Safety restraint usage in fatal motor vehicle crashes.

In 1987, following implementation of the Washington safety restraint mandatory usage law, collision statistics indicated an increase in motor vehicle crashes in which occupants had died while utilizing safety restraints. Because of concerns expressed by restraint use law advocates, a "Fatal Collision Research Team" was established to evaluate and reconstruct collisions in which restrained occupants had died. Collisions were analyzed over a three-year period and included 337 crashes involving 1,058 occupants, of whom 446 died. The team analyzed fatal collisions involving restrained occupants and documented restraint usage as well as severity of the crash. Crash severity was measured using either the Collision Deformation Classification (CDC) system, which defines the extent of crush to the vehicle, and/or intrusion into the passenger occupant area, or by measuring deceleration forces (delta v) acting on the vehicle, where sufficient data existed to do so. The survivability of the crash was determined individually for each occupant and independently of whether the occupant lived or died, as well as whether the occupant was restrained or not. The major findings were: (i) that in the majority of cases where a restrained occupant died, the fatality can be attributed to the extent of vehicle crush and deceleration forces, i.e. the crash forces and dynamics made the crash nonsurvivable, and (ii) restraint misuse seemed not to be a major contributory factor in fatal crash injuries.