车流随机性对协调系统控制效果的影响
Influence of traffic randomness on control effect of coordination system

为了提高协调系统运行的稳定性及控制效果，针对车流随机特性，采用理论分析和仿真计算相结合的方式，探讨车流速度波动和车流到达率波动2个因素对协调系统控制效果的影响机理。理论分析中，将变动的车流速度转化为区间数形式，根据单向协调相位差求取公式，得到理想相位差的变动区间；根据相位清空可靠度计算公式，得到车流到达率波动与最佳周期、协调相位绿灯时间、车均延误时间、最大排队长度等的解析关系，并进一步借助双向协调系统中求取相位差的数解法，得到关于车流到达率波动方差的相位绿时差。仿真分析中，利用MATLAB与VISSIM搭建仿真平台，选取2个几何线形规则的信号交叉口，制定模拟协调控制方案，选取仅改变车流速度、仅改变车流到达率、同时改变车流速度和到达率这3种情况进行仿真，以车均停车时间、平均排队长度、车均停车次数、车均延误时间为指标，评价其对协调系统控制效果的影响。研究结果表明：车流速度波动方差、车流到达率波动方差与控制效果均呈正相关关系，车流速度波动的影响大于车流到达率波动的影响，两者同时波动时不是简单的叠加关系，而是相互抵消影响，其控制效果介于2种情况之间；仅车流到达率波动的情况下，协调相位双侧车流到达率波动时，控制效果优于单侧车流到达率波动；车流处于自由流与拥挤流之间切换状态时，控制效果优于拥挤流状态，劣于自由流状态。
In order to improve stability and control effect of coordination system, the influence mechanisms of traffic speed fluctuations and traffic arrival rate fluctuations on control effect of coordination system were discussed, aiming at traffic randomness through theoretical analysis and simulation calculation. In theoretical analysis, fluctuant traffic speed was transformed into interval numbers, change interval of idea phase difference was obtained based on calculation formula of one-way coordination phase difference. Analytical relationships among traffic arrival rate fluctuation and optimal cycle, coordination phase green time, average traffic delay time, maximum queue length were gained based on calculation formula of phase empty reliability. Furthermore, based on numerical method of two-way coordination system phase difference, the phase green time-difference with respect to traffic arrival rate fluctuation variance was obtained. In simulation analysis, simulation platform was established by MATLAB and VISSIM. Two signal intersections with regular geometric alignment were chosen, and simulation scheme of coordination control was made. With the indexes consisted of average traffic parking time, average queue length, average traffic stops, average traffic delay time, influences of control effect of coordination system were evaluated in three situations that considering traffic speed fluctuations only, considering traffic arrival rate fluctuations only and considering both of which to make simulation. The results show that control effect is positively related to variance of traffic speed fluctuation and variance of traffic arrival rate fluctuation. The effect of traffic speed fluctuation is greater than that of traffic arrival rate fluctuation, both simultaneous fluctuation is not a simple superimposition relationship, but offset each other, so that control effect is between the two cases. In the case of only traffic arrival rate fluctuation, control effect of coordination phase bilateral