姚佼 徐洁琼 惠致富
摘 要:过饱和状态是交通需求大于道路通行能力的状态,如对其无法有效识别,极易演变为排队溢出、甚至死锁等严重威胁路网运行效率的状态。文章通过对过饱和交通状态的分析,对各影响因素进行了水平划分,设计了各种影响因素不同水平组合的正交试验,并通过微观仿真软件VISSIM完成了相关的仿真试验。最后,通过相关案例的极差分析,给出了各影响因素对过饱和交通状态影响的排序,通过方差分析的F检验,认为场景特性、交叉口间距、大车比例是对过饱和交通状态最为显著的影响因素。
关键词:交通工程;过饱和交通状态;正交试验;极差分析;方差分析
中图分类号:F570 文献标识码:A
Abstract: Oversaturated traffic is the status that traffic demand is greater than the capacity of the road. If it's not identified effectively in time, the traffic status will easily evolve to queue spillback, or even worse gridlock, which will threaten the efficiency of the road network seriously. Based on the analysis of oversaturated traffic status, we first divided its impact factors into different levels, and then orthogonal test with combination of different level of different impact factor was designed, which was implemented in micro traffic simulation software VISSIM. Finally, from the case study, we got the rank of impact factors of oversaturated traffic status via range analysis, and moreover, through variance analysis, we concluded that scenario characteristics, intersection spacing, and truck ratio are the most remarkable impact factors of oversaturated traffic status.
Key words: traffic engineering; oversaturated traffic status; orthogonal experiment; range analysis; variance analysis
0 引 言
在现有交通设施供给相对稳定的情况下,城市交通需求的不断增加,路网交通流状态逐步从畅通到临界饱和,到过饱和,再到排队溢流,最终向路网死锁演变恶化。过饱和状态是交通需求超过通行能力的状态[1-2],处于整个路网交通流状态演化链的中间,属于城市交通管理中较难处理的交通状态之一,对其处理不当,极易带来多米诺骨牌效益,因此,抓住关键影响因素,对其快速准确的辨识,进而采取相应控制策略,可以防患于未然,有效降低溢流、瘫痪等路网交通流状态恶化发生的概率[3-5]。
对于过饱和交通状态的辨识,交叉口层面主要基于停车线和上游出口的检测器,进行相关的参数估计[6],如Akcelik等基于交通流到达驶离模型对过饱和的排队长度进行估计[7],金凤等在此基础上考虑车辆到达和交叉口影响建立了延误和排队模型[8];……