The Hierarchical Cycle Hub Location Problem

This paper presents the hierarchical cycle hub location problem. This new problem is an extension of the cycle hub location problem (CHLP). It is a three-layered hub network problem where the top level consists of a cycle network connecting the so-called central hubs and the second and third level are unions of star networks connecting the intermediate hubs to central hubs and the demand centers to intermediate and central hubs, respectively. The problem is to decide on the locations of a predetermined number of intermediate and central hubs and the connections in order to minimize the total routing cost in the resulting network. We also propose two mixed integer linear programming formulations for the problem. The behavior of the proposed models, in terms of solution time, is evaluated on the basis of an extensive computational study on Turkish pastal network dataset. The results achieved by CPLEX and Xpress solvers, based on the proposed MILP formulation, are compared to each other. We have also reduced the time to solve the problem by changing the parameters of the solver