信号交叉口右转机动车与行人冲突运动模型

在一些信号交叉口,右转机动车的转弯行为不受信号控制,容易与过街行人发生冲突。现有冲突研究的内容多为冲突判别和冲突分级研究,对人车冲突运动过程研究相对较少。为减少交通冲突,提高行人过街安全性,提出一种新的右转机动车与行人冲突运动过程的仿真模型。研究右转车辆的决策过程,分析人车冲突机理。建立人车冲突模型,依据实际调查所获得的车辆速度和可接受间隙数据,对模型参数进行标定。对模型进行仿真分析,通过比较冲突时间、后侵占时间、安全减速度、间距时间4个冲突严重性指标,选择后侵占时间(PET)这一评价指标进行安全评价。仿真得到的车辆速度和 PET 数据与调查得到数据相比误差不超过5%,验证了模型的有效性。通过灵敏度分析,小交叉口 PET 提高了10%,说明小交叉口有助于降低冲突的严重性。 

A Conflict Model Involving Right-turning Vehicles and Cross-walking Pedestrians at Signalized Intersections

Normally,the right-turning movement of vehicles at signalized intersections is not controlled.Thus, there are potential risks of conflicts between the right-turning vehicles and cross-walking pedestrians.Current studies ad-dressed on the identification and classification of such conflicts,no theoretical model is proposed to analyze such processes of conflicts.With the purpose to reduce conflicts and improve safety of pedestrians,a new simulation model to describe the conflict processes between right-turning vehicles and cross-walking pedestrians is proposed in this study.The decision-making process of right-turning vehicles is studied.Then the mechanism of conflicts between vehicles and pedestrians is analyzed.Finally,a vehicle-pedestrian conflict model is established.Meanwhile,the coefficients for this model are calibra-ted using actual data including vehicle speed and gap acceptance.A simulation study is then conducted to optimize the measurements for safety evaluation:time-to-collision (TTC),post-encroachment time (PET),safety braking decelera-tion,and gap time.The results reveal that PET is the most significant measurement to evaluate vehicle-pedestrian con-flict.The accuracy analysis results show that the deviation of vehicle speed and PET between simulation and actual data is less than 5%,which indicates the validity of this model.An implementation of sensitivity analysis shows that PET of small size intersections increases 10% compared with large size of intersections,which indicates that small intersections have the advantage to reduce the severity of conflicts.