Head and Thorax Injuries in Rollover Crashes

Rollover crashes are one of the most dangerous passenger vehicle crash modes accounting for 24% of occupant fatalities in Australia for the period 2004 to 2005. Ejected occupants and an inherent lack of strength in vehicle roof structures are causal to the high serious injury and fatality rates observed in this crash mode. US studies have focussed on spinal and neck injuries. However, recent work published by the authors has identified that head and chest injuries are more prominent than neck injuries to contained occupants. It is not clear how such injuries occur in terms of a biomechanical mechanism, albeit a proportion of the head injuries have been identified as base of skull fractures. Movement of the restrained occupant in relation to the roof deformation may provide some insight how the head and chest injuries occur. This in turn would assist with establishing which biomechanical injury measures could be used to assess the risk of such injuries in full scale rollover crashworthiness testing. However, little work has been carried out in terms of analysing the different roof crush mechanisms in any detail, particularly in relation to how a crash test dummy could adequately measure the risk of head and chest injury. This paper presents the different roof crash mechanisms and compares them to results from GM Malibu tests and Jordan Rollover System test results along with measurements from the crash test dummies. The issue of what is an appropriate method to measure head and chest injury risk is discussed.