if the maximum speed permitted on

    the main line is 45 kmph.

    Solution

    (a) Radius of the main line curve

    m5.4374

    1750

    Equilibrium cant for a speed of 54.53 kmph

    RGVe27.1

    2

    24

  • 5/28/2018 railway track sleepers

    25/31

    5.43727.1

    53.5453.54676.1

    x

    xx

    = 8.97cm

    Actual super elevation on the main line track = Equilibrium cant - cant deficiency

    = 8.97-7.5 = 1.47 cm

    Max. Negative cant on the branch line = -1.47cmTheoretical super elevation on the branch line = Negative cant + cant deficiency

    = -1.47+7.5= 6.03 cm

    Restricted speed on thr branch line may be obtained from the equation

    R

    GV

    27.103.6

    2

    676.1

    35027.103.62 xxV

    =1599.2452V = 39.99 say 40kmph. Ans.

    (b)The cant deficiency may be defined as the difference between the cant necessary forthe maximum permissible speed on a curve and the actual cant provided. Higher cant

    deficiency causes more unbalanced centrifugal force and discomfort to thepassengers.

    G = 1.676 cm

    V = 45 kmph

    mR5

    1750

    Equilibrium cant on main line curve

    R

    GVe

    27.1

    2

    cmx

    xxx635.7

    175027.1

    54545676.1

    Assume a permissible cant deficiency on B.G. track = 7.6 cm

    Actual cant to be provided on main track = Equilibrium cant-deficiency= 7.635-7.600 = 0.035 cm

    Negative cant on branch line =-0.035 cm. Ans.

    Theoretical cant on the branch line track = negative cant + cant deficiency= -0.035 + 7.600 = 7.565 cm.

    Let V be the restricted speed on the branch line

    masRx

    xxV

    8

    1750

    175027.1

    8676.1565.7

    2

    9686.12538676.1

    175027.1565.42

    x

    xxV

    Vmaxon the branch line = 35.4 kmph. Ans.

    25. (a) Explain why super elevation is necessary on a curve alignment.

    (b) Explain briefly types of classification of horizontal curves.

    25

  • 5/28/2018 railway track sleepers

    26/31

    Solution

    (a) Super ElevationWhen a vehicle negotiates a curve, it is subjected to a constant radial acceleraton

    which produces centrifugal force acting horizontally at the centre of gravity of the

    vehicle, radially away from the centre of the curve. In order to counteract this force,

    the outer rail of the track is raised slightly higher than the inner rail. The difference inelevation between the outer rail and inner rail is called super elevation or cant.

    (b) Classification of Horizontal Curves

    Horizontal curves are classified as under:(1)Simple curves(2)Compound curves(3)Reverse curves(4)Transition curves.

    (1)Simple curves: The horizontal curve which consists of a single are of a circle, is calleda simple curve of simple circular curve. Simple circular curves are designated either

    by their degree of radius. They are inserted between two straights or between two

    transition curves.(2)Compound curves: The horizontal curve which consists of two or more arcs of

    different circles with different radii, having different centers on the same side of the

    common tangent and bending in the same direction, is called a compound curve.

    (3)Reverse curves: The horizontal curve, which consists of two arcs of different circlesof same or different radii, bending in opposite directions with a common tangent at

    the junction, is called a reverse curve.(4)Transition curves: The horizontal curve of varying radii introduced between a straight

    and a circular curve, is called a transition curve.A transition curves is also known as curve of easement. The radius of a transition

    curve varies from the infinity at its beginning to a definite minimum value at the junctionof the circular curve.

    CHAPTER 9

    POINTS AND CROSSINGS

    26. Write short notes in the followings:

    i. Left hand and right hand turn outsii. Theoretical nose of crossing and Actual nose of crossing

    iii. Splice rails and Wing railsiv. Point rails and Stock railsv. Tongue rails and Stretcher bar

    Solution

    i. Left hand turnout:The turnout which diverts the trains to the left, is called a left hand

    turnout.Right hand turnout:The turn out which diverts the trains to the right, is called a right handturn out.ii. Theoretical nose of crossing (T.N.C). the point of intersection of the gauge faces of thepoint rail and splice rail of a crossing, is called the theoretical nose of crossing. It is slightly

    away from the actual nose of the crossing.Actual nose of crossing (A.N.C.). The ends of the point rail in the gap of the crossing is

    called actual nose of the crossing

    26

  • 5/28/2018 railway track sleepers

    27/31

    iii. Splice rail.The rail of the V-shaped portion of the crossing I,e frog, which ends a little

