Evaluation of the Adelaide Hills speed limit change from 100 km/h to 80 km/h

Abstract

In January 2002 the speed limit was changed from 100 km/h to 80 km/h on 18 arterial roads in the Adelaide Hills area. An analysis has been conducted of the effect that these changes had on the number of casualty crashes and casualties occurring on these roads: the periods of five years before and five years after the changes have been compared. Different methods of evaluation were considered, some involving a control group and others not. Depending on which is chosen, the effect is between 3 per cent and 36 per cent reduction in casualty crashes, with 15 per cent (not statistically significant) being our preferred estimate.