Vehicle travelling speeds and fatal pedestrian crashes in Adelaide

Abstract

The aim of this study was to examine the relationship between travelling speeds of vehicles and the incidence of pedestrian fatalities in Adelaide, Australia. The study was based on the results of detailed investigations of 176 fatal pedestrian crashes in the Adelaide area between 1983 and 1991. The impact speed of a striking vehicle is a function of its travelling speed and factors relating to any braking manoeuvre attempted before the collision. It is therefore possible to express the impact speed of the striking vehicle as a function of its travelling speed. In turn a relationship between the striking speed of vehicles and the fatality risk can be used to estimate the effect that altered travelling speeds would have had on the numbers of fatalities in the sample, as well as the number of collisions that would have been avoided all together. A reduction in the speed limit from 60 to 50 km/h was one of 4 speed reduction scenarios that are considered. The smallest estimated reduction in fatal pedestrian collisions in the selection presented was 13 percent, for a scenario in which all drivers obeyed the existing speed limit. The largest estimated reduction was 48 percent for a scenario in which all drivers were travelling 10 km/h slower. The estimated reductions in fatalities obtained in this study are compared with those observed in places where the urban area speed limit has been lowered. The results of this study were previously reported in the journal Accident Analysis and Prevention (vol 29, no 5, pp. 667 - 674).