Implementation of automated enforcement programs for traffic signals is increasing in the United States. Fines assessed by the programs, which are based on photographs or videos captured automatically when a vehicle enters the intersection after the signal has changed to red, range from $50 to $271 dollars. The cameras used in the systems cost about $50,000 to $60,000, with installation, including detectors, equipment cabinet, and mounting pole, adding approximately an additional $25,000. Monthly operating costs are approximately $5,000. In the U.S., a private sector contractor that receives a portion of the fine revenue collected from the systems typically undertakes installation and operation. Public opinion surveys reported in the literature indicate significant public support for the programs. The percentage of survey respondents approving of the systems ranges from approximately 60% to 80%. Impacts of the systems on the safety of the transportation system are difficult to assess. There is substantial literature documenting a significant decline in the number of vehicles committing traffic signal violations at enforcement sites, ranging from 20% to 87%. However, the few independent analyses of the occurrence of crashes at these sites offer no definitive indication of whether the camera systems impact this important measure of transportation safety. An early Australian study indicated significant reductions in crashes due to implementation of camera enforcement, while a later study found that over time there were no significant changes in crash behaviour due to the systems (though the small number of crashes experienced at the studied sites clouded the results). Studies of the systems in use in Scotland found both a significant crash reduction and that the most significant impact on violation behaviour was a decrease in vehicles entering the intersection between 0.5 and 5 seconds into the red phase. A study of city-wide crashes over the same time period found that red light cameras were likely one of several factors contributing to the overall decline in accidents. A graduate student study of two intersections with automated enforcement in Howard County, Maryland indicated a positive impact of the systems on right-angle crashes. A Mitretek analysis of data provided by Howard County on crash experience at each of the 25 enforced intersections in that county indicated that the reported reduction in both right-angle and rear-end collisions were statistically significant. Several factors were identified that cloud the interpretation of reported safety impacts, including study design issues and the influence of other traffic safety improvements concurrent with the implementation of red light cameras. This report makes several recommendations for further research into the impacts of red light camera systems. Despite the inherent difficulties of long term transportation safety impact studies, one or more such studies performed by an independent agency on a U.S. red light camera system would provide a better understanding of the impact that red light cameras have on U.S. driver populations. A second effort that may help document any safety impact of these systems would be a detailed review of automatic camera recorded violation data from several jurisdictions to determine if red light violations at particular times during the red phase are more likely to result in crashes, and whether or not red light camera systems in the U.S. are significantly reducing these types of violations. The final recommended area of further research in this area is benefit/cost analysis of the systems. The ability of the systems to reduce crashes should be compared to the costs of operating the systems as well as the total value of fines assessed to signal violators. (Author/publisher)
Samenvatting