Effectiveness of graduated driver licensing in reducing motor vehicle crashes.

Objective: To determine whether graduated driver licensing (GDL) systems and nighttime curfews reduce motor vehicle crashes, fatalities, or injuries among young drivers.

Methods: We used Cochrane Collaboration search strategies to locate studies of graduated licensing or night driving restrictions. Studies were selected if they examined the effects of either (1) a comprehensive graduated driver licensing system including well-integrated components, or (2) nighttime driving restrictions/curfews that could affect young persons' nighttime driving, on a clearly defined crash or injury outcome. Seven studies met inclusion criteria.

Results: Two independent studies of the New Zealand graduated licensing program found a sustained 7%-8% reduction in teen driver crash injuries attributable to the program. No other full graduated licensing system has been evaluated to date. Four studies of either a general curfew or a nighttime driving restriction for teens, a key element of graduated licensing, found substantial crash reductions during restricted hours, with 23%-25% lower crash injury and fatality rates for curfews beginning prior to midnight. One study found no change in late night crashes before and after a 1 a.m.-6 a.m. night driving restriction took effect.

Conclusions: The logic and empirical bases for graduated licensing are sound. Moreover, there is evidence that one central element, a restriction on nighttime driving by novices, reduces young driver crashes. However, a definitive conclusion about the effectiveness of GDL systems for reducing motor vehicle crashes or crash-related injuries must await examination of other GDL systems. This should be possible within the next few years, as several states and Canadian provinces have recently enacted GDL programs.