    behind the nose of crossing is called splice rail.Wing rail. The two bent up rails of the crossing which are connected to the ends of the

    crossing lead rails (one straight and one curve rail) are called the wing rails.iv. Point rail.The rail of the V-shaped portion of the crossing i.e. frog, which ends at the

    nose of crossing, is called point rail.Stock rails.The rails of the main line track against which tongue rails snugly fit, are calledstock rails.v. Tongue rails.The tapered rails whose thicker ends known as heel are fixed to the maintrack an thinner end known as toe of the switch to obtain a snugfit with the respective stock

    rails, are called tongue rails, switch rails or point rails. By moving the tongue rails, the

    flanged wheels of the trains are diverted from one track to the other.Stretcher bars.Two or three bars which are used to connect the ends of the tongue rails at

    the toe to ensure the movement of both the tongues through the same distance, are calledstretcher bars.

    27.(a) On a straight B.G. track, a turnout takes off as an angle of 6 42 35Angle of switch = 1 34 27

    Length of switch rail = 4.37 m

    Heel divergence = 11.43 cm

    Length of straight arm = 0.85 m.

    Determine the radius and the crossing lead.

    (b) A 1 in 12 turn out is to be provided on a B>G> straight track, calculate (i) radius

    of the curve lead rail (ii) lead distance, and (iii) over all length of the turn out.

    Data given:

    Heel divergence = 133 mm

    Actual length of switch rail = 6001 mm

    Theoretical length of switch rail = 6743 mm

    Distance between toe of crossing and theoretical nose of crossing = 2415 mm

    Distance between toe of crossing and theoretical nose of crossing = 1498 mm

    Distance between theoretical nose of crossing and heel of crossing = 3810 mm

    Solution

    (a) As the length of straight arm (h) is given, the second method of design will be adopted

    Given: G = 1.676m

    d = 0.1143 mh = 0.85 m

    = 6 42 35= 1 34 27

    coscos

    sin

    hdG

    Ro

    m

    Ro

    96.225

    "35'426cos"27'341cos

    "35'426sin85.01143.0676.1

    27

  • 5/28/2018 railway track sleepers

    28/31

    .12.225

    2

    676.196.225

    20

    Ansm

    GRR

    .08.21

    "35'426cos85.02

    "27'341"35'426cot)"35'426sin85.01143.0676.1(

    cos2

    cot)sin(

    Ansm

    hhdGleadincross

    (b) From the given data, it is seen that the design is to be done by Method No.2

    For 1 in 12 turnout "49'454

    Let be the angle of switch

    0197.06743

    133sin

    railswitchoflengthltheoretica

    enceheeldiverg

    = 1 7 49

    09.412

    "49'454cos"49'71cos

    "49'454sin415.2133.0676.1

    coscos

    sin

    hdGRo

    R=412.09-0.838=411.252m Ans.

    Or

    Crossing lead = (G-d-h sin )cot + /2+h cos

    L=1.343cot 2 56 49+2.415cot 4 45 49

    =28.495m Ans.

    Over distance = Distance between heel of crossing and T.N.C. + lead distance + actual length

    of switch rail + distance between actual toe of switch and end of stock rail.

    = 3.810 + 28.495 + 6.001 + 4.498

    Over length = 39.804 m. Ans.

    CHAPTER 10

    TRACK MAINTENANCE

    28. Describe the followings:

    i. Necessity of track maintenanceii. Essentials of good track maintenance

    iii. Advantages of proper track maintenance

    28

  • 5/28/2018 railway track sleepers

    29/31

    Solution

    i. Necessity of Track Maintenance

    The track maintenance is carried out for the following purposes:

    (1)As a newly laid railway track settles slowly under moving train loads, themaintenance gangs are employed to bring the embankment to the proper formation

    level.(2)Due to constant movement of heavy and fast moving trains, the packing under

    sleepers gets loose and thus the geometry of the track gets disturbed. The gauge,

    alignment longitudinal and cross levels also get affected adversely, Hence, the

    maintenance gangs are required regularly to rectify these defects as and when these

    occur.

    (3)Due to vibrations and impact of the fast moving trains, railway track fittings get looseand a heavy wear and tear of track occurs. This necessitates regular inspection and

    maintenance of the track.

    (4)Maintenance is also required to replace the track and its components as and whenthese wear and tear due to natural weathering agents such as sun, sand and rain water.

    ii. Essentials of Good Track MaintenanceA well maintained track should have the following characteristics:

    (1)The correct gauge is within specified limits.(2)Longitudinal levels are uniform.(3)The cross levels are same except on curves where difference in cross levels is equal

    to the desired super-elevation.

