| In recent years,the urban express service has developed rapidly,and customers have become more and more aware of the timeliness of urban express products.With the continuous upgrading of new retail,more intra-city delivery demands will be generated in the future.Currently,the major express companies are actively seizing market opportunities and deploying intra-city express delivery.However,the distribution mode based on ground transportation has shown some disadvantages,such as poor timeliness,easy to be affected by urban road traffic and so on.The emerging underground logistics system provides a new way to solve such problems.In this paper,taking J Company’s urban express service as the research object,putting forward a new intra-city express delivery mode based on metro network,which is called ground terminal delivery and Metro transportation.Then the paper focuses on the location of the transfer center and the optimization of the delivery route.Firstly,based on the historical operation data of J Company,the paper analyzes the characteristics of customers’ geographical location,delivery time windows and delivery distance,and demonstrates the feasibility and necessity of Metro logistics distribution.Secondly,choose the location of the subway transfer center,and take the core station as the hub of the underground logistics system,which is responsible for the delivery service of express parcels in the area under its jurisdiction.First of all,the AP clustering algorithm is designed to divide the subway network by distance characteristics,and each subway station in the sub-region is regarded as a candidate transfer center,then combined with the actual logistics volume,the p-median model is used to determine the best transfer center in the sub-region.Thirdly,on the basis of determined subway transfer center,the paper analyzes the problem of package delivery routing optimization between two transfer centers.Taking the whole life cycle of express packages and considering the requirements of bilateral time windows of sending customers,subway trunk transportation,unilateral time windows of receiving customers and vehicle load constraints,a routing optimization model with the objective of minimizing the distribution cost is established,and genetic algorithm is designed to solve the problem.In the algorithm,the heuristic rules of time window sorting and load constraint are embedded to generate the initial solution,the improved crossover operator is designed,and the 2-opt algorithm is embedded to locally optimize the mutation process.Finally,an empirical analysis of the actual operating data of the Beijing subway network and J company is carried out,the subway network is divided into 14 sub-regions and 14 subway transfer centers are determined.Taking the stations from Zhongguancun to Huilongguan as an example,the relationship between the timeliness and distribution cost of express delivery is discussed,which provides a certain reference value for the operation managers of J Company. |
