自动跟踪动态临界占有率的匝道协调控制方法
Coordinated control method of ramps based on automatic tracking dynamic critical occupancy

为了解决高速公路主线合流区交通拥挤与入口匝道排队溢出问题,提出了一种入口匝道协调控制方法,依据主线合流区交通状态和入口匝道排队长度设计需要协调控制的匝道个数,以扩大协调匝道组的空间容量,增大截留进入主线交通拥挤区域车辆的能力; 应用实时检测的主线合流区通过量和占有率估计主线动态临界占有率,采用入口匝道调节率自动跟踪主线合流区动态临界占有率的变化,以提高主线通过量; 采用匝道相对排队长度设计启发式规则,以提高入口匝道协调控制能力,防止排队溢出; 以沪宁高速公路G42为仿真背景,应用VISSIM仿真软件,从路网性能、主线合流区交通状态和匝道排队长度三方面对提出方法的控制效果进行评价。计算结果表明:相比于无控制算法,采用控制方法的总行程时间减少约8.44%,路网平均延误减少约62.97%; 采用ALINEA算法的总行程时间减少约2.85%,路网平均延误减少约21.20%; 采用Linked-control算法的总行程时间减少约6.00%,路网平均延误减少约56.17%; 采用控制方法的主线合流区的交通通过量在交通状态突变时增加了540 veh？h-1,且各个匝道之间排队长度更加均衡。可见,提出方法控制效果优良。
In order to solve the problems of traffic congestion in mainline confluence area and the on-ramp queue overspill for freeway, a coordinated control method of ramps was proposed. Based on the traffic statuses in mainline confluence area and the on-ramp queue lengths, the real-time number of coordinated control ramps was determined to improve the capacity of ramp groups and increase the vehicles merging into the bottleneck area of mainline. To improve the capacity of mainline confluence area, the dynamic critical occupancy of mainline was designed by using the real-time detection data of traffic volume and occupancy of mainline, and its variation was tracked by using the on-ramp metering rate. The heuristic rules were designed according to the relative on-ramp queue lengths to enhance the on-ramp coordinated control ability and prevent the on-ramp queue overspill. Based on Shanghai-Nanjing Freeway G42, the freeway network performance, the traffic condition of downstream mainline confluence area and the queue lengths of ramp were computed by using VISSIM simulation software to evaluate the control ability of the proposed approach. Computation result shows that compared with uncontrolled case, when the proposed method is used, the total travel time reduces by about 8.44%, and the average delay of road network reduces by about 62.97%; when the ALINEA approach is used, the total travel time reduces by about 2.85%, and the average delay of road network reduces by about 21.20%; when the linked-control approach is used, the total travel time reduces by about 6.00%, and the average delay of road network reduces by about 56.17%; when the proposed method is used, the traffic flow in mainline confluence area during congestion increases by about 540 veh？h-1, and the queue length of each ramp is more balanced. Obviously, the proposed method has good control result. 3 tabs, 12 figs, 25 refs