The relationship between free travelling speed and the risk of involvement in a casualty crash in 60 km/h speed limit zones was investigated by the Road Accident Research Unit in Adelaide using a case control study design. The 151 case vehicles were passenger cars involved in crashes which were investigated at the scene by the Unit and reconstructed using the latest computer aided crash reconstruction techniques. The 604 control vehicles were passenger cars matched to the cases by location, direction of travel, time of day, and day of week and their free travelling speeds were measured with a laser speed meter. It was found that the risk of involvement in a casualty crash doubled with each 5 km/h increase in speed above 60 km/h. By comparing these risks with those associated with alcohol in a study also conducted by the Road Accident Research Unit in Adelaide it was found that each 5 km/h increase in travelling speed above 60 km/h increases the risk of a casualty crash by roughly the same amount as each increase of 0.05 above a zero blood alcohol concentration. Comments are made on the implications of these findings for the setting and enforcement of speed limits. (Author/publisher) For the covering entry of this conference, please see ITRD abstract no. E205827.
Abstract