Driver reaction times to familiar but unexpected events

In collision investigation, 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) is of considerable importance when reconstructing an incident.

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.