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Effects of red light cameras on violations and crashes: a review of the international literature

Retting, Richard A.; Ferguson, Susan A.; Hakkert, A. Shalom
Traffic Injury Prevention (TIP)
March 2003

Red light running is a frequent cause of motor vehicle crashes and injuries. A primary countermeasure for red light running crashes is police traffic enforcement. In recent years, many police agencies have begun using automated red light cameras as a supplement to conventional enforcement methods. The present study reviewed and evaluated available evidence in the international literature regarding the effectiveness of cameras to reduce both red light violations and crashes. Camera enforcement generally reduces violations by an estimated 40-50%. In terms of crash effects, most studies contain methodological flaws that, to varying degrees, either overestimate (failure to adjust for regression to the mean) or underestimate (comparison with nearby signalized intersections affected by cameras) crash effects. Mindful of these limitations, the research generally indicates that camera enforcement can significantly reduce injury crashes at signalized intersections, in particular right-angle injury crashes. Most studies reported increases in rear-end crashes following camera installation. Taken together the studies indicate that, overall, injury crashes, including rear-end collisions, were reduced by 25-30% as a result of camera enforcement.