A branch-and-cut algorithm for the Time Window Assignment Vehicle Routing Problem

This paper presents a branch-and-cut algorithm for the Time Window Assignment Vehicle Routing Problem (TWAVRP), the problem of assigning time windows for delivery before demand volume becomes known. A novel set of valid inequalities, the precedence inequalities, is introduced and multiple separation heuristics are presented. In our numerical experiments the branch-and-cut algorithm is 3.8 times faster when separating precedence inequalities. Furthermore, in our experiments, the branch-and-cut algorithm is 193.9 times faster than the best known algorithm in the literature. Finally, using our algorithm, instances of the TWAVRP are solved which are larger than the small scale instances previously presented in the literature

Time Window Assignment in Distribution Networks

In delivery networks, companies assign time windows to customers, informing them between which times they may expect service. Unfortunately, these time windows are often too wide to be informative, for example from 9am to 5pm. Another problem is that time windows may not be met due to unforeseen delays. In this thesis, we study assigning time windows in distribution networks to improve customer satisfaction. More and more companies realize that the satisfaction of their customers is import

Resource-robust valid inequalities for set covering and set partitioning models

For a variety of routing and scheduling problems in aviation, shipping, rail, and road transportation, the state-of-the-art solution approach is to model the prob- lem as a set coverin

Dynamic Time Window Adjustment

To improve customer satisfaction in a delivery network with uncertain travel times, we propose to communicate time window adjustments to the customers throughout the day. We refer to these updates as dynamic time window adjustments. Dynamic time window adjustments are often used in practice, but have not yet been considered in the scientific literature. We provide a general model and we present the Dynamic Time Window Adjustment Problem (DTWAP). The DTWAP is the problem of optimizing the dynamic time window adjustments to maximize the expected customer satisfaction for a given route. Instead of solving the DTWAP in a specific setting, we derive general properties and we present three different solution methods. We also introduce the simple DTWAP, which is a special case that we analyze in more detail. The use of our results is demonstrated with an illustrative example concerning attended home delivery

A branch-and-cut algorithm for the Time Window Assignment Vehicle Routing Problem

This paper presents a branch-and-cut algorithm for the Time Window Assignment Vehicle Routing Problem (TWAVRP), the problem of assigning time windows for delivery before demand volume becomes known. A novel set of valid inequalities, the precedence inequalities, is introduced and multiple separation heuristics are presented. In our numerical experiments the branch-and-cut algorithm is 3.8 times faster when separating precedence inequalities. Furthermore, in our experiments, the branch-and-cut algorithm is 193.9 times faster than the best known algorithm in the literature. Finally, using our algorithm, instances of the TWAVRP are solved which are larger than the instances previously presented in the literature