    (4)Along straights, the alignment is perfectly linear.(5)There is a sufficient quantity of ballast bed.(6)The sleepers are well packed.(7)The formation is well maintained with good track drainage for disposal of rain water.(8)The components of all fittings are in the good working condition. Defective or badly

    worn and torn components are replaced at an earliest opportunity.

    iii. Advantages of Proper Track Maintenance

    The advantages of a well maintained track are as under:

    (1)A well maintained track provides safe and comfortable journey to passengers. If thetrack is not maintained properly, there will e discomfort to the passengers and some

    times, there may be a derailment of vehicles, causing accidents and consequently loss

    of lives and property.

    (2)Proper maintenance of track increases the life of track as well as that of the rollingstock.

    (3)Good track maintenance helps in reducing the fuel consumption and cost of operation.(4)Maintenance of track fittings at proper time avoids the loss of the items and thus, itaffords considerably economy.

    (5)Track maintenance, if ignored for a long time may result in heavy track renewals,costing a huge expenditure.

    29. Calculate the necessary data for setting out a semi permanent diversion 20 m

    away from the B.G. track.

    Assume: radius of the curves = 440 m

    Gradient along diversion = 1 in 100

    Straight proportion of diversion = 50 m

    Straight length between reverse curve = 30.5 m.

    29

  • 5/28/2018 railway track sleepers

    30/31

    Solution

    Given data:

    d = 20m; R = 440 m

    c = 30.5 m; S = 50 m

    Calculation of the length L,

    24 22 SdcRdL

    = 214.02m

    Total length of diversion along main track = 2x214.02 = 428.04 m. Ans.

    Calculation of tangent length

    .09.40

    2

    Ansm

    cS

    L

    Rdt

    Total diversion length along curve = 8t+2c+s = 8x40.09+2x30.05+50 = 431.72 m Ans.

    Length of offset, O = (formation width +gauge)/2

    m888.32

    676.110.6

    Length of diversion on the existing track formation

    ..49.58440888.322 AnsmxxORa

    Length of diversion along which grade is to be provided

    = (4t + c-a) = 4 x 40.09 + 30.5-58.49

    = 160.36 + 30.5-5849 = 132.37 m

    Grade permitted is 1 in 100, i.e. 1%

    Compensation for 1750/440 degree curve say 4

    = 4 x 0.04 = 0.16%Compensated grade = 1-0.16 = 0.84%

    Maximum lowering of bank

    = (132.37 x 0.84)/100 = 1.11 m. Ans.

    30. Design the layout of a 2 m high BG semi permanent diversion for rebuilding a 4 x

    6.1 m bridge on 4 m high line track. Adopt economical specifications.

    Solution

    Assumptions

    Radius of curves = 440 m (approximately 4 curve)Straight length between reverse curves = 30.5 m

    Gradient = 1%

    Grade compensation = 0.04% degree of curve

    Given:

    High of main bank = 4 m

    High of diversion bank = 2m

    Calculations:

    Difference in high of bank = 4-2 = 2 m

    Minimum value of S = 30.5 + 4 x 6.1 + 30.5

    = 85.4 say 86 m

    minimum distance, d = 2x4 +2 x 2 + 6.10= 18.10 m

    30

  • 5/28/2018 railway track sleepers

    31/31

    Value of L

    24 22

    SdcRd

    mxx 2.2232

    86

    )1.18()5.30(1.18440422

    2L = 446.4 m.

    Value of tangent length

    .80.377978.375.30432.223

    1.18440

    2

    msayx

    cS

    L

    Rdt

    Value of offset O1

    .888.32

    676.110.6

    2m

    gaugeidthformationw

    Value of a

    mxxRO 49.58440888.322 1

    Length of diversion where grade to be provided on either side =4t+c-a=4x37.8+30.5-58.49

    =123.21 m

    compensated grade

    = 1- (0.04 x 4)%

    = 0.84 %

    Amount of lowering the level of diversion

    mormx

    1013.1100

    84.021.123

    Difference of 2-1 = 1 m is to be adjusted in the portion of diversion length parallel to themain track, i.e.

    Length required cover 1 m height at 1 % grade, i.e.

    = 1 x 100 = 100 m

    Total diversion length along the curve

    = 8t +2c +S +2 x 100

    = 8 +37.8 +2 x 30.5 +86 x 200

    = 302.4 +61.0 +86 +200 = 649.4 m

    And, final revised length of diversion along the track

    = 2L +2 x 100 = 446.4 + 200

    2L = 646.4 m Ans.

    31

    BY

    WYTU

    [email protected]

    01-685277/685266

    09-5006311