Speed camera programs can reduce crashes by 9 to 51 percent.
Results from a Worldwide evaluation of automated speed enforcement.
Made Public Date


United States



Automated Enforcement: A Compendium of Worldwide Evaluations of Results

Summary Information

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 relationship between speed and traffic safety is generally well accepted by researchers and public safety officials. That higher speeds are associated with increasing crash severity is particularly difficult to deny, both from highway safety research and physical laws. Correlational studies also suggest that the probability of a crash is related to speed, both on an individual level and on an average traffic speed level, although the evidence is not as conclusive. The incidence of single vehicle (run-off-road) crashes increases sharply with higher speeds, providing additional suggestive evidence of a relationship between crash frequency and speed.


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.

Automated Enforcement: A Compendium of Worldwide Evaluations of Results

Automated Enforcement: A Compendium of Worldwide Evaluations of Results
Publication Sort Date
Decina, Lawrence E. et al.
U.S. DOT National Highway Traffic Safety Administration

(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.)

Application Taxonomy

Goal Areas