Abstract: Aiming at the problems of reduced traffic efficiency, increased vehicle delay and reduced overall service level in expressway confluence area, an optimization model of vehicle flow density in expressway confluence area based on variable speed limit (VSL) and lane change control was proposed. Firstly, lane change control provided lane change suggestions for connected vehicles by predicting bottleneck capacity and traffic demand, to optimize the traffic flow density of upstream of the merging area and reduce the impact of the decline of bottleneck capacity. Secondly, the VSL before correction was determined based on the bottleneck capacity of the merging area under lane change control and the traffic flow density of the ramp. Thirdly, the feedback VSL control based on cell transmission model was used to the upstream flow of traffic bottleneck in real time to ensure that the density of lane changing area converged to the optimal equilibrium point, and the modified VSL was obtained. Finally, the cell transmission model was selected as the basic traffic flow model. For the lane change control in the confluence area, the meso multi-lane cell transmission model was adopted to simulate the lane change behavior of the main line in the confluence area and the impact of lane change control on the traffic flow operation in the confluence area. The simulation results show that compared with no control scheme and VSL control scheme, the average travel time of collaborative control is reduced by 58.55% and 35.68% respectively, and the average flow is increased by 9.09% and 2.35% respectively. Collaborative control has significantly improved traffic efficiency and traffic safety.

Key words: intelligent traffic; freeway; variable speed limit; lane change; CTM model

摘要： 针对高速公路合流区通行效率降低、车辆延误增加、整体服务水平下降等问题，提出了一种基于可变限速和换道控制的高速公路合流区车流密度优化模型。首先，换道控制通过预测瓶颈容量和交通需求为联网车辆（CAVs）提供变道建议，优化合流区上游的车流密度，减少瓶颈容量下降的影响；其次，基于换道控制下的合流区瓶颈容量以及匝道的交通流密度，确定修正前的可变限速值；再次，利用基于细胞传输模型的反馈进行变限速控制，实时控制交通瓶颈上游流量以保证换道区密度收敛到最优平衡点，得到修正后的可变限速值；最后，选择元胞传输模型作为基础交通流模型对合流区进行换道控制，采用中观多车道元胞传输模型模拟合流区主线换道行为及换道控制对合流区交通流运行的影响。仿真结果表明：与无控制方案和VSL控制方案相比，协同控制的平均旅行时间分别降低了58.55%、35.68%，平均流量分别提高了9.09%、2.35%，协同控制在通行效率、交通安全方面均有明显改善。

关键词: 智能交通；高速公路；可变限速控制；换道控制；CTM模型