Vehicle Routing Problem Vehicle Routing Problem Edited by Tonci Caric and Hrvoje Gold I-Tech IV Published by In-Teh In-Teh is Croatian branch of I-Tech Education and Publishing KG, Vienna, Austria. Abstracting and non-profit use of the material is permitted with credit to the source. Statements and opinions expressed in the chapters are these of the individual contributors and not necessarily those of the editors or publisher. No responsibility is accepted for the accuracy of information contained in the published articles. Publisher assumes no responsibility liability for any damage or injury to persons or property arising out of the use of any materials, instructions, methods or ideas contained inside. After this work has been published by the In-Teh, authors have the right to republish it, in whole or part, in any publication of which they are an author or editor, and the make other personal use of the work. © 2008 In-teh www.in-teh.org Additional copies can be obtained from: [email protected] First published September 2008 Printed in Croatia A catalogue record for this book is available from the University Library Rijeka under no. 111225011 Vehicle Routing Problem, Edited by Tonci Caric and Hrvoje Gold p. cm. ISBN 978-953-7619-09-1 1. Vehicle Routing Problem. Tonci Caric and Hrvoje Gold Preface The Vehicle Routing Problem (VRP) dates back to the end of the fifties of the last century when Dantzig and Ramser set the mathematical programming formulation and algorithmic approach to solve the problem of delivering gasoline to service stations. Since then the interest in VRP evolved from a small group of mathematicians to the broad range of researchers and practitioners, from different disciplines, involved in this field today. The VRP definition states that m vehicles initially located at a depot are to deliver discrete quantities of goods to n customers. Determining the optimal route used by a group of vehicles when serving a group of users represents a VRP problem. The objective is to minimize the overall transportation cost. The solution of the classical VRP problem is a set of routes which all begin and end in the depot, and which satisfies the constraint that all the customers are served only once. The transportation cost can be improved by reducing the total travelled distance and by reducing the number of the required vehicles. The majority of the real world problems are often much more complex than the classical VRP. Therefore in practice, the classical VRP problem is augmented by constraints, such as vehicle capacity or time interval in which each customer has to be served, revealing the Capacitated Vehicle Routing Problem (CVRP) and the Vehicle Routing Problem with Time Windows (VRPTW), respectively. In the last fifty years many real-world problems have required extended formulation that resulted in the multiple depot VRP, periodic VRP, split delivery VRP, stochastic VRP, VRP with backhauls, VRP with pickup and delivering and many others. VRP is NP hard combinatorial optimization problem that can be exactly solved only for small instances of the problem. Although the heuristic approach does not guarantee optimality, it yields best results in practice. In the last twenty years the meta-heuristics has emerged as the most promising direction of research for the VRP family of problems. This book consists of nine chapters. In the first four chapters the authors use innovative combinations of methods to solve the classically formulated VRP. The next two chapters study the VRP model as a tool for formalizing and solving problems not often found in the literature. The solving procedures in the next two chapters use the evolutionary multi- criteria optimization approach. The last chapter is focused on multi-resource scheduling problem. A brief outline of chapters is as follows: Chapter 1 “Scatter Search for Vehicle Routing Problem with Time Windows and Split Deliveries” considers the scatter search as a framework which provides a means to combine solutions, diversify, and intensify the meta-heuristic search process. The initial solution is an extension of Solomon’s sequential insertion heuristic I1. The experiments are carried out on Solomon’s problems with augmented demands which allow more than one delivery per customer. Chapter 2 “A Modelling and Optimization Framework for Real-World Vehicle Routing Problems” presents an integrated modelling and optimization framework for solving VI complex and practical VRP. The modular structure of the framework, a script based modelling language, a library of VRP related algorithms and a graphical user interface give the user both reusable components and high flexibility for rapid prototyping of complex VRP. The algorithm and the performance measure protocol is explained