The Relationship Between Vertical Velocity and Roof Crush in Rollover Crashes

Rollover accidents account for a large number of serious to fatal injuries annually. In the past, these injuries were often the result of unrestrained occupant ejection. Subsequent to mandatory belt use laws, a larger percentage of these injuries occur inside the vehicle, and the head and neck areas sustain a substantial number of these injuries. Rollovers have been characterized as violent events, roof crush as the natural consequence of such violence. Further, head and neck injury have been thus considered unavoidable, even with occupant use of the production restraints.

This paper will describe the relationship between the three dimensional extent (severity) of roof crush and the equivalent drop test contact velocity as derived from physical experiments and tests. The drop test contact velocity is directly related to the cumulative change of velocity experienced by a vehicle as a result of roof contact deformation during a rollover accident by validated computer simulations. The conclusion is that a summary range of impact velocities to produce more than 15 cm of roof crush for most on-the-road cars and light trucks from 1988 to 1992, is approximately 1 to 2 m/s.