Estimates of fatal chest and abdominal injury prevention in side-impact crashes

The analysis reported in this study shows that the current NHTSA estimates of potential fatality reductions from improved side-impact protection in passenger cars are unrealistically high. This study is based on recent statistical estimates of fatality prevention by eliminating ejection and mitigating interior impact, and on an analysis of the limits of crash protection in fatal side-impact accidents. Because many fatalities involve high impact speed and significant deformation of vehicle side structures, about 70% of the near-side occupant fatalities from chest and abdominal injury are unpreventable by practical design changes. This implies that 30% of current fatalities may be prevented. Estimates of fatality prevention were then made as a fraction of the effectiveness of airbags in frontal crashes. Assuming sideinterior changes that may produce 20% of frontal airbag effectiveness, which is 6% effectiveness and is roughly the same level of safety benefit achieved with the energy-absorbing steering system, 140 fatalities per year would be prevented in all types of side-impact crashes. This estimate is a realistic but formidable goal. It is in striking contrast with NHTSA projection of 1,185 fatality reductions with relatively straightforward design changes. Their projection exaggerates potential safety improvements.