and implemented on the standard benchmark and on practical VRPTW problems. Chapter 3 “An Effective Search Framework Combining Meta-Heuristics to Solve the Vehicle Routing Problems with Time Windows” mainly considers combining of the two well-known methods (guided local search and tabu search) for solving VRPTW where the choice of the search method in each iteration is controlled by simulated annealing. The initial solution is obtained by push-forward insertion heuristics and the virtual vehicle heuristics. The approach is verified on the standard Solomon’s benchmark. Chapter 4 “A Hybrid Ant Colony System Approach for the Capacitated Vehicle Routing Problem and the Capacitated Vehicle Routing Problem with Time Windows” deals with hybrid ant colony with local search as the mechanism to solve CVRP and CVRPTW problems. 2-opt and saving heuristics participate in hybridization. To improve the solution the algorithm introduces the simulated annealing in the phase of the pheromones updating. Hybrid Ant Colony System is tested on the classical CVRP and VRPTW problems. Chapter 5 “Dynamic Vehicle Routing for Relief Logistics in Natural Disasters” examines the dynamic vehicle routing problem for relief logistics (DVRP-RL) in natural disasters as a support to the relief management. Two-phase heuristic, route construction and route improvement for DVRP-RL is proposed. The solution procedure resolves the current change of constraints generated by new events in the field in such a way which updates information in DVRP-RL and initiates route construction or route improvement. Differences between features of VRPTW and DVRP-RL are presented. Routing of vehicles in constrained environment of emergency is computed and analysed. Chapter 6 “Cumulative Vehicle Routing Problems” develops formulation of cumulative VRP, named CumVRP, which is based on capacitated VRP extended by the cost function defined as a product of the distance travelled and the flow on that arc. m-Travelling Repairman Problem, Energy Minimizing Vehicle Routing Problem and Average Distance- Minimizing School-bus Routing Problem can be formulated as the special cases of CumVRP. Numerical examples of CumVRP formulation focusing on the collection case of the Energy Minimizing VRP are provided. Chapter 7 “Enhancing Solution Similarity in Multi-Objective Vehicle Routing Problems with Different Demand Periods” describes the problem of multiple-objective VRP constituted of two periods with different demands. The objectives are minimization of the maximum routing time, minimization of the number of vehicles and maximization of the similarity of solutions. To obtain a similar set of solutions in the normal and high demand period two-fold evolutionary multi-criteria optimization algorithm is applied. The simulation result on a multi-objective VRP with two periods with different demands are presented. In Chapter 8 “A Multiobjectivization Approach for Vehicle Routing Problems” the single-objective optimization CVRP problem is translated into multi-objective optimization problem using the concept of multiobjectivization. On the translated problem the evolutionary multi-criteria optimization algorithm is applied. Experimental results indicate that multiobjectivization using additional objectives is more effective than using either objective alone. VII Chapter 9 “Resources Requirement and Routing in Courier Service” studies multi- resource scheduling in pickup and delivery operations occurring mostly in the courier service. The objective is to examine the possible cost savings and computational time required as delivery resources operate in some cooperative modes. Computational analysis based on the real-life and simulated data is carried out. This book presents recent improvements, innovative ideas and concepts regarding the vehicle routing problem. It will be of interest to students, researchers and practitioners with knowledge of the main methods for the solution of the combinatorial optimization problems. July 2008 Editor Tonči Carić Hrvoje Gold Uniaversity of Zagreb Faculty of Traffic and Transport Sciences Vukelićeva 4, HR-10000 Zagreb, Croatia Contents Preface V 1. Scatter Search for Vehicle Routing Problem with Time Windows 001 and Split Deliveries Patrícia Belfiore, Hugo Tsugunobu and Yoshida Yoshizaki 2. A Modelling and Optimization Framework for Real-World 015 Vehicle Routing Problems Tonči Carić1, Ante Galić, Juraj Fosin, Hrvoje Gold and Andreas Reinholz 3. An Effective Search Framework Combining Meta-Heuristics to Solve the 035 Vehicle Routing Problems with Time Windows Vincent Tam and K.T. Ma 4. A Hybrid Ant Colony System Approach for the Capacitated Vehicle 057 Routing Problem and the Capacitated Vehicle Routing Problem with Time Windows Amir Hajjam El Hassani,