Delay Modeling On Pedestrian-vehicle Conflict At Crosswalks In Urban Street

Mixed traffic flow is the major pattern on urban road network in developing countries. In recent years, many scholars both home and abroad have done continuous in-depth study on mixed traffic flow issues, which have added many new research topic for the field of traffic engineering. As an pedestrian crossing infrastructure, crosswalk is the important region of conflict where pedestrians and vehicles are "fighting" for the right-of-way. Meanwhile, the interference and conflict of pedestrians and vehicles in the crosswalks is affecting the operational efficiency of surrounding road network and associated sections. Therefore, it is necessary to conduct a comprehensive in-depth study on the behaviors (in particular, acts of interference and conflict) of pedestrians and the vehicles in the crosswalk area.Basing on summarization of the domestic and foreign research on delay of pedestrian-vehicle conflict, combined with the actual situation in Beijing, three pedestrian-vehicle delay models were built and the occurrence and development of interference behavior of pedestrians and vehicles were simulated in crossing area, which provides a new way of the quantitative evaluation of implementation of traffic improvement and optimization measures. The main work and conclusions are as follows.â‘ From the aspects of pace, waiting-time tolerance, critical time interval, crossing facilities, conflict yielding, behavior characteristics of the pedestrians and the delay of pedestrian-vehicle conflict were reviewed at home and abroad. The main problems including the lack of research on pedestrian collision avoidance distance, the location of pedestrian source, consideration of the adequacy of crossing time, quantitative research on different ways of crossing were point out, and the direction for further study were figured out.â‘¡The scope of the conflict between pedestrian and vehicle in crosswalk areas were conformed basing on conflict zone definition. Based on the types of conflict differentiated by looking direction of pedestrian and analysis of 4 types or 12 categories of conflict scenarios, the principles of conduct were established and pedestrian-vehicle delay model was proposed based on conflict. After the calibration of the relevant parameters, a binary road of dual 4-drive in Beijing was simulated as an example. The results show that the proposed principles of conflict zones and conduct judgement can effectively describe the conflict of pedestrians and vehicles in the crossing areas. According to simulation output data, combining with the conflict model, delays led by pedestrian and vehicle conflicts show a positive correlation between the two flows. In evening peak hours on Friday, the pedestrian average delay is 29.6s/ped and vehcile average delay is 11.0s/veh, when the pedestrian flow reaches 1196 ped/h and vehicle flow reaches 2610veh/h.â‘¢Basing on the volume of crossing paved on the same road, the conflict and yielding behaviour of the pedestrians crossing the street and the vehicles, the affecting factors of the delay of pedestrians and vehicles on road sections were discussed, then 4 scenes of conflict were discussed where 2 crossings were set. Delay models were constructed as pedestrian delay model, vehicle delay model, and pedestrian-vehicle average vehicle delay model based on the location of crossing. One road section in Beijing Xicheng District was simulated, in which a check-up is made between the two constructed models in cases of one and two crosswalks on one section. Simulation results show that in pedestrian-vehicle system, the average pedestrian delay and the average vehicle delay are closely related to the locations of crosswalks in average pedestrian delay model, while the average pedestrian delay is much greater than the average vehicle delay, and the traffic efficiency of single-crosswalk road is lower than the double-crosswalk road with same pedestrian volume.â‘£Based on pedestrian crossing styles (once or twice cross), the behavioral characteristics of pedestrians and non-motor vehicles were analysed, then 3 types of pedestrian yielding behavior and 4 types of vehicle running behavior were discussed. The pedestrian and vehicle delay of once and twice crossing styles on high grade roads and big singnalised intersecton were modeled. After that, the generation process of delay for different pedestrian crossing modes on high grade intersections were analysed, and several models were built, including pedestrian crossing delay model, vehicle delay model, pedestrian-vehicle system average delay model based on the crossing mode of road and intersection. The delay of once and twice crossing facilities of a singlised trunk and intersection in Beijing were studied. The conclusion is that the pedestrian-vehicle system delays and road signal timing are closely related and twice-crossing mode on sections and intersections cannot completely avoid conflicts between the pedestrians and vehicles compared to once-crossing mode whereas significantly decreased conflicts. Compared with once-crossing mode, the systematic average pedestrian delay of twice-crossing mode respectively reduces 14.3%/7.4% on road, and more obviously optimized 16.8%/9.5% in the intersection at a.m./p.m. peak hours.