Rollover Crash Sensing and Safety Overview 2004-01-0342

This paper provides an overview of rollover crash safety, including field crash statistics, pre- and rollover dynamics, test procedures and dummy responses as well as a bibliography of pertinent literature. Based on the 2001 Traffic Safety Facts published by NHTSA, rollovers account for 10.5% of the first harmful events in fatal crashes; but, 19.5% of vehicles in fatal crashes had a rollover in the impact sequence. Based on an analysis of the 1993-2001 NASS for non-ejected occupants, 10.5% of occupants are exposed to rollovers, but these occupants experience a high proportion of AIS 3-6 injury (16.1% for belted and 23.9% for unbelted occupants). The head and thorax are the most seriously injured body regions in rollovers.

This paper also describes a research program aimed at defining rollover sensing requirements to activate belt pretensioners, roof-rail airbags and convertible pop-up rollbars. The work required an understanding of the most relevant conditions for field rollovers, vehicle responses and occupant kinematics in the vehicle. The most common rollovers involve a soil trip, fall-over and curb trip. These conditions were simulated in laboratory tests where measurements were made with rate gyros, accelerometers and instrumented dummies. Cross-plots of vehicle roll rate and angle were used to consider triggering requirements for safety systems and to determine the timing of occupant motion in the vehicle. Some rollovers require triggering of safety systems when the vehicle has only a 10°-20° roll angle because roll angular velocities exceed 100°/s.