Crash rates for Michigans 16-year-old drivers have been cut by a quarter, due in large part to the states new driver licensing program, say U-M researchers in a new study that appears in the Oct. 3 issue of the Journal of the American Medical Association.
Following the 1997 implementation of Michigans three-stage graduated driver licensing (GDL) program for new drivers, 16yearolds were involved in fewer crashes in 1999 (16,500) than in 1996 (22,625). The overall crash rate for these drivers fell from 154 (per 1,000 population) to 111a 28 percent decline. After adjusting for a population-wide downward trend for crash involvement, the crash rate for these new drivers was still down 25 percent.
Unintentional injury from motor vehicle crashes is the leading cause of death among U.S. teen-agers, says Jean T. Shope, senior research scientist at the U-M Transportation Research Institute and the School of Public Healths Department of Health Behavior and Health Education. Yet, driver licensure in the United States has been allowed at young ages and after only minimal classroom education and behind-the-wheel training.
Michigans GDL system for licensing young drivers, however, is an extremely promising approach to reducing injury from motor vehicle crashes among teen-agers.
Using crash data from the Michigan State Police, Shope and colleagues Lisa J. Molnar, Michael R. Elliott and Patricia F. Waller also found significant reductions for injury crashes; day, evening and night crashes; and single-vehicle and multi-vehicle crashes. Although small in numbers, fatal crashes declined from 54 to 37 and alcohol-related crashes continued at a low rate.
After accounting for general population trends, the researchers say that injury crashes were down 24 percent. Night (midnight5 a.m.) crashes registered the greatest reduction in crash risk, decreasing 53 percent, while day (5 a.m.9 p.m.) crashes were down 24 percent and evening (9 p.m.midnight) crashes declined 21 percent.
The sharp drop in risk of night crash involvement relative to day or evening crash involvement suggests that the night driving restriction during the intermediate stage of licensure has been very effective, Shope says. On the other hand, the drop in evening crashes is less than the drop for overall crashes, suggesting that a driving restriction that includes at least some evening hours might enhance GDLs effect further.
The study also found that single-vehicle crashes declined 29 percent, while multi-vehicle crashes decreased 23 percent.
These results are among the first in the nation to evaluate a complete changeover among teen novice drivers into a comprehensive GDL system that includes a two-phase driver education requirement and also requires certification by a responsible adult that a young driver has received extended supervised practice, Shope says.
While evaluation over the longer term is needed to see if the crash reductions are maintained as new cohorts of teen drivers enter and progress through the system, these early results in preventing crashes among young drivers are impressive.
The study was funded by the National Highway Traffic Safety Administration.