Compressive Neck Injury and Its Relationship to Head Contact & Torso Motion During Vehicle Rollover

Previous literature has shown that serious neck injury can occur during rollover events, even for restrained occupants, when the occupant’s head contacts the vehicle interior during a roof-to-ground impact or contacts the ground directly through an adjacent window opening. Confusion about the mechanism of these injuries can result when the event is viewed from an accelerated reference frame such as an onboard camera. Researchers generally agree that the neck is stressed as a result of relative motion between head and torso but disagree as to the origin of the neck loading. This paper reviews the principles underlying the analysis of rollover impacts to establish a physical basis for understanding the source of disagreement and demonstrates the usefulness of physical testing to illustrate occupant impact dynamics. A series of rollover impacts has been performed using the Controlled Rollover Impact System (CRIS) with both production vehicles and vehicles with modified roof structures. Data from these tests were analyzed in both the vehicle reference frame and an inertial reference frame to demonstrate the neck injury mechanisms. The results of these tests show that neck loading was fundamentally a result of torso augmentation rather than roof deformation.