At present,the city distribution mainly depends on ground transportation such as electrical bikes and small pickup trucks.The limitation of ground transportation is negatively affected by various factors like rush-hour congestion,vehicle restrictions and sleety weather.As a new way to solve these traditional traffic problems,the underground logistics has been successfully applied in the world.In this paper,the innovative use of the urban subway to design the city express delivery network has a great significance for the solution to the problems of large cities' distribution.Firstly,the sites of distribution center are determined,the main station of metro,which connecting ground and underground traffic system,has been selected to be the distribution center.By building the city's subway network structure,analyzing the network features,selecting the evaluation index by complex network theory,calculating the weight of each evaluation index by AHP method and evaluating the importance of each site by TOPSIS model,the pre-candidate distribution centers have been selected.Secondly,combined with the distribution characteristics of city's logistics flow and the site selection model of city distribution centers,the final distribution centers of city distribution are determined.Then,rely on the subway transportation to achieve the long distance trunk line delivery,an optimization for city express routines has also been made,while the collection and delivery will still be traditional ground ways.Considering the time window and the frequency of line haul transportation,an VRPTW model has been built to minimize the total delivery time and solve it by genetic algorithm.Finally,an empirical study of Shanghai has been carried out to scientifically design the distribution center of city distribution and get the shortest delivery routes. |