A Scheduling Approach for a Single allocation Hub Location Problem under Congestion and Uncertain Environment

Because of the fundamental effect of hubs in mass traffic movement and preventing the reduction in network throughput, it is necessary to consider the congestion effects. Congestion occurs at hubs in the network, where the total incoming traffic exceeds the allowed capacity. To control the congestion, we consider scheduling to find the optimal schedule for entered flows from other nodes to each hub in addition to find the best location of hubs and allocation of non-hub nodes to located hubs. Flows from different nodes are not allowed to enter each hub simultaneously. The incoming flows from other nodes must be entered in different time periods and each flow must be processed continuously in hubs. The aim of scheduling is to plan and arrange entered flows from other nodes to each hub in an orderly sequence of operations in order to minimize tardiness penalty and waiting costs. In this paper, a single allocation hub scheduling problem under uncertain environment is modeled. The developed model seeks to minimize the transportation, hub installation, tardiness penalty and waiting costs. The model is tested by GAMS to find the exact solutions of small instances. Finally, conclusions are provided.