A detailed investigation of crash risk reduction resulting from red light cameras in small urban areas

This is an update to the October, 2003 version of this report. Using the latest available data, we include an additional 12 months of accident data. Additionally, several data coding errors were discovered in the original data set, and corrected for this report. Therefore, results from the October, 2003 report should be disregarded. This paper analyzes the impact of red-light cameras (RLCs) on crashes at signalized intersections. It examines total crashes and also breaks crashes into categories based on both severity (e.g. causing severe injuries or only property damage) and by type (e.g. angle, rear end). Prompted by criticism of the simplistic methods and small data sets used in many studies of red light cameras, we relate the occurrence of these crashes to the characteristics of signalized intersections, presence or absence of RLC, traffic, weather and other variables. Using a large data set including 26 months before the introduction of RLCs, we analyze reported accidents occurring near 303 intersections over a 57 month period, for a total of 17,271 observations.