A primary cause of rear-end collisions seems to be misperception of relative speed between vehicles. This has led to the suggestion that such collisions may be reduced by a form of display incorporating an indication of the relative velocity or rate of deceleration of the lead car. This paper presents a study of the Collision Avoidance Brake Light System (CABLS), which has been proposed to improve display conspicuity and convey information about the extent of dynamic change in velocity (severity of braking). This system uses an oversized array of light emitting diode (LED) indicators, fitted to either side of the standard central high-mounted stop lamp (CHMSL). The study aimed at an early evaluation of the CABLS concept, and was designed to focus on the initial reaction of drivers to such a new brake light display. The sample contained 55 drivers, with matched demographic characteristics, who were assigned to three types of brake system conditions: (1) a standard CHMSL; (2) a CABLS integrated with the CHMSL; and (3) a random version of CABLS. Traffic scenarios were created in a simulator environment, and the subjects were questioned about brake light systems, and their perceptions of and attitudes to the CABLS were reported. Further research is needed to find out which version of CABLS is better.
Abstract