The Austroads in-depth case control study of motorcycle crashes in NSW: causal relationship findings

To develop effective countermeasures there is a need for detailed understanding of risk factors influencing crash involvement and injury outcomes among motorcyclists. To this end, Austroads commissioned a study of motorcycle crashes in NSW. The aims of this study were to: 1. Examine causal relationships between human, vehicle, road and other environmental factors and motorcyclists in serious injury crashes, and 2. examine the influence of the total system on the injuries sustained by seriously injured motorcyclists. This paper summarises the causal relationship findings from this study. A case-control in-depth investigation approach was coupled with expert multidisciplinary review of crashes to achieve these aims. Data collection occurred between August 2012 and July 2014 and followed the ANCIS protocols. The final case-control sample included 99 crashed riders and 336 control riders. The results indicate riders using sports motor cycles have greater odds of serious injury crash involvement than riders using other motorcycle types. However the elevated crash risk associated with sports bikes was more prominent among older riders. Riding an unfamiliar motorcycle also significantly increased the odds of being in the crash sample. Another novel finding is that riders who rode the crash location daily had seven times the odds of being in the crash sample than the control sample. However, the mixed methods used in this study also identified route unfamiliarity as a contributory factor, suggesting a non-linear relationship between familiarity and crash risk. Protective factors were increased age of the rider, and use of protective clothing.