快速路上匝道瓶颈路段异质交通流演变规律

Heterogeneous Traffic Flow Evolution Rule in Expressway On-ramp Bottleneck Section

为了掌握快速路瓶颈路段异质交通流的演变规律,以缓解交通拥堵,本文以快速路上匝道瓶颈路段为研究对象,构建了考虑安全距离的改进NaSch上匝道模型,利用数值仿真,对不同场景交通流演化过程进行系统性研究。仿真结果显示:在不同条件下,异质交通流中自动驾驶车辆比例的增加对瓶颈路段交通运营状态影响结果各异。在自由流阶段,自动驾驶车辆比例的增加对快速路瓶颈路段运营通行能力的增加无显著影响,自动驾驶车辆比例取0.9时,瓶颈路段运营通行能力反而降低了2.48%;在交通拥堵状态下,当异质交通流中自动驾驶车辆比例达到0.7及以上时,才有助于交通拥堵的消散,且其临界值随交通拥堵状态程度的提高而增大;当交通密度达到100 veh/km以上时,自动驾驶车辆比例的增加无法实质性改善瓶颈路段交通拥堵状态。研究结果可为异质交通流环境下的快速路上匝道瓶颈路段的治堵策略提供理论依据。

To grasp the evolution rule of heterogeneous traffic flow on expressway bottleneck section and alleviate traffic congestion,the paper takes expressway on-ramp bottleneck section as study object.An improved NaSch on-ramp model considering safety distance was constructed,and the evolution of traffic flow in different scenarios was systematically studied by numerical simulation.The simulation results show that the increase of the proportion of autonomous vehicles in heterogeneous traffic flow has different effects on the transit operation of the bottleneck section.When the proportion of self driving vehicles is 0.9,the traffic capacity of the merging section was reduced by 2.48%in the free flow phase.When the proportion of self driving vehicles in heterogeneous traffic flow reaches 0.7 or more in the stage of traffic jam,it will help to dissipate the traffic congestion,and its critical value will increase with the increase of the degree of traffic congestion.When the traffic density reaches more than 100 veh/km,the increase of the proportion of self driving vehicles can not substantially improve the traffic congestion in bottleneck sections.The research results can provide theoretical support for the congestion control strategy on the expressway on-ramp bottleneck section.