What factors actually affect crash severity and how can road safety programs be better targeted?

The aim of this study was to develop a methodology that would better focus scarce road safety resources to fix those areas of the road network that have the greatest number of fatal and serious injury crashes.

Cost-benefit analysis (CBA) is used to prioritise black spot projects with the economic benefit of a remedial treatment being the difference between predicted costs of crashes with and without the proposed treatment. In NSW and AusLink CBA a crash by type methodology is used to determine the benefits of a remedial treatment. In this methodology, costs of crashes and predicted treatment effects are defined in terms of crash types. The only inclusion of a severity value is with each crash type having two cost values, one where the speed limit is less than 80 km/h, and a higher value where the speed limit is 80 km/h or more. It is felt that these current crash values have shortcomings as they place too much emphasis on projects that prevent crashes of likely low severity. Data are readily available for factors that can predict the likely severity of reported crashes and the aim of this research was to examine and use these factors to better define categories of crashes and their values. This was found to have practical implications for improving the prioritisation of road safety crash reduction programs. Categories of crashes were identified, based on differences in average severity and their relevance to possible treatments. The analysis demonstrates the higher priority of projects that address more severe crashes when crash values are determined using…