Injury Risk by Crash Severity, Belt Use and Head Restraint Type and Performance in Rear Impacts
This study assesses the exposure distribution and injury risk (MAIS 4+F) to front-outboard non-ejected occupants by crash severity, belt use and head restraint type and damage in rear impacts using 1997-2015 NASS-CDS data. Rear crashes with a delta V <24 km/h accounted for 71% of all exposed occupants. The risk of MAIS 4+F increased with delta V and was higher for unbelted than belted occupants with a risk of 11.7% ± 5.2% and 6.0% ± 1.5% respectively in 48+ km/h delta V. Approximately 12% of front-outboard occupants were in seats equipped with an integral head restraint and 86% were with an adjustable head restraint. The injury risk was 0.14% ± 0.05% and 0.22% ± 0.06%, respectively. It was higher in cases where the head restraint was listed as "damaged". Thirteen cases involving a lap-shoulder-belted occupant in a front-outboard seat in which "damage" to the adjustable head restraint were identified.