Nationwide Review of Graduated Driver Licensing Research conducted by Johns Hopkins Bloomberg School of Public Health AAA Foundation for Traffic Safety • Established in 1947 • 501 (c)(3) Not-For-Profit • Research affiliate of AAA/CAA • North American Focus Mission • Identify traffic safety problems • Foster research that seeks solutions • Disseminate information and educational materials Funded through the generosity of and its members Published February 2007 Prepared by: Johns Hopkins Bloomberg School of Public Health Available online at: www.aaafoundation.org 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) 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 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 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) The Study – Analysis • State-quarter: crash rates and laws in one state for one quarter-year – e.g., “Alabama’s crash rates and Alabama’s 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) 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 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 Percentage difference in crash rates in relation driver age and presence of 3-stage GDL program Fatal Crashes Injury Crashes 10% 0% -10% -11% -20% -19% Age 16 -30% Age 20-24 Age 25-29 -40% Age 30-54 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) Program comprehensiveness • Studied seven key components, grouped states by how many they had 1. Minimum age of 16 for learner’s permit 2. Requires at least 6 months with learner’s permit before intermediate or full license 3. Requires at least 30 hours supervised driving during learner stage 4. Minimum age of 16 years 6 months for intermediate license 5. No driving allowed after 10 PM during intermediate stage 6. No more than 1 passenger allowed during intermediate stage 7. Minimum age of 17 for full license 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 Percentage difference in fatal crash rates in relation to driver age and number of program components One Two Three Four Five Component Components Components Components Components 30% 0% -4% -10% -10% -21% -30% Age 16 Age 20-24 Age 25-29 -60% Age 30-54 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) -38% Percentage difference in injury crash rates in relation to driver age and number of program components One Component Two Three Four Five Components Components Components Components 30% +3% 0% -13% -30% Age 16 Age 20-24 Age 25-29 -60% Age 30-54 -16% 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) -36% -40% 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 Limitations of the Study • GDL components studied were compromise between existing recommendations (from AAA, IIHS, and others) and statistical requirements—this study does not “prove” that they are optimal • Statistical model couldn’t control for everything, some other factors could have influenced results • Can’t tell how apparently effective programs work (safer driving? less driving? both? other ways?) • Didn’t look at older teens For more information, please go to: www.aaafoundation.org 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.