| The unbalanced regional production and consumption have caused the asymmetric volume and direction of cargos in the field of international container shipping.As a result,a large number of empty containers are piled up in the ports of importing countries,while the ports of exporting countries are facing the problem of shortage of empty containers.In order to save cost,liner shipping companies generally use the surplus capacity of laden container transportation to complete empty container repositioning in practice.Under the above background,the optimization of laden/empty container transportation plan has become a scientific issue of common concern to the practical departments of liner shipping companies and scholars in the shipping field.At the same time,from the beginning of circulation and use,containers will face the situation of increasing maintenance cost and decreasing residual value with the increase of service time,and container maintenance cost and scrapping residual value vary greatly in different regions.It is estimated that about 2 million TEU containers are scrapped annually in the global shipping market.The available value of such a large number of scrapped containers should not be neglected by liner shipping companies.When optimizing the liner shipping laden/empty container transportation plan,the advantages of considering the sites for scrapping worn containers are as follows:First,if liner shipping companies choose to scrap worn containers at ports of importing countries where empty containers are piled up,the number of empty containers repositioned from empty container surplus areas to empty container deficit areas can be reduced accordingly;Second,scrapping worn containers in advance at ports where the price of purchasing worn containers is relatively high will help to save the cost of container maintenance and better realize the residual value of containers.Based on this,after the summary of the related theoretical basis and the introduction of concept of containers’ lifecycle,from the perspective of a liner shipping company,this paper puts forward the idea of dividing the containers into different stages of lifecycle by the time they have been put into use and innovatively adding some decision-making factors,such as the sites where worn containers are scrapped when optimizing laden/empty container transportation plan.Based on the given combined hub-and-spoke shipping routes and laden container OD,a mixed integer linear programming model is built to optimize the ship fleet deployment of liner shipping routes,the transportation routes for the laden containers and the empty containers,the sites for putting the new containers into use,the sites for scrapping the worn containers and which lifecycle stage of containers to choose for specific transportation plans.The area which consists of China,Japan and South Korea,Southeast Asia,Europe,and the United States is used to do the case study.The calculation results can be summarized as follows:The new containers need to be put into use in areas which are at shortage of empty containers,cargos from trade surplus areas to trade deficit areas may preferentially be transported in worn containers,and this part of worn containers can be scrapped on site after arriving at the destination.In this way,the liner shipping company can control volume of empty container repositioning,save the container maintenance cost and better realize the residual value of containers.The final conclusion of this paper is that it is necessary to consider the sites for scrapping worn containers and implement specific transportation plans according to the characteristics of different stages of container lifecycle when optimizing liner shipping laden/empty container transportation plan and that the model can optimize the whole process of containers from birth to market use and then to market withdrawal,and reduce the operation cost of liner shipping companies. |
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