Safety Impact of Speed and Red Light Cameras

In-person enforcement is the most common form of speed enforcement in the United States. It has several limitations; law enforcement officers are able to stop only a small proportion of speeders. Road design and traffic conditions can make roadside stops difficult, and stops can be dangerous for both the driver and the law enforcement officer, who are at risk from being struck by passing vehicles as well as from each other. Similarly, officers are rarely on the scene when a motorist runs a red light. Automated traffic enforcement (ATE), such as cameras that capture images of vehicles that are traveling above the speed limit or running stop lights, addresses several of the limitations of in-person speed and red light enforcement: such systems can monitor thousands of cars an hour, are consistent and tireless, and do not put drivers or law enforcement officers at risk during the ticketing process. They raise other issues: their use has been challenged on legal grounds; some studies have found that while red light cameras reduce the number of right-angle crashes, they may increase the number of rear-end collisions; and ATE systems often incite complaints that they are being used to raise revenue rather than to promote safety. The National Highway Traffic Safety Administration (NHTSA) has recommended that ATE systems be used to supplement, not replace, in-person speed enforcement. This document is available from the US Confressional Research Service at https://crsreports.congress.gov/product/pdf/R/R46552