The Impact of Radar Cameras on Traffic Speed

A Quasi-Experimental Evaluation

Abstract

This article summarizes the findings from a summative quasi-experiment that examined the impacts of radar cameras on traffic speed in Vancouver. Two arterial streets were included in the evaluation. Knight Street was subjected to a two-month intervention wherein a radar camera was set up periodically and police officers recorded both the speed and licence numbers of vehicles photographed by the camera. Traffic tickets were then mailed to the registered owners of speeding vehicles. Granville Street served as the comparison street for the quasi-experiment. Traffic speeds were measured electronically before, during, and after the intervention using an induction loop buried in the pavement on each street. ARIMA analysis of average daily speeds and percentage of vehicles exceeding the posted speed limit indicated there were significant reductions in both variables on Knight Street, whereas speeds on Granville tended to remain constant. Although these findings offer support for policies that would promote the use of radar cameras, the summative thrust of this evaluation does not allow us to clearly distinguish radar camera impacts from those attributable to the officers who actually implemented this technology.