The Station Selection And Route Optimization Of Urban Distribution Network Based On Subway

Frequent and time-efficient logistics distribution service is an important part of modern city operations.However,traffic congestion has steadily worsened due to the growth of passenger volume,the increase of freight demand,and the shortage of road resources,making punctual delivery ever more challenging.Many cities have adopted restrictions on freight vehicles to alleviate traffic congestion,which has further reduced delivery timeliness.Subway transportation has begun to take shape and has a large,underutilized capacity.Therefore,it is necessary to explore the urban distribution network system based on subway.The network system has five key problems that need to be solved urgently.First,how to choose the transshipment node connecting the subway network and the road network? Second,how to assign goods to the transshipment nodes reasonably? Third,how to assign the goods to the trains reasonably? Fourth,how to choose the subway network route? Fifth,how to optimize the delivery route? The above-mentioned problems are interdependent and affect each other.Therefore,it is necessary to optimize them in a combined framework.Based on the discussion and summary of the subway-based urban distribution network,the paper studies three combinatorial optimization problems.First,the thesis analyzes the basic forms of the existing urban distribution network and the subway-based urban distribution network.The feasibility of using subway in urban distribution is summarized,and the various distribution stages in the subwaybased urban distribution network are explained.The freight transport modes of subway are proposed in addition to serving passengers.The transportation capacity is further estimated,and freight transport modes under three different needs are selected.The potential carbon emission reductions are estimated,and the key enabling technologies for the combined distribution mode are analyzed.Second,the combination problem of the selection of transshipment nodes between subway networks and road transit networks,the assignment of customer demands,and the route selection between stations in the subway network is studied.It is assumed that the goods will be directly transported to customers after leaving the subway network.First,a transshipment nodes selection model without station storage capacity is constructed.Transshipment node selection and customer allocation are optimized after defining the route selection criteria between stations in the subway network.Then,a transshipment nodes selection model with station storage capacity and train capacity constraints is constructed.The corresponding optimization algorithms are designed respectively,and the solutions are provided using the transportation of goods on the subway network of Chengdu as an example.Third,the thesis studies the assignment of customer demands and the arrangement of the service sequence of delivery vehicles on a single subway line with multiple stations.The optimization problem considers a single subway line and takes into account the train schedule.Two sub-problems are studied under the same background.In the first problem,a route optimization model with customers' time windows is constructed.In the second problem,limits of station temporary storage capacity and train capacity constraints are considered.A route optimization model with storage capacity at the transfer point is constructed.The optimization algorithms are designed respectively,and the solutions are provided using the transportation of goods on Chengdu Metro Line 3 as an example.Lastly,the thesis focuses on the selection of transshipment nodes between the subway network and the road transportation network,the assignment of customer demands,and the arrangement of delivery vehicles to serve customers after leaving the stations.A selection and route optimization model is constructed.The corresponding optimization algorithm is designed,and the solution is provided using the transportation of goods on the subway network of Chengdu as an example.In sum,to extend the usage of subways in urban distribution,the thesis has studied several combined optimization problems,including transshipment node selection,customer assignment,subway route selection,and delivery vehicle routing,in a subway-based urban distribution network system.Network system optimization theory provides ideas and methods for problem setting and solution algorithm design.The actual problems are mathematically abstracted with appropriate parameters,variables,and expressions to be formulated as optimization models,and the corresponding solution algorithms are designed.They provide auxiliary decision support for distribution enterprises,which has certain practical significance in real-world applications.Finally,the thesis highlights several directions of future research.First,the selection and assignment of transshipment nodes could consider the time dimension.Second,the assignment and routing optimization could be expanded to multiple subway lines.Third,the time-dependent location-routing problem combined with subway route selection in a subway-based urban distribution network is a theoretical problem worthy of further study.In addition,innovation in solution methods and validation using more practical examples will also benefit future research.