Vehicle Routing Problem With Many Time Windows In A Hub And Spoke Network

Tractor and semitrailer transportation has become an important strategic development orientation of road freight industry in China with its advantages of high efficiency,low cost and low environmental pollution.However,the time efficiency of tractor and semitrailer has an antinomy relationship.It's more and more important to improve the time efficiency of semitrailer under the condition that the ratio of tractor and semitrailer is lower in China.Thus,based on the characteristics of provincial trunk line transportation in express delivery industry this paper studied the dispatching problem of truck and tractor and semitrailer transportation,which is in line with the development direction of logistics industry transformation and upgrading in China and has strong foresight in theory and considerable economic value in practice.In this paper,firstly,the development status of classical vehicle scheduling and tractor and semitrailer scheduling and the organization mode of tractor and semitrailer transportation are systematically combed and the reasonableness of selecting the saving algorithm based on heuristic vehicle scheduling rules is expounded combined with network structure of trunk line transportation in China and the characteristic attributes of research problems.Then,taking the common truck as the research object,considering the limitation of vehicle capacity and the many time windows of nodes,the truck dispatching model under the hub-and-spoke network is established and solved.Following,change the transportation tool under the above research background,based on the network characteristic put forward the "multi line one point,take towing in turn" organization mode,model and solve tractor and semitrailer cooperative scheduling problem.Finally,the validity of the model and algorithm is verified by the example analysis of Guangdong postal district of China Post,and the key factors affecting the vehicle and tractor and semitrailer cooperative scheduling effect under the hub-and-spoke network are further clarified.Comparing and analyzing the dispatching results of the truck and the tractor and semitrailer transportation,the superiority of the tractor and semitrailer transportation is highlighted,which provides the theoretical basis and the decision reference for the road freight enterprise to carry out the tractor and semitrailer transportation.It is the innovation of this paper to realize the cooperative scheduling of tractor and semitrailer considering the effect of the effective utilization ratio of semitrailer on the overall efficiency of transportation.Meanwhile,based on the actual situation of provincial trunk line transportation,the hub-and-spoke network which is easy to form scale effect is selected.The vehicle scheduling in this structure shows that the nodes are not exclusive,loading and unloading mixing,many time windows,and so on,which is quite different from the characteristics of the vehicle scheduling under the fully connected network structure.In general,this paper realizes the change of transportation tools from the traditional truck to tractor and semitrailer,and closely combines the development direction of deepening the reform of the logistics industry combined with the present situation of highway transportation in China,which has a strong practical value and broad development prospects.