Optimization methods for multi-echelon vehicle routing problems with intermediate transshipment points

Abstract

This thesis studies multi-echelon vehicle routing problems with intermediate transshipment points and practical constraints. Multi-echelon vehicle routing problems constitute a core class of problems in the transportation and operations research literature, with numerous exciting variants and applications, especially within the freight distribution and logistics domain. The most representative examples of this class of problems are found in urban freight distribution (Crainic, 2008), press distribution (Gonzalez-Feliu and Morana, 2011), parcel and postal distribution (Gracin and Stipetić, 2009) as well as intermodal transport (Lowe, 2005). Transportation-related costs make up about 20% of the cost of manufacturing (Chopra and Meindl, 2009) as well as 30% of an item’s price (Musa et al., 2010). Therefore, the reduction of transportation costs coupled with the increase of customer service, is of major importance for logistics companies and transportation service providers. Potential savings up to 20% of the transportation costs, might be achieved by the use of computerized procedures for planning distribution processes (Toth and Vigo, 2002). For this purpose, academic researchers as well as private companies have been motivated to develop innovative optimization models and solution algorithms in order to improve the efficiency of multi-echelon distribution networks, in pursuit of cost savings and increase of customer service. The family of pickup and delivery problems covers a broad range of optimization problems within the multi-echelon distribution context. This thesis focuses on problems where goods have to be transferred from several pickup points to several delivery points with or without intermediate transshipment points. […]

Η διδακτορική αυτή διατριβή πραγματεύεται την ανάπτυξη μεθόδων βελτιστοποίησης για την επίλυση πολύπλοκων Προβλημάτων Δρομολόγησης Στόλου Οχημάτων Πολλαπλών Επίπεδων με Διαμετακομιστικούς Κόμβους. Ο στόχος της έρευνας είναι αφενός να μελετήσει σύνθετα ρεαλιστικά προβλήματα με διάφορους επιχειρησιακούς περιορισμούς, αφετέρου να αναπτύξει αποτελεσματικές μεθόδους βελτιστοποίησης για την επίλυση των προβλημάτων αυτών εντός ρεαλιστικών για πρακτικές εφαρμογές, υπολογιστικών χρόνων. Εξετάζονται επίσης διαφορετικές δομές δικτύων διανομής με διαμετακομιστικούς κόμβους και συγκρίνονται εναλλακτικές στρατηγικές διανομής για τη διακίνηση φορτίου. […]