The evaluation of safety efficiency of non-urban infrastructure improvements; a case-study

Abstract

This study examined the safety efficiency of infrastructure improvements applied on the non-urban roads in Israel. The improvements considered were implemented by the National Transport Infrastructure Company in the framework of a black-spots’ treatment project, over the years 2007–2009. In the study, information on about two hundred locations treated was collected, where about thirty treatment types were found suitable for evaluation. For each treatment site, accident changes were examined using after-before comparisons, accounting for changes that had occurred in the comparison-group sites and for a regression-to-the-mean. For sites with a similar treatment a weighted value of the efficiency index was produced. Both the significance of findings and their comparability with international and previous local experience were examined to assign a final list of safety effects. Finally, accident reduction factors were obtained for 19 types of road infrastructure improvements. Applying those, we estimated that the black-spots’ treatment project was associated with an average annual saving of 224 injury accidents and 531 total accidents, having a tangible economic value. Most values of safety effects observed under Israeli conditions were in line with the international knowledge, while for some and especially combined treatments, the international experience is lacking. The updated accident reduction factors are applicable for the efficiency assessment of future investments in a safer road infrastructure.