A new study has found 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, conducted by the Children’s Hospital of Philadelphia, was published today in the American Journal of Preventive Medicine.
The study found that crash involvement of an estimated 3,197 intermediate drivers in New Jersey 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, according to the study. 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., the study said. Currently New Jersey is the only state with a measure requiring those younger than 21 without full-privilege licenses to display a decal on their vehicle identifying them as new drivers.
The Children’s Hospital of Philadelphia said its researchers are the first in any country to evaluate the long-term changes in crash rates after a decal provision went into effect.
The 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.
The study said 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 decline in either group.
A previous study by the Children’s Hospital of Philadelphia on the decal’s first year of implementation found a 14 percent rise 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,” said Allison Curry, lead author of the report and director of Epidemiology and Biostatistics at the Center for Injury Research and Prevention at the Children’s Hospital of Philadelphia.
“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,” said Curry.
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, according to the study.
Researchers at the Children’s Hospital of Philadelphia 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.
Funding for the study was provided by State Farm Mutual Automobile Insurance Co.
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.
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