Capacitated hub location problems with waiting time at hubs

A new subject in the scope of capacitated hub location problems is presented. In most of postal networks or data and airline networks, hubs are special facilities that act as consolidation, sorting and distribution centers of flow. Since the models dealing with these problems focus on economic benefits with respect to costs of routing and opening hubs, there may be congestion of passing flow at some hubs. We concentrate on postal networks and consider every hub as M/M/1 queueing system to restrict mean time spent by unit of flow at hubs. Models including capacity constraints are derived for both single and multiple allocation types, and the CSAHLP model is tested on a data set available in the literature by GAMS to analyze the computational results.