A time–cost optimization of the national postal distribution network

The postal distribution network in the Czech Republic consists actually of 69 local transit centres (according to the administrative division of the Czech Republic). Each of them operates the post offices in the given region. Some of the important local transit centres can be selected as sorting centres – transhipment points for postal consignments. The aim of this paper is to present a bicriterial optimization model for the selection of the subset of transhipment points from the set of transit centres and choosing their appropriate equipment, such as sorting machines. Another important output of the model is the assignment of the transit centres to the sorting centres. There are two basic optimization criteria defined in this model: minimization of the sum of investment and operational costs connected with building and operating of the sorting centres and the maximization of the percentage of postal consignments delivered to the appropriate post office in the desired time (next day). The proposed model contains several thousands of zero–one variables and constraints. The model has been verified, and the results accepted.