Introducing Alignment Based Risk Indices into the Highway Traffic Accident Analysis

A traffic accident analysis method based on the accident risk index according to the combination of alignment elements is developed and tested applying geographic information systems (GIS). This study is based on crash experience on curves of 4-lane expressways in Korea from 1996 – 2000, and that finding relates only to curves. Impacts of alignment elements on traffic accidents have been identified by examining accidents that occurred under different alignment conditions and by investigating traffic accident risk indices (TARI). Traffic accident rates are estimated more reasonably by considering the interaction between alignment factors and the design consistency. Traffic accident risk indices and risk grades are suggested in the traffic accident data-based approach. Finally, estimating traffic accident rates, evaluating the level of risk and then visualizing information graphically by means of GIS are combined into one system called the risk rating system. This risk rating system is expected to play a major role in designing expressways and developing countermeasures for expressway sections susceptible to traffic accidents.