Safety priorities for occupant protection in rear impacts

Rear-impact electronic cases were reviewed for serious injury to rear-seated children and adults to identify mechanisms of injury and consider priorities, countermeasures and safety concepts.

1997-2015 NASS-CDS and 2017-2020 CISS electronic cases were analyzed for serious injury (MAIS 3+F) to rear-seated children 0-14 yo (years old) and adults 15+ yo in rear impacts.

31 children and 43 adults were identified with serious injury. 86.0% of child injury was related to intrusion of rear structures with injury by direct force (55.3%), compression into front interior (27.5%) or acceleration into impact (3.2%). 14.0% of injury was not related to intrusion with front-seatback rotation (12.3%) or direct force (1.7%). Only 45.1 ± 17.6% of injured children were properly restrained. 68.0% of adult injury was related to intrusion of rear structures with injury by direct force (46.2%), compression into front interior (15.3%) and acceleration into impact (6.4%). 21.6% of injury was not related to intrusion with front seatback rotation (2.5%) or direct force (19.1%). 10.4% was from ejection and ground impact without seatbelt use. Only 17.8 ± 7.5% of injured adults were restrained. Priorities, countermeasure and concepts were considered to improve occupant protection in rear impacts: 1) new rear impact test with the IIHS high-hood barrier offset to the rear at 55 mph to reduce rear-seat intrusion, 2) stepped-up campaigns for proper child seat selection and use, particularly for infants and toddlers <2 yo and adult use of seatbelts in rear seats, 3) adoption of FMVSS 201L to reduce head injury risks of children impacting the rear interior below the beltline, 4) improved front seats by shifting restraining forces from the seatback to the cushion frame with an anti-ramping guide that retains the pelvis on the seat and reduces seatback rotation, 5) changes in front seatbelts to provide early restraint of occupant movement by a rear-impact pretensioner that moves the lap-belt anchors and gives a favorable angle for early lap-belt restraint or a rear wrap-around lap belt so the occupant moves into the belt in a rear impact, 6) implementation of kinematic controls on front-occupant movement that reduces ramping in severe rear impacts, 7) guarding the area around rear-seated child with an after-market ring structure that maintains space around the child and blocks rearward rotation of the front seatback and 8)-25) recommendations.

The primary mechanism for injury to rear-seated children and adults is intrusion, often without appropriate occupant restraint. There are priorities to improve protection by reducing intrusion, guarding the area around children, shifting front-occupant loads to the cushion frame and improving occupant restraints.