Incidence and Mechanism of Head, Cervical Spine, and Lumbar Spine Injuries for Occupants in Low- to Moderate-Speed Rear-End Collisions

Automotive accidents and subsequent personal injury claims incur significant costs annually. While seat and head restraint design continue to evolve and improve, occupant safety and injury risk assessment in rear-end collisions remain at the forefront of automotive innovation. In this study, we combined statistical analyses of nine years (2007-2015) of data from the National Automotive Sampling System Crashworthiness Data System (NASS-CDS) database and one year (2017) of data from the Crash Investigation Sampling System (CISS) database with data acquired from vehicle-to-vehicle crash tests conducted with instrumented anthropomorphic test device (ATD) occupants in order to compare and relate field injury rates with potential mechanisms underlying head, cervical spine, and lumbar spine injuries in low-to moderate-speed rear-end collisions. In the first portion of the study, we performed statistical analyses of the NASS-CDS and CISS databases to estimate the incidence rate of AIS 2+ and AIS 3+ head, cervical spine, and lumbar spine injuries, as well as a subset of AIS 1 head injuries, including recorded headaches, unconsciousness, and concussion. The results of these analyses were compared to measured occupant loading data from rear-end crash tests performed at various delta-Vs ranging from 5.6 to 19.5 km/h, using restrained, nominally positioned, and instrumented Hybrid III 50th percentile male ATDs. Kinematic and kinetic data for the head, cervical spine, and lumbar spine collected in the low- to moderate-speed rear-end crash tests were found to be well below injury thresholds. Analysis of the NASS-CDS and CISS databases demonstrated low rates of injury to the head, cervical spine, and lumbar spine in low- to moderate-speed rear-end collisions. A review of these rear-end crashes revealed that, outside of collision speed and crash severity, muscle activation, occupant age, and occupant gender may play a role in increasing the likelihood of injury.