A Risk-based Methodology To Assess Run-off-road Crashes On Austrian Motorways – The Riskant Project

Run-off-road (ROR) crashes are extremely severe road accidents that often result in serious injuries or fatalities. On Austrian motorways, about 40% of all injury accidents are ROR crashes, which account for more than 60% of the fatalities on the primary road network. This is one of the reasons why the Austrian highway operator (ASFINAG) postulates in its road safety program till 2020 that new safety strategies and new road safety measures have to be developed to prevent vehicles from running off the road and (in a worst case scenario) collide with stationary obstacles on the roadside. RISKANT is a research project funded within the 2011 Call “Transportation Infrastructure Research (VIF)” of the Austrian Research Promotion Agency (FFG) in conjunction with ASFINAG. The main objective of RISKANT was to develop a risk model for crashes with stationary obstacles along the roadside. In order to achieve this goal, a so-called accident prediction model was used to estimate the probabilities of ROR crashes due to the characteristics of the road and the road environment. Furthermore, Finite element simulation studies were conducted to incorporate the severity of injuries due to collisions with different stationary obstacles. Two indices, the Acceleration Severity Index (ASI) and Theoretical Head Impact Velocity (THIV) were used to evaluate the injury risk level for vehicle occupants.