Study On Location Selection Of City Underground Logistics System Node

In recent years,urban traffic congestion has gradually become a common problem faced by the world’s major cities.To effectively solve the increasingly serious traffic congestion problem of large city,Japan,the Holland, the United States and other countries have turned to underground,hoping to diverted most of the goods on the ground to underground to ease the traffic pressure on the ground and reduce the environment pollution through the establishment of urban underground logistics system.A complete underground logistics network is consisted of logistics codes,logistics lines,clients and special vehicles.Logistics node is the key of the whole underground logistics network,its position determines the structure and scale of the entire logistics network,which directly affects the construction cost and customer service levels of the entire logistics system.The main problem of this study is how to realize the ULS node location optimization based on actual situation of the city through the combination of qualitative and quantitative methods in the logistics system planning period.This paper first introduces the development of underground logistics system at home and abroad and relevant concepts of underground logistics system.The city underground logistics system model is explored,the design scheme of underground logistics transportation channel and carrier is analyzed and the operating mechanism of underground logistics node is discussed.Secondly,starting from the characteristics of logistics node,the bi-level programming model which both considers the interests of logistics planning department and customers is created based on the analysis of several location models.From the perspective of decision makers,the upper programming hopes to obtain the generalized minimal logistics costs by considering the relationship among logistics node layout and delivery costs,service costs,fixed costs and variable costs.The lower programming describes the choice behavior of customers and its goal is to make each customer use minimum cost.Bi-level programming problem is a NP-hard problem and this paper uses genetic algorithm to solve the model in MATLAB software.Finally,the logistics planning of Chongqing is taken as an example in the thesis.The node conception map of underground logistics system in Chongqing is drew by qualitative analysis based on analyzing the demand of Chongqing underground space development.Then the simulation data is put into the model with geneticalgorithms solver and more scientific and reasonable nodes are selected from the alternatives nodes.The bi-level programming model is proved scientific and effective in solving logistics node location problem and reference scheme can be provided in the application of underground logistics system in actual life.