Driver reaction times to familiar but unexpected events

The 'Driver Reaction Times to Familiar but Unexpected Events' study was undertaken as part of the TRL re-investment program to promote internal research. The study was designed to take advantage of existing data collected during previous trials in the CARSIM, together with bespoke studies designed to be integrated into new trials. In collision investigation, it is the perception and response of a driver to a familiar, but unexpected event (such as the sudden movement of a pedestrian crossing from behind a parked vehicle) that is of considerable importance when reconstructing an incident for criminal or civil proceedings. The reaction times measured in the trials in this TRL study, appear to be consistent with the work of Olson, partially because of the nature of the definition of Olson's reaction time range. Instead of taking the range as fixed, the collision investigator needs to understand how the range was calculated and whether a particular event needs the range to be modified, such as when the detection and identification phases may have been undertaken before a particular hazard enters the road.