Newswise — A new study from The Children’s Hospital of Philadelphia (CHOP) 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 (i.e., probationary) teen drivers. The study, which linked New Jersey’s licensing and crash record databases to measure effects of the requirement, was published today 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 US. CHOP researchers are the first in any country to evaluate the long-term changes in crash rates after a decal provision went into effect.

CHOP researchers 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. They found that, 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 after accounting for age, gender, calendar month, unleaded gas price, and crash trends among older licensed drivers. 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.

“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,” says lead author Allison Curry, PhD, MPH, director of Epidemiology and Biostatistics at the Center for Injury Research and Prevention at CHOP. “There is definitely more we need to learn, in particular with respect to the specific mechanisms by which the decals reduced crashes. The end result, however, is that many fewer teens crashed.”

New Jersey already has one of the most comprehensive GDL programs in the country and also one of the lowest teen driver crash fatality rates. Even so, New Jersey was able to achieve additional reductions in crashes with a decal provision as part of its GDL. Researchers at CHOP suggest other states could potentially further boost the effect of comprehensive GDL programs by adding a decal requirement and extending the age requirement for GDL systems to age 21. They should look to New Jersey’s experience to help shape their strategy as well and use these evidence-based fact sheets to start a conversation with policymakers:

• Boost Your State GDL: Extend Age Requirement

• Boost Your State GDL: Enact A Decal Provision

Funding for the study was provided by State Farm Mutual Automobile Insurance Company (State Farm®). The views and recommendations in this publication do not necessarily reflect those of State Farm.

About the Center for Injury Research and Prevention at The Children’s Hospital of Philadelphia®The Center for Injury Research and Prevention at The Children's Hospital of Philadelphia was established in 1998 to advance the safety and health of children, adolescents, and young adults through comprehensive research that encompasses before-the-injury prevention to after-the-injury healing. The Center‘s multidisciplinary research team, with expertise in Behavioral Sciences; Clinical Care; Engineering; Epidemiology and Biostatistics; Human Factors; Violence Prevention; Digital Health Evaluation; Public Health; and Communications, translates rigorous scientific research into practical tools and guidelines for families, professionals, and policymakers to ensure research results extend to the real world. For more information on the Center and its research initiatives, visit injury.research.chop.edu.