Side Impact CrashesåFactors Affecting Incidence and Severity: Review of the Literature

Abstract

Many traffic crashes are side impact collisions resulting in significant death and injury. A review was conducted of the evidence of driver, road, and vehicle characteristics affecting either the risk of occurrence or the severity of injury in such crashes for papers published from 1996 to early 2003. For drivers, evidence was found of increased crash risk or injury severity only for age and age-related medical conditions (e.g., dementia). Traffic roundabouts and other traffic control devices—stop signs, traffic lights, and so on—had mixed results; traffic controls were better than no controls, but their effectiveness varied with circumstance. Most vehicle characteristics have had little or no effect on crash occurrence. Antilock braking systems (ABS) in the striking vehicle had been anticipated to reduce the risk of crashes, but so far have demonstrated little effect. The primary emphasis in vehicle design has been on protective devices to reduce the severity of injury. Disparity in the size of the two vehicles, especially when the struck vehicle is smaller and lighter, is almost a consistent risk factor for occupant injury. The occupants of light trucks, however, when struck by passengers cars on the opposite side, were at higher risk of injury. Wearing seat belts had a consistently protective effect; airbags did not, but there were few studies, and no field studies, of lateral airbags found. Of all the characteristics examined, vehicle design, including occupant restraints, is the most easily modified in the short term, although road design, traffic control, and the monitoring of older drivers may also prove effective in reducing side impact crashes in the longer term.