A 2007 literature review by the National Highway Traffic Safety Administration (NHTSA) documented studies of speed camera and red light camera (RLC) programs worldwide. Red light cameras are set up to photograph vehicles entering intersections after signals have turned red. Detection of an offense is made by sensors buried in the pavement and tied to a timing system integrating the traffic signal and pole-mounted camera. Photographs of a vehicle entering an intersection illegally and the license plate number are taken and then reviewed by the jurisdiction. The owner of the vehicle then may receive a citation. RLCs are used worldwide, most heavily in Australia, Canada, Europe, Singapore, and the United States.
Automated speed enforcement cameras take single spot or average vehicle speeds over several measurements. Most speed cameras use a low-powered Doppler radar speed sensor that triggers the camera to photograph vehicles traveling above a preset speed as they pass a specified point. The camera records the date, time, and vehicle speed, and usually is set to activate only when a vehicle is traveling significantly faster than the posted limit. Photo radar often is accompanied by a visible law enforcement presence to maximize the deterrence effect, but cameras can also be deployed unattended. Photographic evidence is reviewed and a citation is issued to the owner of the vehicle.
The crash reductions reported for speed cameras ranged between 9 and 51 percent. The review also discussed rigorous studies of red light camera programs in 18 U.S. cities and 6 Canadian cities. The studies typically found a decrease in right-angle crashes and an increase in rear-end crashes, with the severity of the right-angle crashes (and associated costs) outweighing that of the rear-end crashes.
(Our website has many links to other organizations. While we offer these electronic linkages for your convenience in accessing transportation-related information, please be aware that when you exit our website, the privacy and accessibility policies stated on our website may not be the same as that on other websites.)