Intégration de l'expérience des livreurs aux problèmes de tournées de véhicules

Ce mémoire introduit une nouvelle variante aux problèmes de tournée de véhicules visant à prendre en considération la connaissance et l'expérience des livreurs dans le processus d'affectation aux clients. Ce nouveau type de tournée de véhicules basés sur l'expérience (EB-VRP) est motivé par le gain potentiel que pourrait apporter la familiarité des livreurs avec leur zone de travail, non seulement en termes de coûts de transports, mais également de satisfaction des livreurs. Cette approche pourrait également avoir pour corollaire une consommation ré- duite de carburant ainsi qu'une affectation non biaisée des livreurs aux clients. Pour traiter ce nouveau problème, une méthode de représentation de la connaissance construite à partir d'un historique de livraison est proposée. La résolution est ensuite effectuée par une approche bi-objectif combinée à une heuristique à grand voisinage. Des résultats numériques issus de données réelles viennent corroborer la pertinence de cette méthodologie.This thesis introduces a new type of vehicle routing problem aiming to take into account the knowledge and experience for the driver-customer affectation process. This new experiencebased problem (EB-VRP) is motivated by the potential gain that could result from the ftting between drivers and their working areas in, in terms of global transportation costs and driver's satisfaction. This approach could also lead to a lower fuel consumption and an unbiased driver-customer affectation. A new methodology had been introduced to address this new problem, featuring a way to model the driver's knowledge based on a delivery's history. A bi-objective approach combines with a large-scale neighborhood heuristic had been used as a solving method. Numerical results from real data support the relevance of our methodolog

Vehicle sharing and workforce scheduling to perform service tasks at customer sites

Most of the research done in the Vehicle Routing Problem (VRP) assumes that each driver is assigned to one and only one vehicle. However, in recent years, research in the VRP has increased its scope to further accommodate more restrictions and real-life features. In this line, vehicle sharing has grown in importance inside large companies with the aim of reducing vehicle emissions. The aim of this thesis is to study different situations where sharing vehicles brings an improvement. Our main study focuses on developing a framework that is capable of assigning different workers to a common vehicle, allowing them to share their journey. We introduce a mathematical programming model that combines the vehicle routing and the scheduling problem with time constraints that allows workers to share vehicles to perform their activities. To deal with bigger instances of the problem an algorithm capable of solving large scenarios needs to be implemented. A multi-phase algorithm is introduced, Phase 1 allows us to solve the non-sharing scheduling/routing problem whose aim is to find the best schedule for workers. Phase 2 will merge the allocated workers into common vehicles when possible, while Phase 3 is the improvement procedure of the algorithm. The algorithm is tested in three different settings; using workers as drivers, hiring dedicated drivers, and allowing workers to walk between jobs when possible. Results show that sharing vehicles is practicable under specific conditions, and it is able to reduce both the number of vehicles and the total distance, without affecting the performance of workers schedule

Territory-Based Vehicle Routing in the Presence of Time-Window Constraints

Territory-based routing approaches (TBRAs) are commonly used to achieve high service consistency, e.g., in the small package shipping industry, but their drawback is a decline in routing flexibility. Consequently, a high percentage of time-definite deliveries, as common in the small package shipping sector, should have a significant negative effect on the solution quality of TBRAs. To the best of our knowledge, no study exists on the magnitude of this effect and the factors that influence it. Therefore, we develop a two-phase TBRA and use it (i) to investigate the design requirements of a TBRA for successfully handling time windows, and (ii) to study the influence of time window constraints on the performance of such an approach. We find that the consideration of geographical aspects in the districting is paramount for generating high-quality territories, whereas explicitly incorporating time window characteristics and historical demand data does not lead to a perceptible improvement of the solution quality. Moreover, the efficiency and feasibility forfeits of our TBRA in comparison to daily route reoptimization (RR) are larger if time windows are present. However, significantly higher consistency improvements compared to RR are achieved for time-constrained problems. This is due to the fact that RR solutions to time-definite problems exhibit lower consistency and thus a higher potential for improvement by using a TBRA, which constitutes an important insight for practitioners

Recent Mathematical Approaches to Service Territory Design

Many companies and institutions operate a field service workforce to provide services at their customers\u27 sites. Examples include the sales force of consumer goods manufacturers, the field service technicians of engineering companies, and the nurses of home-health care providers. To obtain clearly defined areas of responsibility, the geographical region under study is in many cases subdivided into service territories, each of which is served by a single field worker or a team of field workers. The design of service territories is subject to various planning criteria. The most common ones are geographical compactness, contiguity, and balance in terms of workload or income potential, but there can be several additional criteria and requirements depending on the specific application. In this thesis, we deal with the development of mathematical models and methods for service territory design problems. Our focus is on planning requirements that are relevant for practice, but have received little attention in the existing literature on territory design so far. We address the question how these requirements can be incorporated into mathematical models and mathematical programming based solution methods. We first present requirements that restrict the feasible assignments of customers to field workers and provide components for their integration into mathematical models. We further consider the requirement that customers must be served multiple times during a given planning horizon. We introduce the resulting problem, which we call the multi-period service territory design problem (MPSTDP). It has not yet been studied in the literature. The emphasis is put on the scheduling task of the MPSTDP, which deals with the assignment of service visits to the days of the planning horizon. We formally define this task and devise a heuristic solution method. Our heuristic produces high-quality solutions and clearly outperforms the existing software product of our industry partner. Moreover, we present the first specially-tailored exact solution method for this task: a branch-and-price algorithm that incorporates specialized acceleration techniques, such as a fast pricing heuristic and symmetry reduction techniques. Ultimately, we study the design of territories for parcel delivery companies. We address the tactical design of the territories and their daily adjustment in order to cope with demand fluctuations. The problem involves determining the number of territories and assigning heterogeneous resources to the territories, a combination not yet addressed in literature. We propose different models as well as a heuristic solution approach, and we perform an extensive case study on real-world problem data