Examination and analysis of seat belt loading marks

In moderate to severe collisions, large decelerations and hence large forces are generated. Various components of the seat belt system are loaded, and physical evidence of this loading may be observed long after the collision event. Such witness marks result from interaction between different components of the restraint system, or between the restraint and portions of the vehicle interior. Detailed examination and analysis of such marks can establish whether or not the seat belt was in use, and also the precise manner in which the seat belt was worn. Such investigative techniques are critical for evaluating the collision performance of occupant restraint systems, and for positively identifying cases of restraint system misuse. This paper reviews the types of physical evidence which may be observed to determine restraint usage.