Timing of Head-to-Vehicle Perimeter Contacts in Rollovers

During a rollover accident the position of an occupant within a vehicle at the time of vehicle-to-ground contact affects the occupant's injury potential and injury mechanisms. During rollovers, the accelerations developed during the airborne phases cause an occupant to move away from the vehicle's center of mass towards the perimeter of the vehicle. The occupant is already in contact with vehicle structures during upper vehicle structure-to-ground impacts. The location and extent of the occupant-to-vehicle contacts and the times and locations at which the contacts occur depend upon a variety of factors including occupant size, initial position in the vehicle, restraint status, vehicle geometry, and rollover accident parameters.

Onboard and offboard video of existing dolly rollover studies, specifically the “Malibu” studies, were examined to quantify the motion of the occupants' heads and determine the timing and locations of head contacts to the vehicle perimeter. Quantitative analysis of onboard video was performed to determine the trajectory of each occupant's head relative to the vehicle interior. The roll rate of the vehicle was determined using offboard video. The head trajectory and time of head contact were identified. The head trajectory and the timing and locations of head-to-vehicle perimeter contacts were affected by occupant and vehicle parameters such as seating position (near or far side of rollover) and restraint status.