Two-Echelon Location-Routing and Vehicle Routing Problems in City Logistics: Definitions, Flow Models, and Solving Methods
Abstract
This chapter presents the main notions of two-echelon vehicle routing (2E-VRP) in relation to city logistics. After introducing vehicle routing and the main single-echelon problems and variants, the two-echelon version is presented and two different models proposed: one based on commodity flow and the other on vehicle flow modelling). Several instances are solved with those models and the results are compared and discussed. That comparison illustrates the difficulty of using this type of models to obtain results to that problem, and motivates the need of developing suitable algorithms. For that reason, an overview of heuristic methods to solve two-echelon vehicle routing problems is made, as well as an introduction of other related problems which are similar and interesting, relating in all cases the presented methods and problems to city logistics needs and goals.