Factors contributing to serious and fatal injuries in belted rear seat occupants in frontal crashes

Rear-seat occupant demographics in rear impacts: Analysis of NASS-CDS

PURPOSE

This study analyzes field accidents to identify rear-occupant exposure and injury by crash types. Occupant demographics and injury were assessed by body region and crash severity to understand rear-occupant injury mechanisms in rear crashes.

METHODS

The exposure and serious-to-fatal injury was determined by crash type for non-ejected second- and third- row occupants in 1994+ MY vehicles using 1994-2015 NASS-CDS. Selected occupant demographics and serious injury distributions were assessed over a range of delta V for rear crashes.

RESULTS

Rear crashes accounted for 8.7% of exposed and 5.4% of serious-to-fatally injured rear-seat occupants. On average, rear-seat occupants were 14.3 ± 1.5 years old (median 10.3, 90^th CI 0.08-29.6), weighed 44.7 ± 2.6 kg (median 44.4, 90^th CI 7.9-81.7) and were 130.3 ± 4.1 cm tall (median 141.4, 90^th CI 67.3-178.4). With serious injury, the average rear occupant was 18.1 ± 5.8 years old (median 13.1, 90^th CI 0.0-47.2), weighed 42.6 ± 10.7 kg (median 31.4, 90^th CI 7.0-82.4) and was 120.6 ± 15.4 cm tall (median 145.4, 90^th CI 48.8-174.1). More than 72% of rear-seat occupants were in delta V less than 24 km/h. Less than 2% were in delta V 48 km/h or greater. The overall rate of serious-to-fatally injured (MAIS 3 + F) was 0.73% ± 0.37%. For serious-to-fatally injured rear-seat occupants, the average delta V was 37.4 ± 3.1 km/h (median 29.8, 90th CI 28.6-62.1). None were involved in delta Vs less than 24 km/h, about 78% were in a delta V between 24-48 km/h and 22% were in a delta V of 48 km/h or greater. Head and chest were most commonly injured, irrespective of crash severity.

CONCLUSIONS

The height and weight of a 10-year old and 5^th Hybrid III ATD are representative of the average rear-seat occupant involved in rear crashes based on NASS-CDS. Crash tests with a delta V of between 30 and 37 km/h represent the typical collision causing serious-to-fatal injury.

Autopsy findings in drivers and passengers from fatal motor vehicle collisions: limited differences in injury patterns and toxicological test results

We performed a retrospective study of the injuries and characteristics of occupant fatalities in motor vehicle collisions in southeast Norway. The goal was to provide updated knowledge of injuries sustained in modern vehicles and detect possible differences in injury pattern between drivers and passengers. Forensic autopsy reports, police, and collision investigation reports from 2000 to 2014 were studied, data extracted and analyzed.

A total of 284 drivers, 80 front-seat passengers, and 37 rear-seat passengers were included, of which 67.3% died in front collisions, 13.7% in near-side impacts, 13.5% in rollovers and 5.5% in other/combined collisions. Overall, 80.5% died within one hour after the crash. The presence of fatal injuries to the head, neck, thorax and abdomen were observed in 63.6%, 10.7%, 61.6% and 27.4% respectively. All occupants with severe injuries to the head or neck had signs of direct impact with contact point injuries to the skin or skull. Injuries to the heart and spleen were less common in front-seat passengers compared to drivers. Seat belt abrasions were more common and lower extremity fractures less common in both front-seat and rear-seat passengers compared to drivers. Blood alcohol and/or drug concentrations suggestive of impairment were present in 30% of all occupants, with alcohol more often detected among front-seat passengers compared to drivers.

Few driver-specific and passenger-specific patterns of injury could be identified. When attempting to assess an occupant’s seating position within a vehicle, autopsy findings should be interpreted with caution and only in conjunction with documentation from the crash scene.