Fatalities in Frontal Crashes Despite Seat Belts and Air Bags (Tech. Report)
On October 15, 2009 NHTSA issued a report on Fatalities in Frontal Crashes Despite Seat Belts and Air Bags. The principal finding is that many of the crashes involve poor structural engagement between the vehicle and its collision partner: corner impacts, oblique crashes, impacts with narrow objects, and underrides. NHTSA will issue a notice in the Federal Register inviting public comment on the report.
SUMMARY: Why are people still dying in frontal crashes despite seat belt use, air bags, and the crashworthy structures of late-model vehicles? Statistical analyses show the combination of seat belt use and air bags is highly effective, reducing fatality risk by 61 percent compared to an unbelted occupant of a vehicle not equipped with air bags – but 61 percent is not 100 percent. To address the question, an interdisciplinary NHTSA team reviewed every case of a frontal fatality to a belted driver or right-front passenger in a model year 2000 or newer vehicle in the Crashworthiness Data System (CDS) of the National Automotive Sampling System through calendar year 2007. Aside from a substantial proportion of these 122 crashes that are just exceedingly severe, the main reason people are still dying is because so many crashes involve poor structural engagement between the vehicle and its collision partner: corner impacts, oblique crashes, impacts with narrow objects, and underrides. By contrast, few if any of these 122 fatal crashes were fullfrontal or offset-frontal impacts with good structural engagement, unless the crashes were of extreme severity or the occupants exceptionally vulnerable.
FINDINGS: Summary tally of primary and secondary factors in our 122 cases: Table 3-7 (below) tallies the primary and secondary factors in the 122 fatality cases. There are a total of 186 primary factors and 265 secondary factors in these cases. The single most common primary factor was exceedingly high crash severity (37 primary occurrences). But the next three factors, underride, limited horizontal engagement, and oblique force, all sharing the characteristic of poor structural engagement, appeared a combined 60 times as primary factors. Anomalous crash circumstances, elevated occupant age, the trailer’s underride guard and tall, narrow objects are also frequent primary factors.
The single most common factor in our 122 crashes, appearing 6 times as primary and 43 times as secondary, for a total of 49, is upper-compartment intrusion. It is usually only a secondary factor because it is a consequence of “first-cause” factors, the severity or the configuration of the impact. Excessive IP intrusion, the occupant’s obesity, poor occupant-air bag interaction, and the air bag bottoming out were common secondary factors (the last, never a primary factor).
Many vehicles in the study, although model year 2000 or newer, were actually pre-2000 designs, and their relatively poor structural performance was often a severity-increasing factor, but usually a secondary factor. Front-to-front incompatibility between passenger vehicles and the occupant’s short stature were also fairly common as secondary factors. See the FULL REPORT
News related to Crash Reconstruction Topics
1 post • Page 1 of 1