Evaluating the safety effects of infrastructure measures on non-urban roads, in Israel

In Israel, the Netivey Israel Company carries out infrastructure improvements on non-urban roads, focusing on hazardous locations - road sections and junctions with high accident rates. To examine the impacts attained and provide a better basis for future treatments, safety effects of the applied measures should be assessed. A safety effect reflects the percentage of accident reduction associated with the treatment, which is also known as an accident modification factor. Internationally, many safety effects were reported. However, as road and traffic conditions are not identical among countries, more evaluation studies may enrich the current knowledge. In this study, we examined the safety effects of seven infrastructure measures, which were applied at 37 sites, including: median barrier installation, flattening horizontal curves and upgrading to a dual-carriageway, on two-lane road sections; traffic lights’ installation and converting to a roundabout, at un-signalized junctions; geometric realignments and traffic-signal program improvements, at signalized junctions. For each treatment site, accident changes were analyzed using after-before comparisons with comparison-groups, accounting for accident trends and a regression-to-the-mean. For each treatment type, a weighted safety effect was produced. The analysis referred to total injury accidents, severe accidents and vehicle collisions, while considering two comparison-groups. To assign a final list of safety effects, the findings’ significance and their comparability with international experience were examined. The results showed significant accident reductions, of 30%-60%, for all treatments of two-lane road sections and roundabouts, and decreasing trends for other measures. In the sites treated, the annual savings were estimated at 29 injury accidents, with total costs of about 6 million US$. The study demonstrated positive safety impacts of road infrastructure measures and provided new values of safety effects for international knowledge.