过饱和状态下的单交叉口最小延误信号周期模型
Signal cycle model for minimum delay at oversaturated isolated intersection

由于现有单交叉口信号配时方法主要适用于低饱和交通状态, 本文以过饱和交通状态作为研究对象, 利用定数理论分析了信号交叉口进口道的车辆到达与驶离规律, 建立了信号周期与延误时间之间的数学模型, 推导了单交叉口最小延误的信号周期计算公式. 以某个四相位交叉口为例, 针对3组不同流量比的过饱和交通状态, 分别获取了延误时间与信号周期之间的变化曲线, 计算了最小延误所对应的最佳信号周期, 并利用VISSIM微观交通仿真软件, 仿真得到了3组不同流量比情况下的延误时间. 仿真结果表明: 在各组流量比设置下, 延误时间的理论计算值与仿真实验值相一致, 有效验证了该模型的准确合理性, 为解决过饱和状态下的交叉口信号配时优化问题提供了理论指导依据.
The existing signal timing methods for isolated intersection are mainly suitable for low saturation traffic state. Taking oversaturated traffic state as the research object, we develop a mathematical model between the signal cycle and the delay by analyzing the arrival-departure rule of vehicles at signalized intersection entrance with the deterministic theory. Then, the signal cycle formula at isolated intersection is deduced for minimal delay. Taking a four-phase intersection for example, we plot the changing curves between the signal cycle and delay; and the optimal signal cycles are found respectively for the three oversaturated traffic conditions that have different flow ratios. Finally, the delay under each traffic flow ratios was obtained by using VISSIM micro-simulation software. The simulated result shows that the delay from theoretical calculation coincides well with that of simulation under different flow ratios, validating the accuracy and rationality of the model. This provides a theoretical basis for solving signal timing problem at oversaturated intersection.