Models for fixed hub center location routing and hub network design

The design of hub-and-spoke networks is one of the most important problems in transportation and logistics management. One of the most essential features of such a network is determining vehicle routes and the locations of hubs. Generally, these two main problems are considered separately in the literature. In this thesis, assuming the locations of the hubs are pre-determined and each non-hub city is served from a hub; firstly, we relax one of the main assumptions in the hub location literature that one vehicle has to operate between each demand center and hub. We propose into the literature Fixed HUB Center Location Routing Problem's mixed integer mathematical programming formulation. The aim of this problem is to allocate demand centers to the hubs and determine the routes of vehicles for each hub such that the maximum travel distance between all origin-destination pairs is minimized. The applicability of this model is tested on some problem instances on Turkey dataset. Many articles in the hub location problem literature assume that the hub network design is complete. However, it has been observed that a complete hub network design is not required in most of the real life examples. For this reason; secondly in this thesis, we relax the complete hub network assumption in the fixed hub center and routing problem and we focus on designing the hub networks that are incomplete. In this thesis, assuming the locations of the hubs are pre-determined and each non-hub city is served from a hub; as far as our knowledge it is the first time we propose into the literature "Fixed Hub Center Location Routing Problem; and Incomplete Hub Network Design Problem" mixed integer mathematical programming formulation. The applicability of the suggested mathematical model is tested on some problem instances on Turkey dataset.