Abstract
The City of Charlotte, North Carolina, conducted a pilot evaluation of the safety effect of speed enforcement cameras. The city selected 14 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 implementation of automated speed cameras, this study estimated long-term collision patterns from the speed enforcement program with the carryover safety effects after its termination by using an autoregressive integrated moving average (ARIMA) intervention analysis as well as a before–after analysis with comparison sites. The fitted ARIMA intervention model indicated that the treatment corridors demonstrated a significant reduction in collisions over the study periods. Furthermore, the speed camera program appeared to have significant carryover effects into the postintervention period, but collisions slowly returned to original levels. The before–after analysis with comparison sites also provided evidence that the effect of the speed camera program was to decrease collisions in the postintervention period.
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