An evaluation of the effectiveness of red-light cameras at signalized intersections.

In most developed countries, a relatively large proportion of motor vehicle crashes and injuries occur at signalized intersections. For example, in the United States approximately 21% of all crashes and 23% of injury crashes occur at signalized intersections. Red light running is a significant cause of such crashes. It is estimated that some 260,000 red light running crashes occur in the U.S. annually, of which 750 are fatal. A primary countermeasure for red light running crashes is police traffic enforcement, and in recent years, many police agencies have begun using automated red light cameras as a supplement to conventional police enforcement methods. This study reviewed and evaluated much of the available evidence on the effectiveness of red light cameras to reduce the numbers of drivers running red lights and to reduce the number and severity of crashes after red-light camera programs were introduced. Nine studies, from the United States, Australia, Singapore, Great Britain and the Netherlands provided information on the number of red-light violations at signalized intersections, of which 4 studies reported on violation rates before and after the introduction of camera enforcement programs. Although the studies used different definitions of violation rates, a 40-50% reduction in violation rates was generally noted. In terms of crash reductions, 13 studies were found with information on crashes at signalized intersections with particular reference to red-light running (RLR). Of these, six studies provided detailed information on the reductions in the number of crashes that occurred after the introduction of a RLR camera enforcement program. After performing a meta-analysis it was concluded that overall reductions of 20% in all crashes (based on five studies) and of 27% in crashes with injuries (based on six studies) are the best estimates on the basis of those studies that provided detailed information on the number of crashes. Other studies that provided information on changes in crash rates associated with red light camera enforcement indicate a wider range of crash reductions, but none indicate any increase in crash risk. A number of other aspects, associated with the issue of red-light camera programs, such as the driver, traffic and geometric characteristics that influence the frequency of red light violations are also briefly touched upon. For the covering abstract see ITRD E124693.