| Objective
To assess the degree to which speed limits are being set in accordance with the Safe System, with fatal crash rates remaining negligible regardless of speed limit. A further objective was to examine the reduction in fatal crashes that could be achieved if the fatal crash rate were equal to the lowest fatality rate in a common speed zone.
Method
Police reported crashes from 2016 to 2023 in two Australian states were used to calculate the fatal crash rate by speed limit. The analysis was conducted at three levels; combined data, by state, and by state and area. Fatal crash reductions were projected based on all speed zones having a fatal crash rate equal to that for roads with a speed limit of 50 km/h.
Results
The fatal crash rates were found to be non-negligible at all speed limits. Furthermore, the fatal crash rates generally increased as speed limits increased. This suggests that the speed limits in Australia do not sufficiently account for the different levels of risk found on the road network. In an 80 km/h zone, the risk of a crash being fatal is three times higher than in a 50 km/h zone and, in a 100 km/h zone, it is more than six times that of a 50 km/h zone. Of particular concern is the 110 km/h zones in South Australia, where the risk of a crash being fatal is more than 12 times higher than in a 50 km/h zone. It was found that, if the fatal crash rate for all speed zones was equal to the rate in 50 km/h zones, the number of fatal crashes would be reduced by between 46.2% and 55.5%.
Conclusions
Speed limits in Australia are not sufficiently matched to the risk to road users should a crash occur, with substantial increases in the fatal crash rate at speeds limits of 80 km/h and above. A uniform fatal crash rate equal to the fatal crash rate found in 50 km/h zones would halve the number of fatal crashes. Lowering the fatal crash rate in Australia could be achieved through improvements to the roads, improvements in the passive safety of vehicles, and the lowering of speed limits, or a combination of these approaches. | 