Research On Line-haul Network Design Of Road Express

For the past few years due to the rocketing development and intense competition in road express industry, how to build reasonable transport network, optimize vehicle routes and reduce operation cost have drawn more and more attention of road express enterprises.Hub-and-spoke transport network can effectively increase utilization rate of logistics resources and reduce logistics cost which is fairly suited for express freight especially for less-than-truck load (LTL). In hub-and-spoke network, goods need to be transferred at hubs before arriving in destination. During this process, the imbalance of vehicles and instability of departure terminals are common problems and there are few discussions on them. On the other hand, there is consolidation among terminals in the LTL mode, so the hub location and vehicle routing are hard problems in research area.This paper carries out researches on model and algorithms to solve the problems above and designs a reasonable hub-and-spoke network with stopovers which can reduce logistics cost. First, cost factors influencing network design are extracted and evaluating indicators of hub location such as rankings of freight volume and radiation limits of terminals are come up with according to freight flow and operation cost analysis. The improved AHP (Analytic Hierarchy Process) is used to choose candidate hubs. Secondly, aiming at the feature of "collecting first delivering later", the transport planning is divided into two parts and both of them are carried on with every candidate hub. The amount and location of departure terminals and vehicle routes are determined in the collecting planning and the delivery planning is solved based on the previous stage. OVRP (Open Vehicle Routing Problem) models with time constraint and capacity constraint are built under the condition of balanced vehicles and steady departure terminals and GA (Genetic Algorithm) is designed to solve the models. The validity of the algorithm is proved by simulation tests.This paper builds a hub-and-spoke transport network through a case study. First, freight data of the enterprise is investigated and the changing pattern of freight volume is analyzed to obtain the order of it; secondly, using electronic map software and minimal path program to calculate minimal distance among all terminals; finally, an aggregation of hubs and transport planning models are solved based on monthly mean freight volume and minimal distance matrix. A part of vehicles are adjusted through comprehensive analysis of results and the location of hub and vehicle routes plan are obtained by comparing total cost. From the result of transport network design, it can be seen that new network can save transport resources by 7.14%, increase transport efficiency by 18.48%, reduce operation cost by 12.85% in comparison with original network of enterprise. The application value of the network design plan and practicability of the models presented are validated through this case study.