Multimodal Transportation Planning For Multicommodity Flow Problem

Multimodal transportation refers to a combination using at least two modes of transportation to transport good or service such as truck,air,railway or water.Multimodal transportation has become increasingly important and dominating in the multicommodity flow problem.Due to the advantage of truck transportation in that it can provide door to door service,we always see the truck transportation as a component in the combination of modes for multimodal freight transportation like rail and truck transportation(piggyback),sea and truck transportation(Fishback),or air and truck transportation(birdy back).The Primary focus of our research has to presented a methodology for a more efficient way of freight transportation planning through the use of a multimodal network.Due to the necessity of using truck transportation as a component in the network of multimodal transportation,the complexity of planning the multimodal transportation network emerges because of the difference of truck transportation from other modes of transportation.Water,rail,and air transportation services are often scheduled services,which mean these three modes can serve only on fixed schedule of departure and arrival times;on the other hand,truck transportation is more flexible in the aspect of time in that it can provide flexible time service.To plan the multimodal freight transportation network in an efficient manner,the planner has to synchronize the flexible-time service of truck transportation with the scheduled-time service of rail transportation.This paper considers the network of a company that operates express delivery service by transporting customers' demands through the multimodal transportation network of rail and truck transportation.The authors formulate the problem as a multicommodity flow problem on a representative network.The objective of this optimization model is to minimize the total transportation cost and the travel time of each commodity,which is defined by its origin-destination(OD)pair.To this end,we model the problem as a mixed integer linear program(MILP),which determines the routing of customer orders,the transportation mode to use on each route segment,and the corresponding departure and arrival time of the selected mode.