UNC Study: Graduated Licensing Program Reduces Teen Crashes
Posted October 2, 2001
CHAPEL HILL, NC — The number of crashes involving 16-year-old drivers in North Carolina decreased dramatically from 1996-97 to 1999, including a 57 percent drop in fatal crashes, according to a University of North Carolina Highway Safety Research Center study.
The study, to be published in the Oct. 3 issue of
The Journal of the American Medical Association
, examined the initial effects of graduated driver licensing, or GDL, on crashes involving 16-year-old North Carolina drivers.
Dr. Robert D. Foss and colleagues at the center compared crash rates from 1996-97 - before 16-year-olds were licensed under the GDL system - and crash rates from 1999, when the new system was in place. To control for other factors possibly influencing crashes, the authors compared changes among 16-year-old drivers with those ages 25 to 54. They also studied crashes per licensed driver to rule out the possibility that a decrease in the number of licensed drivers might explain the drop in crashes.
North Carolina instituted the GDL system on Dec. 1, 1997, requiring young beginning drivers to pass through two restricted driving periods before they receive their unrestricted licenses. In level 1, beginning drivers who are at least 15 years of age (and younger than age 18) may drive only with the supervision of a designated adult. At the end of level 1, which lasts at least 12 months, drivers with no traffic violations in the last six months and who have passed a road test may move to level 2. At this stage, unsupervised driving is permitted between 5 a.m. and 9 p.m. Driving after 9 p.m. may be done only with the adult supervisor in the vehicle. After at least six continuous months with no traffic violations at level 2, drivers graduate to a full, unrestricted license (level 3).
Foss, lead author of the study, said that the results, though remarkable, were not surprising to him and fellow investigators Dr. John R. Feaganes and Eric A. Rodgman.
"Because GDL is based on a firm understanding of human behavior developed through decades of social and behavioral science research, it was highly likely to have the effect it was designed to produce," Foss said. "These study findings strongly affirm that GDL is tremendously successful."
Among the study's findings comparing 1996 (pre-GDL) crashes with 1999 (post-GDL), as reported in the JAMA article, are the following:
"Crash rates declined sharply for all levels of severity among 16-year-old drivers after the GDL program was implemented," the authors wrote.
Motor vehicle crashes are the most common cause of death among teenagers in the United States, according to the National Center for Injury Prevention and Control. The crash risk is highest among the youngest drivers.
Inexperience and impulse actions contribute to the greater crash propensity among beginning drivers. Since 1997, 34 states have enacted GDL systems designed to reduce crash rates among novice drivers.
Related UNC Highway Safety Research Center findings were that fatal and serious injury crashes were between 18 percent and 21 percent more likely in the more rural counties than in the most urban North Carolina counties during 1999, Foss said. The new study found that crashes among 16-year-old drivers declined similarly regardless of degree of county urbanization - good news for those rural counties where crash risks are higher.
Preliminary findings from another study being conducted at the UNC Highway Safety Research center indicate that parents and teens alike endorse GDL. In telephone interviews with 600 families, more than 95 percent of North Carolina parents either "highly approved" or "somewhat approved" of GDL, and 80 percent of the state's teens gave the same assessment. In an issue of interest to states still considering a GDL program, the study found that parents and teens from the most rural areas support GDL just as strongly as those from urban and suburban locations.
Study authors said that in consideration of the clear benefits of GDL demonstrated in North Carolina and elsewhere, doctors in states without GDL systems, or where there is a relatively weak GDL program, should consider advising both their teen patients and parents of teens to follow the principles of a model GDL program.
"This should include at least six months during which the teen drives extensively with a responsible adult supervisor, followed by prohibitions on unsupervised nighttime driving and transporting of passengers, until the teen has accumulated at least six months of additional driving experience without an adult supervisor," the report stated.
The UNC study was supported in part by the National Highway Traffic Safety Administration and the North Carolina Governor's Highway Safety Program. Some preliminary study results were announced in mid-2000.