Vehicle-driver communications to reduce rear-end collisions: What makes sense and why?

Rear-end collisions are a common type of accident that involves two or more vehicles. But, during the last thirty years only modest changes have been introduced or required in the rear lighting and signaling system on motor vehicles in the U.S., such as the high-mounted brake lamp. Others have been proposed such as coasting, deceleration and speed signals, and are discussed and evaluated. Accident data are reviewed as are models of car-following and the perceptual limitations of drivers in making judgements of closure and relative velocity. These data are used to infer the information that should be displayed to drivers to reduce rear-end collisions primarily by aiding in detection of closure and estimation of relative velocity. Preliminary tests showed that drivers can readily interpret the signals from a lighting system which codes the needed information.