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Abstract
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PURPOSE: This is a descriptive study of the incidence and risk for severe injury in a single impact and multi-impact crashes by belt use and crash type using NASS-CDS.
METHODS: 1997-2015 NASS-CDS was used to determine the distribution of crashes by the number of impacts and severe injury (MAIS 4+F) to >15 year old non-ejected drivers by seatbelt use in 1997+ MY vehicles. It compares the risk for severe injury in a single impact and in crashes involving two, three or four+ impacts in the collision with focus on a frontal crash followed by other impacts.
RESULTS: Most vehicle crashes involve a single impact (75.4% of 44,889,518 vehicles), followed by two impact crashes (19.6%), three impact crashes (5.0%) and four+ impacts (2.6%). For lap-shoulder belted drivers, the distribution of severe injury was 42.1% in a single impact, 29.3% in two impacts, 13.4% in three impacts and 15.1% in 4+ impact crashes. The risk for a belted driver was 0.256% ± 0.031% in a single impact, 0.564% ± 0.079% in two impacts, 0.880% ± 0.125% in three impacts and 2.121% ± 0.646% in four+ impact crashes. The increase in risk from a single crash to multi-impact collisions was statistically significant (p < 0.001). In a single impact, 53.8% of belted drivers were in a frontal, 22.4% in a side, 20% in a rear crash and 1.7% in a rollover. The risk for severe injury was highest in a rollover at 0.677% ± 0.250%, then a near-side impact at 0.467% ± 0.084% and a far-side impact at 0.237% ± 0.071%. Seatbelt use was 82.4% effective in preventing severe injury (MAIS 4+F) in a rollover, 47.9% in a near-side impact and 74.8% in a far-side impact. In two impact crashes with a belted driver, the most common sequence was a rear impact followed by a frontal crash at 1,843,506 (21.5%) with a risk for severe injury of 0.100% ± 0.058%. The second most common was a frontal impact followed by another frontal crash at 1,257,264 (14.7%) with a risk of 0.401% ± 0.057%. The risk was 0.658% ± 0.271% in a frontal impact followed by a rear impact. A near-side impact followed by a rear crash had the highest risk for severe injury at 2.073% ± 1.322%.
CONCLUSIONS: Restraint systems are generally developed for a single crash or sled test. The risk for severe injury was significantly higher in two, three and four+ impact crashes than a single impact. The majority (57.9%) of severe injury occurred in multi-impact crashes with belted drivers. The evaluation of restraint performance warrants additional study in multi-impact crashes.
Language: en |