Abstract
Forward collision warning systems (FCWS) are expected to reduce road accident and casualties but this will require optimised design. The results ofa series of experimental investigations of driver response to a FCWS suggest that with an early alarm drivers respond with a faster accelerator release although the accelerator release to brake onset is largely unchanged.Early alarms provide more 'thinking time' which may result in faster braking. The perceived benefit results in higher trust ratings and greater toleration of false alarms. Driver response to system failure (unreliability)was found to be influenced by trust and alarm timing