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First Annual Virginia Distracted Driving Summit

David S. ZubyChief Research Officer

September 19, 2013Richmond, Virginia

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• 1979 – Indiana “Tri-Level Study” estimated “driver error” to be proximate cause of 9 out of 10 crashes

• Personal reports from drivers reveal a variety of distracting events preceding crashes

– Changing audio tapes/CDs

– Eating/drinking

– Children, bugs, animals in vehicle

– Reading, shaving, and applying makeup

• 2005-07 in-depth crash study estimated driver-related factors associated with 93 percent of crashes

Driver distraction is not a recent phenomenon

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3 most common distractionsEstimated prevalence

Stutts et al. (2005):

Coded sample of recorded driving

Sayer et al. (2010):

Sampled clips from IVBSS FOT

Passenger conversation

(15%)

Passenger conversation

(17%)

Internal distraction (e.g., adjusting HVAC, reaching for objects)

(4%)

Cellphone conversation

(6%)

Eating/drinking

(3%)

Grooming

(5%)

Not distracted

(31% when moving)

Not distracted

(59%)

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Experimental studies show hand-held and hands-free phone tasks degrade simulated or test-track driving performance

• Strengths

– Isolate effects of cellphone tasks (e.g., manual dialing, conversation type) by controlling for potential confounding variables (e.g., demand of driving task)

• Limitations

–Small volunteer samples

–Driving and distraction tasks paced by experimenters, not drivers, and may be unrealistic

–Unknown whether findings pertain to drivers using phones in their own vehicles because of learning effects, self-regulation, or other factors

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Naturalistic driving studies found dialing and texting, but not conversation, increase risk of crash surrogates• Strengths

– Drivers using own phones in own vehicles can be observed for an extended period of time

– Hand-held phone use can be verified at time of safety-relevant events and for control periods of driving

• Limitations

– Small samples of crashes preclude estimating crash risk and necessitate use of crash surrogates (e.g., near-crash, traffic conflicts)

– Documentation of hands-free phone use less reliable without phone records

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Studies verifying crash-involved drivers’ phone use found increased risk with hand-held and hands-free phones

• Strengths

– Large samples of real-world crashes

– Cellphone billing records used to verify phone use at time of crash and during control driving periods

• Limitations

– Reasons for talking on phone may not be independent of crash risk

– Drivers with higher crash risk may be affected by phone use differently than lower risk drivers

– Documenting driving in crash and control periods dependent on drivers’ recollections

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Many drivers use cellphones National observational surveys, NHTSA, 2000-11

2000 2002 2004 2005 2006 2007 2008 2009 2010 20110

2

4

6

8

10

12

estimated total phone use

observed hand-held phone use

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All police-reported crashes per million miles traveledBy calendar year

1988

89 90 91 92 93 94 95 96 97 98 99 2000

01 02 03 04 05 06 07 08 09 10 110

1

2

3

4

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Actual hand-held phone use vs. use that would have been expected without hand-held cellphone bansPercent phone use, April 2009

0

2

4

6

8

actual

expected

The effects of bans on drivers’ hand-held

phone use differ considerably, but bans can result in long-term

reductions in drivers’ hand-held phone use.

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Estimated effect of hand-held cellphone bansCollision claim frequencies for new vehicles

estimated effect vs. control states P-value

California -1% 0.2635

Connecticut +4% 0.0317

District of Columbia -5% 0.1753

New York +3% 0.0052

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Can technology that blocks cellphone calls and texting help?

• Several technologies block incoming and outgoing phone calls and text messages when the car is moving

– Examples include Aegis Mobility, Trinity Noble, Zoomsafer, and Key2SafeDriving

• Systems vary in sophistication and features

– Most allow passengers to use phones

– All allow calls to emergency services

• Most use phone’s GPS to detect when it is traveling above a specific speed threshold

• Effects on driving performance or crashes unclear

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We may be able to reduce the problem of distraction without fully understanding it

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• Front crash prevention systems are working

• Adaptive headlights are working

• Benefits of other systems are less clear:

– Lane departure warning

– Blind spot warning

– Rearview cameras

– Parking proximity sensors

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The New Yorker, April 23, 2007