Objectives and methods in multi-objective routing problems: a survey and classification scheme

Transportation of goods and passengers plays an important role for companies and individuals in today's globalized world. There exists a variety of road-based routing problems at all three strategic, tactical and operational planning levels. Examples include location routing problems, fleet management, vehicle routing and shortest path problems. To evaluate solution quality, multiple, usually conflicting objectives are considered. Aiming to provide practice-oriented decision support, multi-objective routing problems attract more and more attention in academic literature. This contribution offers a wide overview of which application-oriented multi-objective routing problems are treated and what kind of trade-off is investigated. Furthermore, the algorithmic approach is analyzed with regard to its fitness assignment strategy, i.e. how the multiple objectives are handled, and its search strategy to solve the problem. In order to structure the literature, we propose a classification in which every identified objective is sorted into a category and related to problem elements. Both problem-specific and general research gaps in multi-objective routing problems are identified and offer a starting point for future research. Lastly, fitness assignment strategies are extensively discussed and insights regarding their usage are given. (C) 2020 Elsevier B.V. All rights reserved.