The Influence of Body mass index and weight on injury severity in motor vehicle crashes

Vehicle safety testing standards in Australia list dummies of three specific proportions to represent adult drivers and passengers in laboratory crash testing: the 50th percentile male, 5th percentile female and the 95th percentile male. However, only the historically ascertained 50th percentile male dummy is required for test compliance. Given the vastly differing physical proportions of adult vehicle occupants across the population, it is conceivable that they will suffer different injuries in a motor vehicle crash relative to their differing physical proportions. The aim of this study was to investigate the influence of occupant Body Mass Index1 (BMI) and body weight on the injury severity of front seated adult occupants in frontal motor vehicle crashes. This is the first study using real-world Australian data to investigate this issue. In-depth crashed vehicle data collected by the Monash University Accident Research Centre (MUARC) were analysed. Differences in injury severity were compared against BMI and weight and analysed against
other relevant variables including measurements of crash severity. Multivariate logistic regression analysis showed the risk of moderate to critical injury (Abbreviated Injury Scale – AIS2+ injury) was significantly related to lower occupant BMI, and higher equivalent barrier speeds of the crashed vehicle. This paper outlines the importance for vehicle safety testing standards and injury prevention strategies to consider the
needs of adult occupants who differ from the designated test standard physiological dimensions.