ARCCA was called to determine how and why a seatbelt caused a paralyzing neck injury to the front seat passenger.
ARCCA’s engineering experts analyzed the accident and the seat design:
The vehicle’s restraint system involved an “automatic” seat belt system where the shoulder belt put itself in position automatically. The lap belt had to be fastened manually.
The seat bottom and a knee bolster were supposed to protect the occupant’s lower body and help keep the occupant in the seat in the event of a collision.
In the actual accident, the seat bottom structure collapsed, which allowed the passenger to sink to a lower position.
As the passenger moved to a lower position during the collision, the seat belt remained fixed. This led to the belt transferring force to the passenger’s neck, rather than to their chest and shoulder as intended.
The ARCCA Experts concluded that by allowing the passenger to sink to a lower position, the seat bottom failure caused the shoulder belt to exert stress on the passenger’s neck, which fractured their C3-C4 vertebrae and resulted in quadriplegia.
The automatic seat belt design in the subject vehicle was an attempt to meet a federal requirement that all vehicles manufactured after September 1, 1983 have a “passive” restraint system that require no action by the occupants. The combination of the automatic shoulder belt and seat bottom in the subject vehicle was intended to meet this requirement. Because the lap belt had to be fastened manually by the occupant, the lap belt was not part of the passive restraint system. However, because the seat bottom failed, the restraint system failed to protect the occupant and instead caused severe injury.