Research On Control Method Of Intermittent Bus Rapid Transit Lane Based On Cell Transmission Model

Urban road resources are increasingly scarce,and the bus lane system with independent right-of-way lanes often has low efficiency and the entire lane is idle.The intermittent bus lane system discussed in this thesis allows ordinary vehicles to use the bus lane when the bus lane is idle and without affecting the normal operation of the bus.The system can make full use of the idle capacity of the bus lanes to maximize the overall capacity of the road.Based on the macro-cell transmission model,this thesis takes into account the heterogeneity of buses and cars.The sequence vectors are introduced to record the order of vehicles on the bus lane.By combining the macro-simulation with the micro-simulation,the intermittent bus-only lane cell transmission model is developed.Due to the different speed limits of bus lanes and ordinary lanes,the intermittent bus lane cell transmission model has been further expanded from the aspects of cell distribution,flow transmission,delay calculation,etc.,to build a model for full-segment simulation considering different lane types.In addition to building a model for simulation,this thesis designs an optimization algorithm to solve an important control parameter in the model—the access ratio,which controls the number of ordinary vehicles entering the bus lane.In this thesis,the genetic algorithm is used to minimize the system delay as the objective function,and iterate the population to find the optimal individual.The prerequisite for intermittent bus lanes is that bus operation is not affected.In order to ensure this basic condition,this thesis improves the genetic algorithm.According to the idea of "survival of the fittest",in the stage of population selection and selection,individuals who do not meet the conditions are eliminated to obtain the control parameters that meet the requirements of the intermittent bus lane system.This thesis takes the elevated bus lane of Chengdu Second Ring Road as the test area.The basic section with single entrance and single exit and the extended section with double entrance and double exit are selected to construct simulation models to simulate the operation of vehicles in the intermittent bus lane system.According to the combination of different arterial road flows and ramp flows,the control parameters and optimization effects of the intermittent bus lane system under different traffic flow ranges are solved through an improved genetic algorithm.Furthermore,the impact of bus departure frequency and the bus stop time on the system performance is analyzed.The results show that when the sum of the main road and the on-ramp flow exceeds the road capacity,and the main road saturation is between 1 and 1.2,the admission control is implemented to allow vehicles to enter the bus lane such that the main road section can be restored to a smooth state and the overall vehicle delay on the road section can be greatly reduced.With the increase of traffic flow,when the main road saturation flow rate exceeds 1.2,the proportion of delay reduction is reduced to35%-55%.In the study of the expansion scenario,it is found that with the extension of the length of the road section and the increase in the number of entrances and exits within the optimal flow control range of the main road saturation between 1 and 1.2,and the traffic flow of each lane of the main road is below 1800pce/h,intermittent bus lanes can provide good optimization performance.Therefore,the expansion of the scene can effectively increase the optimal flow control range of intermittent bus lanes.