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.

防护型自行车道（Protected Bike Lanes，又称Cycle Tracks）在全国范围内的普及度持续攀升。尽管已有研究证实防护型自行车道具备多项优势，包括提升骑行安全性、扩大不同骑行群体的出行规模，但学界与业界仍持续担忧：当自行车与机动车在交叉口重新合流时，二者可能发生冲突。其担忧的逻辑在于：经过一段隔离骑行时段后，机动车驾驶员更难预判并留意到自行车的出现。
本研究探讨了完全隔离的骑行环境向混合交通环境转变，以及反向转变时，机动车驾驶员的行为变化。本研究的目标在于评估：特定路段-交叉口组合的交通处理方案，是否能够提醒驾驶员注意自行车的存在，进而促使驾驶员在右转前留意自行车，以减少潜在的右转钩挂冲突（right-hook conflicts）。
本研究采用驾驶模拟实验方法，记录了在不同路段与交叉口的自行车基础设施配置场景下，右转机动车驾驶员的驾驶表现。本实验设计包含两类自行车道与两类交叉口构型：分别为普通自行车道与防护型自行车道，以及设置直行自行车道的交叉口与防护型交叉口。
实验结果表明：道路上出现自行车以及设置防护型自行车道，均会降低路段的平均行驶速度。此外，当采用非防护型交叉口设计时，道路上出现自行车会显著降低交叉口的平均车速。研究还发现，道路上出现自行车会显著影响受试者在交叉口进口道的扫视行为：无论采用何种交叉口构型，更多驾驶员会主动进行右侧扫视。此外，相较于普通自行车道场景，受试者在设置防护型自行车道的路段行驶时，更不容易主动扫视自行车。
本研究可为自行车基础设施的规划决策提供参考，助力实现更安全的多模式交通运营。