Robert A. Russell

SIMULATED ANNEALING METAHEURISTICS FOR THE VEHICLE ROUTING PROBLEM WITH TIME WINDOWS

This paper develops simulated annealing metaheuristics for the vehicle routing and scheduling problem with time window constraints. Two different neighborhood structures, the λ-interchange mechanism of Osman and thek-node interchange process of Christofides and Beasley, are implemented. The enhancement of the annealing process with a short-term memory function via a tabu list is examined as a basis for improving the metaheuristic approach. Computational results on test problems from the literature as well as large-scale real-world problem are reported. The metaheuristics achieve solutions that compare favorably with previously reported results.

An assignment routing problem

ABSTRACT This paper examines a routing design problem in which the objective is to assign customer demand points to days of the week in order to solve the resulting node routing problems over the entire week most effectively. The emphasis is on obtaining approximate solutions for this type of combinatorial problem. Several heuristics are developed and tested on a large scale refuse collection problem. Computational results, as well as a discussion of expected benefits, are presented.

Scatter search for the vehicle routing problem with time windows

In this paper we use a scatter search framework to solve the vehicle routing problem with time windows (VRPTW). Our objective is to achieve effective solutions and to investigate the effects of reference set design parameters pertaining to size, quality and diversity. Both a common arc method and an optimization-based set covering model are used to combine vehicle routing solutions. A reactive tabu search metaheuristic and a tabu search with an advanced recovery feature, together with a set covering procedure are used for solution improvement. Our approach led to a robust solution method, generating solution quality that is competitive with the current best metaheuristics.

Devising a Cost Effective Schedule for a Baseball League

In this paper, we discuss the problem of devising a cost effective schedule for a baseball league. Sports scheduling is a notoriously difficult problem. A schedule must satisfy constraints on timing such as the number of games to be played between every pair of teams, the bounds on the number of consecutive home (or away) games for each team, that every pair of teams must have played each other in the first half of the season, and so on. Often, there are additional factors to be considered for a particular league, for example, the availability of venues on specific dates, home-game preferences of teams on specific dates, and balancing of schedules so that games between two teams are evenly-spaced throughout the season. In addition to finding a feasible schedule that meets all the timing restrictions, the problem addressed in this paper has the additional complexity of having the objective of minimizing travel costs. We discuss some structural properties of a schedule that meets the timing constraints and present two heuristics for finding a low-cost schedule. The methodology is used to develop an improved schedule for the Texas Baseball League.

Solving Constrained Transportation Problems

This paper presents a specialized method for solving transportation problems with several additional linear constraints. The method is basically the primal simplex method, specialized to exploit fully the topological structure embedded in the problem. It couples the poly-ω technique of Charnes and Cooper with the row-column sum method to yield an “inverse compactification” that minimizes the basis information to be stored between successive iterations, and in addition minimizes the arithmetic calculations required in pivoting. In particular, the solution procedure only requires the storage of a spanning tree and a (q + 1) × q matrix (where q is the number of additional constraints) for each basis. The steps of updating costs and finding representations reduce to a sequence of simpler operations that utilize fully the triangularity of the spanning tree. Procedures for obtaining basic primal “feasible” starts are also presented.

Integrating multi-product production and distribution in newspaper logistics

This paper presents a tabu search metaheuristic to aid in the coordination and synchronization of the production and delivery of multi-product newspapers to bulk delivery locations. The problem is modeled as an open vehicle routing problem with time windows and zoning constraints. The methodology is applied to the newspaper production and distribution problem in a major metropolitan area. Computational results are presented and show significant improvement relative to an existing newspaper companys operations.

A multiphase approach to the period routing problem

In this article, we present a multiphase approach to the period routing problem. The period routing problem involves the design of effective vehicle routes that satisfy customer service frequencies over a specified planning horizon. The first phase of analysis consists of a generalized network approximation to achieve an efficient initial solution. The second phase involves an interchange heuristic that reduces distribution costs by solving a surrogate traveling salesman problem. The third phase consists of an interchange heuristic that further reduces the distribution costs by addressing the actual vehicle routes of the period routing problem. A fourth phase utilizes a 0–1 integer model to attempt further improvements. Computational results on test problems indicate that the multiphase approach yields improvements over previous best solutions.

Scheduling sports competitions on multiple venues

Abstract The scheduling of sports competitions has recently been receiving a great deal of attention in the operational research literature. This research considers the scheduling of competitions that take place on several venues not associated with any of the participants. It was motivated by the request from a head coach of a major-college football team to assist in the development of a training schedule for intra-squad team competitions on various drill stations. An integer goal program is developed to construct a schedule that satisfies a variety of conditions.

A metaheuristic for the vehicle-routeing problem with soft time windows

This paper develops a metaheuristic for the vehicle-routeing and scheduling problem with soft time window constraints. A tabu search solution method is developed, which utilizes a mixed neighbourhood structure and an advanced recovery procedure to generate high-quality solutions. Computational results on test problems from the literature are reported. The metaheuristic achieves solutions that compare favourably with previously reported results.

Integrating purchasing and routing in a propane gas supply chain

Abstract This paper addresses the integration of purchasing and routing for a propane gas supply chain. The focus is on the wholesale side of the supply network. Rigorous solution methods using both set partitioning and tabu search are developed for obtaining optimal and near-optimal solutions for the purchasing/routing problem. The proposed methods are applied to a real-world propane distribution problem. The results of the study indicate that the potential annual cost savings through the integration of purchasing and routing decisions can range up to millions of dollars for large distributors. The methods can also be used strategically as an aid in reconfiguring the supply network involving depot locations, tanker fleet sizing, and allocation of capacity at supply terminals. The methodology could also be used to provide decision support for distributing other energy products such as heating oil.