| With the continuous improvement of urbanization rate and steady progress of population and industrial urbanization,the travel demand of residents between urban areas and suburbs is increasingly close.Under the changing trend of urbanization spatial pattern,many cities vigorously develop rail transit,BRT and other high-capacity public transport modes,which effectively alleviate traffic problems such as traffic and parking difficulty,meanwhile promote the sustainable development of urban transportation.However,the main transit in suburban areas is to be perfect,and there are defects such as scattered station settings and sparse line network density.The "last kilometer" problem has brought serious troubles to residents’ travel.The flex-route feeder transit system aims to realize the transfer connection with the main transit,provide efficient and flexible door-to-door connection service for passengers,and at the same time enrich the urban bus structure and improve the service level of public transport.This paper takes FFTS as the research object to study its operation optimization.Specific research contents are as follows:(1)Analyzed the framework and definition of FFTS,proposed L and Z two modes,determined two modes operation characteristics and operation optimization key influence factors,including passenger travel characteristics,fleet size and time window constraints.(2)Established the operation optimization model of FFTS,including the operation mode optimization model and the routing and schedule collaborative optimization model.Operation mode optimization model considering the difference between two operation modes,with the goal to minimize the total cost of enterprise and passenger,combined with vehicle and passenger time window constraints,vehicle routing rationality,et al.Comparing the utility function of two modes,get the optimal operation mode;On this basis,the co-optimization model of routing and schedule is built from the perspective of passengers,and passenger walking strategy is introduced to the objective,also increasing passenger tolerable maximum time and distance constraints,so as to optimize routing and schedule of vehicles.(3)Designed the operation optimization algorithm for FFTS,which also includes operation mode optimization algorithm,routing and schedule collaborative optimization algorithm.The operation mode optimization algorithm is divided into two parts: passenger demand allocation and vehicle routing planning.The routing and schedule collaborative optimization algorithm overcomes the local optimal defect,takes the result solved by the insertion method as the initial solution,adopts 2-opt algorithm for neighborhood design,and combines with tabu search algorithm to calculate the global optimal solution of vehicle routing.(4)Simulation analysis for FFTS operation mode,routing and schedules collaborative optimization model,the result shows,L mode is more suitable for a longer service area,with the adaptation length ranging from 9 to 12 kilometers.Z mode is more suitable for shorter service areas,with the adaptation length ranging from 3 to 6 kilometers.In 10 ～ 100 passengers / hour,the system total cost of L mode is better,the average passenger walking time,transfer waiting time and in-car time are stable at about 6 minutes,4 minutes and 7minutes respectively,and the vehicle routing and schedule are obtained.To sum up,based on the urbanization process and the development status of public transit in China,this paper studies the operation optimization of FFTS,provides practical theoretical guidance for solving the "last kilometer" problem,and helps promote the diversification and personalized development of public transit. |
