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Red-Light Camera Interventions for Reducing Traffic Violations and Traffic Crashes: A Systematic Review

NCJ Number
Date Published
2 pages

This Campbell systematic review examines the effect of red-light cameras on red light running and various types of traffic crashes; the article summarizes results from 38 studies covering 41 evaluations that were conducted in the U.S. or Australia.


Red-light cameras (RLCs) photograph violators at traffic signals; they can reduce red light running, total injury crashes, and right-angle crashes; but they may also increase the risk of rear end crashes. The impact of red-light cameras on other types of crashes, including total crashes overall, is unclear. This Campbell systematic review integrates findings from a total of 38 studies that contain 41 eligible evaluations of the effects of RLCs on red-light running, including 37 controlled before-after studies, and one controlled interrupted time series study. The authors only included before-after studies when they had a distinct control group and collected data for treatment and control conditions both before and after RLCs were put into operation; and they excluded studies involving additional interventions, such as speed cameras or enhanced police enforcement. Five of the 38 studies were assessed as having a low risk-of-bias and eight were assessed as having a moderate risk-of-bias. RLCs are effective at reducing right-angle crashes, right-angle injury crashes, and total injury crashes. However, they also appear to increase rear-end crashes. The economic implications of implementing RLC programs are unclear as few studies examined this. Studies of the effect of RLC programs on crash costs produced inconsistent results. The authors conclude that investing community and police resources in RLCs will reduce various types of traffic crashes, including total crashes involving injuries, and may reduce red light violations, but will also increase rear-end crashes. They caution that policymakers and practitioners should use evidence from better quality studies, particularly randomized controlled trials or natural experiments, and suggest that more high-quality empirical studies of RLCs are needed. Future research may be informed by the information reported in this review. Publisher Abstract Provided

Date Published: January 1, 2020