The effect of combined speed and red light cameras on safety

Abstract

Combined speed and red light cameras are a widely implemented enforcement measure. Previous research already examined the effect of red-light cameras, however the effect of combined speed and red light cameras on severe crashes has not been examined thoroughly. This study evaluates the traffic safety effect of combined speed and red light cameras at 253 intersections in Flanders-Belgium that were installed between 2002 and 2007. The adopted approach was an empirical Bayes method. The evolution in the number of crashes at the investigated locations was compared with the evolution in a comparison group of locations. These analyses show a non-significant increase of 5-9% in the number of injury crashes. For the severe crashes, with serious and fatal injuries, a decrease of 14-18% was found. A distinction between side and rear-end crashes showed a significant increase of 44% in the number of rear-end crashes, but a non-significant decrease of 6% in the number of side collisions. The decrease for the severe crashes was mainly attributable to the effect on side-collisions, for which a significant decrease of 24% was found. Furthermore ANOVA-analyses showed combined speed and red light camera equipped intersections outside the urban area yield more favorable results, compared to intersections inside the urban area. From this study can be concluded combined speed and red light cameras have a favorable effect on traffic safety, especially on severe crashes. Future research should however examine the circumstances of rear-end crashes and how these can be handled.