A study on the effect of the asymmetry on real capacitated vehicle routing problems

Matrices with distances between pairs of locations are essential for solving vehicle routing problems like the Capacitated Vehicle Routing Problem (CVRP), Traveling Salesman Problem (TSP) and others. This work deals with the complex reality of transportation networks and asymmetry. Through a series of comprehensive and thorough computational and statistical experiments we study the effect that many factors like asymmetry, geographical location of the depot and clients, demand, territory and maximum vehicle capacity have in the solution of CVRP instances. We examine both classical heuristics as well as current state-of-the-art metaheuristics and show that these methods are seriously affected by the studied factors from a solution time and quality of solutions perspective. We systematically compare the solutions obtained in the symmetric scenario with those obtained in the real asymmetric case at a quantitative as well as a qualitative level, with the objective of carefully measuring and understanding the differences between both cases. © 2011 Elsevier Ltd.The authors are indebted to Keld Helsgaun, Stefan Ropke and especially to Yuichi Nagata for their kind help, collaboration and for facilitating the binaries of their algorithms. This work is partially funded by the Spanish Ministry of Science and Innovation, under the project "SMPA-Advanced Parallel Multiobjective Sequencing: Practical and Theoretical Advances" with reference DPI2008-03511/DPI. The authors should also thank the IMPIVA-Institute for the Small and Medium Valencian Enterprise, for the project TASER with reference IMDEEA/2011/142.Rodríguez Villalobos, A.; Ruiz García, R. (2012). A study on the effect of the asymmetry on real capacitated vehicle routing problems. Computers and Operations Research. 39(9):2142-2151. https://doi.org/10.1016/j.cor.2011.10.023S2142215139

Solving vehicle routing problems with asymmetric costs and heterogeneous fleets

[EN] The vehicle routing problem (VRP) is a flourishing research area with clear applications to real-life distribution companies. However, most VRP-related academic articles assume the existence of a homogeneous fleet of vehicles and/or a symmetric cost matrix. These assumptions are not always reasonable in real-life scenarios. To contribute in closing this gap between theory and practice, we propose a hybrid methodology for solving the asymmetric and heterogeneous vehicle routing problem (AHVRP). In our approach, we consider: 1) different types of vehicle loading capacities (heterogeneous fleets); 2) asymmetric distance-based costs. The proposed approach combines a randomised version of a well-known savings heuristic with several local searches specifically adapted to deal with the asymmetric nature of costs. A computational experiment allows us to discuss the efficiency of our approach and also to analyse how routing costs vary when slight departures from the homogeneous fleet assumption are considered.This work has been partially supported by the Ibero-American Program for Science, Technology and Development (CYTED2010-511RT0419, IN3-HAROSA network) and by the Spanish Ministry of Science and Innovation (TRA2010-21644-C03).Herrero, R.; Rodríguez Villalobos, A.; Cáceres-Cruz, J.; Juan, ÁA. (2014). Solving vehicle routing problems with asymmetric costs and heterogeneous fleets. International Journal of Advanced Operations Management. 6(1):58-80. https://doi.org/10.1504/IJAOM.2014.059620S58806