Research In Action

Graduated Driver Licensing (GDL) is the cornerstone of public policy to reduce the burden of young driver crashes. Further reductions in teen crash rates will rely on strengthening specific GDL provisions, as well as greater enforcement of and compliance with these provisions.

In May 2010, New Jersey became the first state in the country to require vehicle identifiers via a decal provision for young drivers with learner’s permits and intermediate licenses. The provision is designed to facilitate the ability of police to enforce GDL provisions, such as limits on nighttime driving and passengers, and to promote teen compliance with these provisions and other important traffic safety laws.

Although decal provisions have existed in international jurisdictions for decades, before New Jersey’s law, they hadn’t been evaluated for effectiveness. In a study published today in Injury Prevention, we evaluated the effect of the provision on citation and crash rates among 17- to 20-year-old drivers with learner’s permits in New Jersey. In contrast to our previous research that found a significant decrease in the crash rates of drivers with intermediate licenses after the decal provision, the GDL decal provision was not associated with a change in citation or crash rates among NJ drivers with learner’s permits.

Requiring Decals Doesn’t Lower Crash Rates during Learner Period

We believe that this may be because drivers with a learner's permit already have high compliance with passenger and night restrictions and very low crash rates because they drive with a supervising adult in the vehicle. Therefore there’s less room for interventions to have a substantial impact on crash rates. On the other hand, it is possible that requiring decal use during the permit period may help establish safe driving behaviors and/or contribute to compliance with the decal and other GDL provisions in the intermediate license phase. The extent to which the decal provision influences these behaviors is currently unknown.

In the meantime, several US states have or are currently developing legislation related to decal provisions. Decals were also a recommended provision in a recently-proposed framework from the Traffic Injury Research Foundation, part of the National Safety Council. This exhaustive report, written by an expert panel, aims to help states reinvigorate their GDL programs with the latest evidence.

We’ve also created an educational fact sheet to share with state legislators interested in considering a decal provision to strengthen their GDL programs.