Passing distance, speed and perceived risks to the cyclist and driver in passing events.

Introduction: Up to 38% of crashes between motor vehicles and cyclists involve overtaking and close passes, contributing to a fear of cycling for both current and potential riders. Consequently, most research has focused on the cyclist's perceptions of risk in passing events; but the driver's perceptions may be more influential determinants of passing distances and thus, objective crash risk.

Method: In an online cross-sectional survey, participants viewed 24 video clips of naturalistic passing events (external view akin to being a following driver) on urban roads in Queensland, Australia and judged distance and safety for both the portrayed cyclist and the passing driver. The passing events were filmed at a low-speed site (40 km/h speed limit) and a high-speed site (70 km/h speed limit).

Results: The 240 cyclist participants were more likely to rate the pass as unsafe for the portrayed cyclist than the 71 non-cyclist participants. Narrow passing distance, parked vehicles, oncoming vehicles, and higher motor vehicle speeds were significant predictors of rating the pass as unsafe for the portrayed cyclist and the passing driver. In addition, female participants were more likely to rate the pass as unsafe for the driver. Participant age, attitudes toward cyclists and frequency of passing cyclists did not significantly affect safety judgments.

Discussion: Traffic and roadway characteristics largely underlie perceptions of safety for both the cyclist and the driver when passing, even after accounting for passing distance. External, objective factors are more important than attitudes toward cyclists.

Practical Applications: Attempts to improve the subjective and objective safety of passing events may be more successful if their focus is on modifying traffic and roadway characteristics, rather than attempting to change drivers' attitudes toward cyclists. Limitations on motor-vehicle passing speed should be incorporated as part of safe bicycle passing laws.