Optimization of mail collection networks

Some providers of postal or parcel services promise high levels of service to their customers, e.g., next day delivery, resulting in tight lead times. To meet these high service levels, complex logistics networks need to be planned and operated. Such networks are typically divided into transportation of letters or parcels from customer locations to a local sorting terminal (collection), inter-terminal transportation, and transportation from a terminal to customer locations (delivery). Within postal logistics networks the interaction of processing at and transportation between different kinds of facilities plays a vital role. Normally, collection and initial sorting, as well as inter-terminal transportation and final sorting need to be finished before certain cut-off times. Thus, guaranteeing the subsequent transportation to start on time. The talk presents various optimization problems within the part of a postal logistics network where collection takes place. Then, two of those problems are presented in more detail. First, the allocation of pickup locations to sorting terminals and, second, the optimization of collection tours. Both problems not only consider service time windows at customer locations and at terminals but also complex sorting capacities at the sorting terminals. For both problems appropriate mathematical models and solution methods will be discussed. Also generic and practical applications are presented.