Abstract: Aiming at the on-ramp traffic signal control of urban expressway, based on the traffic wave theory, this paper analyzed the spatio-temporal characteristics of the traffic flow inside the intersection, and described the queuing process of the traffic flow on expressways and that on ramps. In addition, an optimization model of on-ramp traffic control of urban expressway is established with the objective of minimizing the average traffic delay at the intersection, and taking the green light time assignment and signal cycle of urban expressway and on-ramp as the optimization parameters. Moreover, the model is verified by a numerical example. The research result shows that all the remaining passable time should be allocated to expressways to minimize the total traffic delay at the intersection, when the green light time of expressway and that of the ramp meet the minimum requirements and there is still excess effective passable time (the difference between signal cycle and cycle lost time). The average vehicle delay has been reduced from 16.76s to 13.18s in the expressway on-ramp intersections, with a decrease of 21.36%, and the maximum queue length on the on-ramp has been shortened from 48.82m to 33.28m, with a decrease of 31.83%.

Key words: urban traffic, signal control, traffic flow wave theory, urban expressway, on-ramp control

摘要： 针对城市快速路入口匝道的信号灯控制方案，借助车流波动理论，分析了该类交叉口内部的车流运行时空特性，描述了快速路、入口匝道上的车流在交叉口的排队过程，以交叉口车流总延误最小为目标，快速路与入口匝道的绿时分配以及信号周期为参数，建立了城市快速路入口匝道交通控制优化模型，并通过一个实例对优化模型和求解算法进行了验证。研究结果表明：当快速路及匝道绿灯时间均满足最低要求而交叉口有效通行时间（信号周期与周期损失时间的差值）仍有富余时，应将富余的可通行时间分配给快速路，以使得交叉口车流总延误最小。快速路入口匝道交叉口的车辆平均延误由优化前的16.76 s下降至13.18 s，同比下降21.36%；匝道最大排队长度由48.82 m缩短至33.28 m，同比下降31.83%。

关键词: 城市交通, 信号控制, 车流波动理论, 城市快速路, 入口匝道控制