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This study, which is an extension of an earlier study, examined an additional 64 frontal crashes of airbag-equipped vehicles in the 1997-98 National Automotive Sampling System Crashworthiness Data System (NASS/CDS) in which the driver died. The principal cause of death in each case was determined based on an examination of the publicly available case materials, which primarily consisted of the crash narrative, the injury/source summary, and photographs of the crashed vehicle. Results were consistent with the earlier analyses of the 1990-96 NASS/CDS files. In the combined data set (1990-98), gross deformation of the occupant compartment was the leading cause (42 percent) of driver deaths in these 116 frontal crashes. The force of the deploying airbag (16 percent) and ejection from the vehicle (13 percent) also accounted for significant portions of the driver deaths in these frontal crashes. There continues to be little or no evidence that airbags deploy with too little energy.

Excessive movement of steering columns in crashes can significantly degrade the performance of restraints, especially airbags. Although steering column movement does not appear to be a major problem in full-width rigid barrier crashes, it can be an issue in other frontal crash types. Results from 106 frontal offset crash tests at 64 km/h (40 mi/h) were used to characterize different patterns of steering column intrusion for different vehicle types. Large movements of the steering column often were associated with the dummy’s head striking the steering wheel through the airbag. Some of the tested models were redesigned over the course of this testing, and comparisons with older designs showed that improving the structural integrity of the occupant compartment could lead to less longitudinal movement of the steering column, but this was not necessarily the case for vertical column movements for some models in the data set.

Since 1978, the National Highway Traffic Safety Administration (NHTSA) has been testing the frontal crash protection provided by new cars in the United States. In the New Car Assessment Program (NCAP), vehicles are crashed into a stationary, full width, rigid barrier at 35 mi/h (56 km/h). Occupant protection is measured by comparing accelerations, forces, and deflections experienced by the head, chest, and upper legs of 50th percentile male Hybrid II or III anthropometric dummies restrained in the driver and right front seat passenger positions. The procedures are similar to those specified in Federal Motor Vehicle Safety Standard 208, except that the speed is 5 mi/h faster resulting in a test that requires the car to manage 36 percent more energy.

In 2012, the Insurance Institute for Highway Safety (IIHS) began a 64 km/h small overlap frontal crash test consumer information test program. Thirteen automakers already have redesigned models to improve test performance. One or more distinct strategies are evident in these redesigns: reinforcement of the occupant compartment, use of energy-absorbing fender structures, and the addition of engagement structures to induce vehicle lateral translation. Each strategy influences vehicle kinematics, posing additional challenges for the restraint systems. The objective of this two-part study was to examine how vehicles were modified to improve small overlap test performance and then to examine how these modifications affect dummy response and restraint system performance. Among eight models tested before and after design changes, occupant compartment intrusion reductions ranged from 6 cm to 45 cm, with the highest reductions observed in models with the largest number of modifications.

The Insurance Institute for Highway Safety (IIHS) is investigating small overlap crash test procedures for a possible consumer information program. Analysis of real-world small overlap crashes found a strong relationship between serious head and chest injuries and occupant compartment intrusion. The main sources of serious head injuries were from the A-pillar, dash panel, or door structure, suggesting head trajectories forward and outboard possibly bypassing the airbag. Chest injuries mainly were from steering wheel intrusion and seat belt loading. In developing this program, two test dummies were evaluated for predicting occupant injury risk: midsize male Hybrid III and THOR. In the collinear small overlap crash tests conducted here, results from the two dummies were similar. Both predicted a low risk of injury to the head and chest and sometimes a high risk of injury to the lower extremities. Head and torso kinematics also were similar between dummies.