Propagation and dissipation of crash risk on saturated freeways

This paper presents a simulation-based methodology for examining the propagation and dissipation of crash risks caused by different intensities of disturbances. A modified cellular automata model is developed and validated based on survey data to simulate saturated traffic on the Pacific Motorway (Helensvale section) in Queensland. Two risk indices, individual risk and societal risk, are proposed based on the time-to-collision notion, representing the risk from distinct perspectives. The societal risk is found to be parabolically related to the intensity of the disturbance. This relationship might provide a solution for estimating crashes on saturated freeways.