道路交叉口冲突仿真分析

针对基于事故的安全评价在数量、周期、均值、随机性等方面以及基于现场冲突观测识别在主观性、可靠性、成本、指标全面性等方面存在的问题,提出基于冲突仿真的交叉口安全预评价分析方法:研究利用安全间接分析(SSAM)模型分析冲突的基本原理和冲突时间(TTC)、遭遇时间(PET)等分析指标的计算方法;以及利用VISSIM仿真软件进行冲突仿真分析应注意的策略。以邢台市某道路交叉口安全改善方案为例,进行改善前后冲突仿真的比较分析。研究结果表明,改善后在通行效率显著提升的同时,交叉、追尾、车道变换冲突的数量均显著减少,TTC值有所增加,说明改善后安全程度有所提升。笔者提出的方法和案例应用为道路交叉口改善措施的安全预评价提供了一种分析途径和有益借鉴。

Traffic Conflict Simulation Analysis for Urban Road Intersection

Aimed at the typical problems in the aspects of number,cycle,mean value and randomness of intersection accidents safety assessment and the ones in the aspects of subjectivity,reliability,costs and index completeness of site survey recognition of traffic conflict,a pre-assessment method based on traffic conflict simulation is put forward.Basic theories of traffic conflict techniques by using SSAM(Surrogate Safety Assessment Model),calculation method of TTC(Time to Conflict),and PET(Position Encroachment Time) are studied,and simulation strategies during the process of safety analysis are also researched by utilizing VISSIM software.In the end,with the improved intersection of Xingtai city in Hebei Province as an example,a comparative analysis of conflict simulation results between before and after improvement is carried out.The result shows that the number of crossing conflict,rear-end conflict and lane-change conflict decreases sharply,and corresponding TTC Value increases in some extent with the improving of operation efficiency,which indicates that there is an enhancement of safety after the intersection being improved.The method and case study provides a useful approach and is beneficial for evaluating the safety effect of countermeasures.