Research Of Traffic Condition For Setting Intermittent Bus Approach

Intermittent bus approach is a new type of bus priority at intersections.The theory of IBA is to give bus priority when a bus arrives at IBA and vehicles can have the right to occupy the IBA when the bus departs the IBA.In this way,the delay of vehicles can be improved while the buses get the priority at the same time.The utilization ratio of the approach resources is improved after setting the IBA.This paper analyzed the delay of vehicles and buses after setting IBA at an intersection.The traffic condition of setting IBA at intersections can be obtained on the base of analysis.The conclusions provide a theoretical basis to improve the attractiveness of public transport.The specific contents of this paper are as follows:Firstly,the paper analyzed the IBA control system and put forward some measures to optimize the IBA system.Queues of cars are accumulated and discharged following the changes of the signals at the intersection.Regarding the vehicles as a whole and using the shock wave theory,the open time formula of IBA and improved IBA control system can be obtained.The vehicles change lanes asymmetrically and buses can be only run on the IBA.The facilities and hardware equipments selection principle of IBA control system are summed up on the basis of the theory.Secondly,the theoretical analysis of the vehicles and bus delay after setting IBA is given.By using the delay model,this paper discussed the periodic delay of social vehicles in the process of opening IBA and closing IBA,and then obtained the formula for calculating the vehicle delay under different traffic saturations.According to the principle of IBA,the average delay formula of bus is obtained.Based on the analysis of the example,the changing trend of the delay of the social vehicles and buses before and after IBA is given.The changing trend of the delay with the signal period and the green signal ratio is analyzed,and the theoretical condition of the traffic saturation of the IBA with the minimum delay is(0.4,0.7).Thirdly,simulation analysis the delay of vehicles and buses before and after setting IBA is given.An improved model is established on the basis of the Nasch model and NS model,which can meet the vehicle driving rules before and after setting IBA in an intersection.Through the MATLAB simulation,we can get the traffic parameters such as the vehicle speed,the lane changing frequency of the vehicles on the approach.The relationship between the traffic parameters and the traffic saturation rate during different signals are plotted.The parameters of the simulation are processed,and the vehicle delay difference is calculated before and after the IBA,which is compared with the theoretical delay difference.Finally,the traffic conditions of IBA are analyzed.Combined with the simulation data at different signal cycle length and green signal ratio,trend of the total delay difference before and after setting IBA can be plotted.According to the evaluations of the improved IBA effect of the traffic parameter change rate,the paper concludes that the set of IBA reasonable traffic saturation conditions.