Behavioural adaptation in drivers is discussed with particular reference to speed, sight distance, lane keeping and car following. The importance of reaction time to road safety is outlined. It is difficult to research drivers' reactions to emergencies because of the risks involved, but the responses of drivers requested to stop by a police officer positioned at the side of the road was studied. Faster drivers reacted faster as they had less time in which to stop. Reaction times were more variable in drivers travelling at lower speeds. In another study older drivers had a longer perception time but moved their foot to the brake pedal more swiftly than younger drivers. The influence of speed on visual search patterns is described in relation to an experiment at a mini roundabout with a priority cycle crossing. Drivers looked left for oncoming traffic but failed to check to the right for the cyclists. The use of speed humps at roundabouts to give the driver more time to observe is suggested.
Abstract