Drivers' Judgments of Safe Distances in Vehicle Following

Driver behavior in the vehicle-following situation, a major source of road accidents, was investigated using a controlled-track experiment. Drivers were found to adopt headways of approximately 2 s irrespective of speed of travel, driving experience, or instructed probability of the leading vehicle's stopping. Under the optimal conditions used, drivers demonstrated that such headways were more than adequate to avoid tail-end collisions in an emergency situation. The implications of these results for the development of perceptual-motor support devices and the attribution of causes in road accidents are discussed.