Abstract: In view of the deterioration of traffic situation caused by sudden traffic accidents on expressways, three scenarios were set according to the distance between the accident location and the upstream entrance ramp. Firstly, the traffic capacity of bottleneck in different scenarios were analyzed. Then, based on the feedback control model, the vehicle was subject to hierarchical speed limit control and the setting position of variable speed limit control in low-speed section in different scenarios was discussed. Variable speed limit (VSL) control methods under three scenarios were constructed respectively. According to the principle of cell transmission model (CTM), the secondary development simulation of VISSIM was carried out to verify the control performance of each scenario under different traffic conditions. The results show that the proposed variable speed limit control method can effectively improve the outflow flow of bottleneck section during the accident, homogenize the density between road sections, delay the occurrence time of congestion and reduce the duration of congestion, and effectively reduce vehicle delays and parking times. In scenario 2, the vehicle delays and stops are reduced by 46% and 14% respectively, when the input flow is 6 000 veh/h.

Key words: traffic engineering; highway; accident bottleneck; variable speed limit control; feedback control; step-by-step speed limit

摘要： 针对高速公路突发交通事故而导致交通态势恶化的问题，根据事故位置与上游入口匝道的距离分为三种场景，分析不同场景下瓶颈的通行能力，以反馈控制模型为基础，对车辆进行分级限速控制，并探讨了不同场景下可变限速控制低速段的设置位置，分别构建了三种场景下的可变限速控制方法。根据元胞传输模型原理对VISSIM进行二次开发仿真，验证每种场景在不同的流量条件下的控制性能。研究结果表明：提出的可变限速控制方法能够有效提高事故期间瓶颈路段的流出流量，使路段之间的密度均匀化，延迟拥堵的出现时间和减少拥堵持续时间，有效减少车辆延误和停车次数；场景二在输入流量为6 000 veh/h的条件下所减少的车辆延误和停车次数分别为46%、14%。

关键词: 交通工程；高速公路；事故瓶颈；可变限速控制；反馈控制；分级限速