The city of Charlotte, North Carolina conducted a pilot evaluation of thesafety effect of speed enforcement cameras. The city selected fourteen key corridors with high collisions, and an automated speed enforcement camera program was implemented in the corridors scattered throughout Charlotte from September 2004 through July 2006. In addition to comparing the net safety effectiveness before and after implementing automated speed cameras, this study estimated long-term collision patterns from the speed enforcement program with the carry-over safety effects after its termination by using an autoregressive integrated moving average (ARIMA) intervention analysis as well as using a before-after analysis with comparison sites. Thefitted ARIMA intervention model indicates that the treatment corridors demonstrated a significant reduction in collisions over the study periods. Furthermore, the speed camera program appeared to have significant carry-over effects into the ¡°post-intervention¡± period, but collisions were slowly returning to the original levels. The before-after analysis with comparison sites also provided evidence that the effect of the speed camera program was a decrease in collisions into the post-intervention period.
Abstract