A new study from the Center for Injury Research and Prevention (CIRP) provides valuable evidence that New Jersey’s Graduated Driver Licensing (GDL) decal provision is associated with a sustained two-year decline in crash rates among intermediate teen drivers. The study, which linked New Jersey’s licensing and crash record databases to measure effects of the requirement, was published recently in the American Journal of Preventive Medicine. Crash involvement of an estimated 3,197 intermediate drivers was prevented in the first two years after the decal’s implementation.
In May 2010, New Jersey implemented Kyleigh’s Law, requiring all youth 16 to 20 years of age holding a learner’s permit or intermediate license to display a reflective decal on the front and back license plates of vehicles they are operating. On any given day there are more than 170,000 intermediate drivers on New Jersey’s roadways. The decal was intended to facilitate police enforcement of GDL restrictions and, ultimately, reduce teen crash rates.
While many other countries have had decals for decades, New Jersey is the first state to implement them in the U.S. And CHOP researchers are the first in any country to evaluate the long-term changes in crash rates after a decal provision went into effect.
“Decal provisions now have the support of science. The provision may encourage safer driving behaviors, both among teens and other drivers sharing the road with them,” said the study’s lead author, Allison Curry, PhD, MPH, CIRP’s director of Epidemiology and Biostatistics.
Dr. Curry and the CIRP team — including biostatistician Michael R. Elliott, PhD, and Dennis Durbin, MD, MSCE, director of CHOP Research’s Office of Clinical and Translational Research — linked New Jersey’s licensing and motor vehicle crash databases from January 2006 through June 2012 to compare monthly rates of police-reported crashes for intermediate drivers in the four years before the decal’s implementation and in the two years after. After accounting for age, gender, and other criteria, the investigators found in the first two years after the new decal requirement took effect the crash rate for young intermediate drivers declined 9.5 percent, as compared to the previous four years before decal implementation.
More dramatic effects were observed for single-vehicle crashes involving older intermediate drivers, with rates decreasing 13 percent per year for 18-year-olds and nearly 17 percent for 19-year-olds. In the previous four years before the decal was put into practice, the rate of single-vehicle crashes did not significantly decrease in either group.
A previous CHOP study on the decal’s first year of implementation found a 14 percent increase in the rate of GDL-related citations issued to intermediate drivers, but the increase seemed to be concentrated in the few months after implementation.
“There is definitely more we need to learn, in particular with respect to the specific mechanisms by which the decals reduced crashes,” noted Dr. Curry. “The end result, however, is that many fewer teens crashed.”
To learn more about the Center for Injury Research and Prevention work on teen driver safety and other topics, visit the CIRP website.