Introduction

Abstract

The overwhelming majority of research dealing with scheduling or vehicle routing problems is devoted to classical problems like the capacitated vehicle routing problem with time windows, the pickup and delivery problem, or the resource-constrained project scheduling problem. In practical applications, however, there generally exist more complex requirements that do not fit these basic problems. Moreover, many real-world problems arising in multi-site project management or supply chain planning involve interdependent scheduling and routing decisions. If these requirements are not considered in the planning process, the resulting schedules may require considerable rework before being implemented or may even be infeasible for practical use. On the other hand, adapting a scheduling or routing procedure designed for a basic problem to a more general problem is often very expensive and may lead to inefficient algorithms. Hence, most of the solution approaches presented in the literature cannot be easily adapted to complex real-life instances combining several non-standard problem features. However, separating the scheduling and the routing part into disjoint models and solving them sequentially, as it is done within a hierarchical planning approach, may lead to considerable performance losses. Only few papers address more general concepts that allow for covering diverse practical requirements. By developing the resource transfer model and a corresponding solution approach we aim at reducing the gap between academic problems and the requirements of scheduling and vehicle routing professionals.