Using Simulation to Assess Conflicts Between Bicyclists and Right-Turning Vehicles

Protected bike lanes, or cycle tracks, are increasing in popularity across the nation. However, despite the documented benefits of protected bike lanes, including safer cycling and increased ridership among differing populations of bicyclists, there remain ongoing concerns about potential conflicts between bicycles and vehicles when they merge back together at an intersection. The fear is that following a period of separation, drivers are less likely to anticipate and scan for the presence of bicycles. This research examines how transitions from fully separated to mixed-traffic environments and vice versa affect driver behavior. The goal is to assess whether certain segment-intersection treatment combinations can alert drivers of the presence of bicyclists and thus encourage them to scan for bicyclists prior to a right turn, reducing potential right-hook conflicts. Driving simulation is utilized in this study, and driver performance for rightturning vehicles is recorded under the presence of various bicycle infrastructure treatments along segments and at intersections. The experimental design includes two types of bike lanes and two intersection configurations, namely conventional and protected bike lanes and intersections with through bike lanes and protected intersections. Results show that the presence of the bicyclist as well as the presence of protected bike lanes reduce average speed on the segment. Additionally, the presence of the bicyclist significantly reduces the intersection speed when non-protected intersection design has been implemented. The presence of the bicyclist was also found to significantly affect participants’ glancing behavior at the intersection approach, triggering more of them to place a right glance regardless of the intersection configuration. In addition, participants were found to be less likely to glance for the bicyclist when riding on a segment with protected bike lanes compared to scenarios with conventional bike lanes. This research can be used to guide decisions on bicycle infrastructure implementation for safer multimodal operations.