Optimization And Synergy Of Rail Trunk Line And Bus Feeder System Considering Space Heterogeneity

With the vigorous development of China’s urban public transportation and the guidance of the "public transport priority" policy,the urban public transportation system is being further improved,the overall operating capacity is constantly improving,and the changes in the structure of urban public transportation passenger transport are gradually becoming apparent.In large and medium-sized cities,rail transit has gradually become the mode of transportation with the largest proportion of passenger flow,and conventional buses have become an important mode of assisting transportation in the distribution of rail passenger flow.In order to improve the quality of public transportation services,ensure the accessibility of public transportation,and provide convenient travel for passengers at the same time,regular bus transportation and rail transportation are usually combined.In the existing studies,the joint transportation of rail transit and conventional buses is mostly the connection of lines and stations,and there is still a gap in the research on the implementation of the departure time synergy.Based on the research of the bus corridor consisting of the main rail and the feeder line of the bus,this paper optimizes the layout of the main rail station by constructing the objective function with the lowest total cost of the system,and simultaneously controls the departure time of the main rail transit and feeder bus.Firstly,select the transit corridor consisting of trunk rail and feeder buses as the research basis,and build the objective function of minimizing the total cost of the system including passenger walking costs and operating unit expenditures.The decision variables are the density of the main rail station,the interval between the main rail and feeder buses.Determine first order derivative and iteration to stationary for multiple times to get the optimal rail transit station density function.Through the integral endpoint method,the optimal rail transit station density function is integrated to obtain the specific layout position of the rail transit station.Afterwards,we define the formula of the time interval synergy,and the time interval synergy multiple is regarded as a new continuous decision variable,and the analytical formula of the optimal time interval synergy multiple is obtained through the first-order differential derivation.The position coordinate of each feeder bus is brought into the analytical formula of the optimal multiples of the synergy multiples,and the coordinate multiples corresponding to each feeder bus are obtained.The total cost of the system is discretized,and an evolutionary algorithm based on orthogonal experiments is used to find all the multiples of the time interval synergy which minimize the total cost of the system.Finally,a traffic simulation test was performed on Shenzhen Metro Line 11 to set the time interval and the range of connection nodes.At the same time,the vehicle input and vehicle running time,vehicle delay,fuel consumption,emissions and other evaluation parameters were set.Then simulating the test sections before and after the time coordination.Through the construction of the model and the simulation operation of the example,it is proved that the time-coordinated optimization scheme proposed in this paper has many benefits for the operation of the bus corridor under the heterogeneous many-toone travel demand characteristics: the total cost of the system is effectively reduced,and the time of vehicles occupy on line network is reduced,transportation efficiency is improved,and the occurrence of bus congestion is reduced;passenger travel time is reduced,and bus service quality is improved;operating unit costs are saved,and transportation resources are efficiently and intensive;it will be benefit to energy saving and environmental protection and building an environmentally friendly city.