Speed choice and hazard perception in complex urban road environments with and without on-street parking.

Speed choice and hazard perception in complex urban road environments Jessica Edquist, Christina M. Rudin-Brown, Michael G. Lenné – Monash University Accident Research Centre Crash risk varies across roads within the same speed zone. There may be environmental factors not currently captured in the speed limit setting process that, if taken into account, would improve the safety of some higher-risk roads. To achieve this aim, it is necessary to understand how drivers’ travel speeds and other risk-relevant behaviours are affected by features of the road environment. The present study examined the extent to which drivers’ speed choice and hazard perception ability are affected by one common feature of urban road environments: on-street parking. Twenty-nine participants drove a simulated urban commercial route with no parking bays, empty parking bays, and parking bays occupied by cars. While driving they performed a safety-relevant peripheral detection task. Each environment also included an unexpected event in which a pedestrian suddenly crossed the road in front of the subject vehicle. Vehicle speeds were slower in the presence of occupied on-street parking bays compared to the other two environments; however, the speed reduction was insufficient to compensate for observed impairments in drivers’ hazard perception and slower response to the pedestrian in this condition. Results suggest that drivers modify their travel speed based on perceived workload, but this modification does not accurately offset the increased visual demand of a complex environment. This mismatch may explain the higher crash risk associated with on-street parking. Implications for policy are discussed.