Abstract

Models are presented for the optimal location of hubs in airline networks, which take into consideration the congestion effects. Hubs, which are typically the most congested airports, are modeled as M/D/c queuing systems. A formula is derived for the probability of a number of customers in the system, which is later used to propose a capacity constraint. This constraint limits the probability of more than b airplanes in queue, to be smaller than or equal to a given value. Due to the computational complexity of the formulation, the model is solved using a heuristic based on tabu search. Computational experience is presented together with an example using a data set available in the literature. In order to take advantage of economies of scale, most major airlines have selected some airports as transshipment points (hubs). As hubs become congested, the usual hub siting techniques fail in finding their best locations. We propose new methods for locating congested hubs and allocating runways to hub airports. _cr 2002 Elsevier Science Ltd. All rights reserved.