System failures and extreme behavior in fatal and injury crashes in South Australia

Within the road system, there are compliant road users who may make an error that leads to a crash, indicating a "system failure." There are also road users who deliberately take risks and engage in dangerous or "extreme" behavior that leads to a crash. This study aims to assess the relative contribution of system failures and extreme behavior to guide the development of future strategies and interventions needed to create a safe system and prevent road trauma.

This study used the same methodology as Wundersitz et al. to provide an update on the relative contribution of system failures and extreme behaviors in more recent crashes. Two samples were used for the study: 157 fatal crashes from Coroner's investigation files and 235 injury crashes from in-depth crash investigations conducted by the Center for Automotive Safety Research.

Consistent with previous findings, the results indicated that the majority of fatal (70%) and injury crashes (93%) in South Australia were attributable to failures within the road transport system. In almost half of the fatal crashes and 72% of injury crashes, road users were fully compliant (i.e., no illegal behaviors). A comparison of the relative contributions over time revealed that the proportion of extreme behaviors in fatal crashes has decreased, which may be, at least partly, attributable to a reduction in alcohol-related crashes within South Australia.

Overall, the findings suggest that strategies continuing to focus on system wide improvements to the road transport system such as providing safe road infrastructure (e.g., side and center barriers) and the accelerated uptake of safe vehicle technologies (e.g., lane keeping technology, autonomous emergency braking) can be expected to be effective in reducing the incidence and severity of a large proportion of fatal and serious injury crashes. For more extreme behaviors, greater control of road user behavior may be required through the increased use of vehicle technologies and more holistic social health initiatives.