Exploring the Contribution of Interstate Two-way Two-lane Road Elements to Safety: A disaggregate Approach

In the absence of historical accident records, road authorities are faced to a problem of safety investment. Specially, this issue is arisen in case of improving the safety level of a road or a road network. Although, some studies have pointed out the hazard index of some road elements aggregately, no research is disaggregately addressed the issue. This paper addresses a disaggregate approach to identify the risk level of 47 elements of two-way two-lane roads. By introducing analytical hierarchy process (AHP), this paper explores the contribution of each road element to the road safety state. Results gained by the studied road safety experts showed that the main accident risk in the roads is due to parking and other roadside land uses, bridges, accesses and intersections, tunnels, curves and segments respectively. The study also shows that in the range of investigated factors, the top twelve factors are responsible for about 50 percent of accident probability.