Bicycle crash contributory factors: A systematic review

• Bicycle crash causation is a critical area for road safety research. • We conducted a systematic review of bicycle crash contributory factors. • Most studies focus on the road environment, cyclist infrastructure, and cyclist and driver behaviour. • Few studies examined causal relationships between contributory factors. • Gaps exist in the knowledge base regarding bicycle crash causation. There is a growing body of road safety research that seeks to identify crash contributory factors beyond road users, their vehicles, and the immediate road environment. Although cyclist safety represents a critical research area, this ‘systems thinking’ approach has received less attention in bicycle crash analysis. This article presents the findings from a systematic literature review which aimed to synthesise the peer reviewed literature regarding bicycle crash contributory factors (defined as factors which play a contributory role in bicycle crashes, as opposed to risk factors which are factors which may increase the probability of crashes). Crash contributory factors were extracted from included articles and mapped onto a systems thinking framework comprising seven hierarchical road transport system levels. The findings show that a majority of the included studies identified contributory factors relating to the road environment, cycling infrastructure, and cyclist and driver behaviour. No studies identified contributory factors outside of cyclists and road users, bicycles and vehicles, and the road environment and few specifically examined causal relationships between contributory factors. It is concluded that there are gaps in the knowledge base regarding the broader transport system features that play a role in bicycle crashes and how contributory factors interact to create crashes. We argue that more expansive research into the systemic factors involved in bicycle crashes is required and that initial work should focus on the development of new data sources and analysis methods.