Nationwide Review of Graduated Driver Licensing

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Nationwide Review of Graduated Driver Licensing
Research conducted by Johns Hopkins Bloomberg
School of Public Health
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AAA Foundation for Traffic Safety

• Established in 1947
• 501 (c)(3) Not-For-Profit
• Research affiliate of AAA/CAA
• North American Focus

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Mission

• Identify traffic safety problems
• Foster research that seeks solutions
• Disseminate information and educational materials

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Funded through the generosity of and its
members
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Published February 2007 Prepared by Johns
Hopkins Bloomberg School of Public
Health Available online at www.aaafoundation.
org
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The teen crash problem

• Motor vehicle crashes are the 1 cause of death
  for teens
• Roughly 1,000 16-year-old drivers involved in
  fatal crashes each year
• 400 16-year-old drivers killed annually
• Nearly 2 other fatalities per teen driver
  fatality
• Passengers of teen
• Drivers and passengers in other vehicles
• Pedestrians, bicyclists, etc.
• Nearly 100,000 involved in injury crashes
  (10,000 resulting in incapacitating injuries)

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Graduated Driver Licensing (GDL)

• Typical three-stage GDL program involves
• Learner stage all driving must be supervised by
  adult (usually parent)
• Intermediate (or Provisional) stage allows
  unsupervised driving but only under certain
  conditions (e.g., during the day, no passengers)
• Full License requires successful completion of
  first two stages

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Purpose of study

• Analyze overall (nationwide) crash reduction of
  having any three-stage GDL program
• Distinguish between effectiveness of the most
  comprehensive programs and relatively weaker
  programs
• Assess how much better we could be doing if all
  states had the most comprehensive programs

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The Study - Data

• GDL Laws (1994-2004, all states, from AAA, IIHS,
  and individual states)
• Fatal crashes (1994-2004, 43 states, from
  National Highway Traffic Safety Administration)
• Injury Crashes (1994-2003, 35 states, obtained
  with permission from individual states)
• Population estimates (all states and years
  studied, from U.S. Census Bureau) states)

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The Study Analysis

• State-quarter crash rates and laws in one state
  for one quarter-year
• e.g., Alabamas crash rates and Alabamas laws
  between January 1, 2000 and March 31, 2000 is
  one state-state quarter
• Combined state-quarters with the same laws to
  estimate overall impact of laws (1 national
  study, not separate study in each state)

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The Study Analysis

• Statistical methods (negative binomial
  regression) to control for differences unrelated
  to GDL (state-to-state differences, time trends,
  seasonal variation)
• Also looked at crash rates of older drivers (ages
  20-24, 25-29, 30-54) these should not have been
  impacted by GDL

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Overall impact of 3-stage GDL programs

• Rate of fatal crashes of 16-year-olds reduced by
  11 (per capita) in states with 3-stage GDL
  programs
• Rate of injury crashes reduced by 19
• Reductions much smaller (and not statistically
  significant) for older drivers
• Results adjusted for state-to-state differences,
  seasonal differences, and time trends
• These results include strong and weak programs,
  so not representative of effectiveness of the
  best programs

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Percentage difference in crash rates in relation
driver age and presence of 3-stage GDL program
Columns represent estimated differences in crash
rates, vertical lines represent 95 confidence
intervals (Negative means crash rate lower with
3-state GDL program than without)
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Program comprehensiveness

• Studied seven key components, grouped states by
  how many they had
• Minimum age of 16 for learners permit
• Requires at least 6 months with learners permit
  before intermediate or full license
• Requires at least 30 hours supervised driving
  during learner stage
• Minimum age of 16 years 6 months for intermediate
  license
• No driving allowed after 10 PM during
  intermediate stage
• No more than 1 passenger allowed during
  intermediate stage
• Minimum age of 17 for full license

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Program comprehensiveness

• No state had more than 5 of the 7 during the
  study
• Fatal crashes of 16-year-olds reduced by 38,
  injury crashes by 40, in states with 5 of the 7
  components
• Reductions of 21 (fatal crashes) and 36 (injury
  crashes) in states with 4 of 7
• Smaller reductions with fewer components

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Percentage difference in fatal crash rates in
relation to driver age and number of program
components
Columns represent estimated differences in crash
rates, vertical lines represent 95 confidence
intervals (Negative means crash rate lower with
number of components shown than with none)
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Percentage difference in injury crash rates in
relation to driver age and number of program
components
Columns represent estimated differences in crash
rates, vertical lines represent 95 confidence
intervals (Negative means crash rate lower with
number of components shown than with none)
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Recommendations

• States that do not yet have 3-stage GDL programs
  (learner permit, intermediate license, full
  license) should adopt 3-stage programs
• associated with 11 reduction in fatal crashes,
  19 reduction in injury crashes of 16-year-olds
• States should move toward implementing a full
  complement of meaningful GDL program components
• Programs with 5 components have much greater
  impact than average 3-stage programs

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Limitations of the Study

• GDL components studied were compromise between
  existing recommendations (from AAA, IIHS, and
  others) and statistical requirementsthis study
  does not prove that they are optimal
• Statistical model couldnt control for
  everything, some other factors could have
  influenced results
• Cant tell how apparently effective programs work
  (safer driving? less driving? both? other
  ways?)
• Didnt look at older teens

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• For more information,
• please go to
• www.aaafoundation.org

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The AAA Foundation for Traffic Safety is a
501(c)(3) public charity located in Washington,
DC that is dedicated to saving lives and reducing
injuries. It is supported by donations from
AAA/CAA Clubs, AAA/CAA members, and other
organizations associated with AAA/CAA.