Reducing accidents on highways has always been one of the most important tasks for highway engineers. Estimating the number of accidents that may result from a given highway design is important in evaluating different alternatives. For this purpose the FHWA developed the Interactive Highway Safety Designs Model (IHSDM), a suite of software for analyzing two-lane rural highways in the United States. A key component of IHSDM is the Crash Prediction Module (CPM), which estimates the number of accidents on road segments. CPM was applied to two actual Italian two-lane rural roads to evaluate its capability to produce reasonably reliable crash predictions in the Italian context. The results of the case study showed considerable differences between the crash predicted and the crash data, underlining the difficulty of transferring this tool to the Italian context.
