DIFFICULTIES IN DETERMINING THE CAUSE OF REAL-WORLD CRASH INJURIES: A CASE STUDY OF A NASS INVESTIGATION

摘要

This paper describes a National Automotive Sampling System (NASS) case in which a parked 1958 Chevrolet Bel Air was rear-ended by a 1991 Dodge Grand Caravan whose unbelted driver sustained fatal chest injuries despite the presence of an airbag. This particular case was chosen because different reviewers of the information from the crash investigation have proposed conflicting conclusions about the role of the airbag in the fatal injuries. The NASS investigators and others concluded that the driver bottomed out the airbag resulting in fatal chest injuries. Insurance Institute for Highway Safety researchers concluded that the driver either was out of position due to late firing of the airbag or was slumped over the wheel due to a high blood alcohol concentration; in either case they attributed the fatal injuries to airbag inflation forces. Thus, in one scenario the airbag had insufficient power, and in the others it had too much power. Injury measures from a Hybrid III driver dummy seated in a Grand Caravan in a test re-creation of the real-world crash indicated low risk of serious injury to all body regions except the chest. The recorded chest compression was slightly higher than the injury reference value for a localized loading, but this measurement underestimated actual chest deflection because a postcrash inspection showed that off-axis loading had permanently deformed the ribs. During the crash test the airbag did not deploy late, but contact between the chest and steering wheel occurred because the steering column rotated upward. Separately, two static airbag deployment tests were conducted to determine the likelihood that the airbag could have caused the fatal chest injuries if the driver had been slumped over the wheel. Injury measures from these tests indicated a significant injury risk when the dummy was positioned close to the airbag module. The test results refute the hypothesis that the driver bottomed out the airbag; instead, either steering column movement or direct contact with the deploying airbag are the most likely cause of the fatal injuries.