Side Impact and Side Swipe

In a frontal or rear impact, deformation of the vehicle absorbs significant collision energy and reduces the forces transmitted to the occupant compartment. Other features (e.g., energy-absorbing steering column, padded instrument panels) also absorb energy.

Fig. 66. Side collision; intrusion of driver's side door. (Courtesy of Road Safety and Motor Vehicle Regulation Directorate, Transport Canada.)

In contrast, the side of a vehicle has less crushable structure (Fig. 66). As a result, substantial forces are transmitted in less severe crashes directly to the occupant compartment, and intrusion is common, increasing the risk of injury (490,646-649). Being in a struck vehicle that has less mass than the striking vehicle increases this risk (648). A restraint system is less effective if there is intrusion (648).

In a side impact collision, an occupant moves laterally toward the side of impact and forward, if that is the direction in which the target vehicle was moving initially. Contacts with the side window, B-pillar, and interior door are common in near-side impacts (Fig. 18; refs. 4 and 650). Occupants, particularly if unrestrained, can be completely or partially ejected, contacting the ground, impacting vehicle, or a fixed object (Fig. 67; ref. 651). Serious head injuries can result if there is intrusion (651). In far-side impacts, unrestrained occupants can be displaced across the vehicle and injure restrained occupants (652,653). Restrained occupants sitting on the far side can also contact the opposite side interior and other occupants or be injured by their seat belts (651,654). A far-side occupant can come out of the shoulder part of a restraint (651). For individuals in far-side collisions, the presence of a near-side occupant mitigates injuries from contact with the opposite side interior (651,654).

Injuries from side impact collisions have a different pattern from those caused by frontal impacts. Head, neck, chest, and abdominal injuries are common in near-side impacts (4,647). Intrusion of the vehicle roof or B-pillar often leads to severe trauma directly to the head, a major contributor to death causation (650,655). Lateral impact to the torso is very common, producing multiple rib and pelvic fractures on the side of

Fig. 67. Side collision; intruding truck. Arrows indicate head contact by motor vehicle occupant. (Courtesy of Road Safety and Motor Vehicle Regulation Directorate, Transport Canada.)

intrusion (495). Severe thoracic, abdominal, and pelvic visceral trauma occurs (490,646). Head and torso injuries dominated in one study of far-side collisions (654).

A side-swipe crash occurs when a moving vehicle glances off another vehicle or fixed object. Injuries to occupants occur when there is either intrusion into the passenger compartment or significant energy transfer through the stiff vehicle structure. These injuries resemble those of the near-side impact crashes.

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