The effects of mobile speed camera introduction on road traffic crashes and casualties in a rural county of England
Problem: To assess the impacts on crash and casualty numbers of the introduction of mobile speed cameras in the rural county of Norfolk, England. Method: Road traffic accident casualty and crash data were collected for two years before the introduction of cameras and two years subsequently. The casualties and crashes occurring at 29 camera sites were identified and separated from those occurring in the rest of the county. Trends in crashes and casualties, and their severity, were examined graphically and comparisons were made between before and after periods. The regression to the mean effect at individual sites was estimated. Results: After the introduction of cameras, overall crashes declined by 1% and crashes involving fatalities or serious injuries declined by 9% on the roads without cameras. At the camera sites, crashes decreased by 19% and fatal and serious crashes by 44%. The reduction in total crashes was significantly greater than that expected from the effect of regression to the mean in twelve out of 20 sites tested. Summary: The introduction of cameras appears to have resulted in real and measurable reductions in crash risk in this rural country.
Journal of Safety Research, 39, 101-110