In most road traffic accidents the vehicles involved will be damaged or marked. An analysis of the profile or pattern of the damage can lead to a determination of vehicle speed and relative vehicle orientation at impact.
Special computer programmes are available which allow reasonably accurate determinations of speed and orientation to be carried out. The calculations are based on measurements of the damage profile and the results of official crash tests.
In pedestrian accidents, the vehicle damage and marks on the vehicle will be related to the actions of the pedestrian and will correlate with the injuries sustained by the pedestrian.
In rare cases, a driver will claim some fault with the vehicle. An examination of the vehicle may reveal whether such a claim is justified.