Subgradient Methods for the Service Network Design Problem

Farvolden, Judith M.; Powell, Warren B.

doi:10.1287/trsc.28.3.256

Cited by 68 publications

(26 citation statements)

References 23 publications

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“…Farvolden and Powell [29] use subgradient-based heuristics for service network design in the motor carrier industry. They use duals from multicommodity flow problems to drive the selection of services using local search.…”

Section: Further They Develop Heuristic Algorithms and Analyze Theirmentioning

confidence: 99%

Composite Variable Formulations for Express Shipment Service Network Design

Armacost

Barnhart

Ware

2002

Transportation Science

137

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project 10704-0188], Washington, DC 20503. AGENCY USE ONLY (Leave blank)2. REPORT DATE 17.Jul.00 REPORT TYPE AND DATES COVERED DISSERTATION TITLE AND SUBTITLE COMPOSITE VARIABLE FORMULATIONS FOR EXPRESS SHIPMENT SERVICE NETWORK DESIGN AUTHOR(S)CAPT ARMACOST ANDREW P FUNDING NUMBERS PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) MASSACHUSETTS INSTITUTE OF TECHNOLOGY PERFORMING ORGANIZATION REPORT NUMBER SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)THE AbstractIn this thesis, we consider large-scale network design problems, specifically the problem of designing the air network of an express shipment (i.e., overnight) delivery operation. We focus on simultaneously determining the route structure, the assignment of fleet types to routes, and the flow of packages on aircraft. Traditional formulations for network design involve modeling both flow decisions and design decisions explicitly. The bounds provided by their linear programming relaxations are often weak. Common solution strategies strengthen the bounds by adding cuts, but the shear size of the express shipment problem results in models that are intractable.To overcome this shortcoming, we introduce a new modeling approach that 1) removes the flow variables as explicit decisions and embeds them within the design variables and 2) combines the design variables into composite variables, which represent the selection of multiple aircraft routes that cover the demands for some subset of commodities. The resulting composite variable formulation provides tighter bounds and enables very good solutions to be found quickly. We apply this type of formulation to the express shipment operations of the United Parcel Service (UPS). Compared with existing plans, the model produces a solution that reduces the number of required aircraft by almost 11 percent and total annual cost by almost 25 percent. This translates to potential annual savings in the hundreds of millions of dollars.We establish the composite variable formulation to be at least as strong as the traditional network design formulation, even when the latter is strengthened by Chvätal-Gomory rounding, and we demonstrate cases when strength is strictly improved. We also place the composite variable formulation in a more general setting by presenting it as a Dantzig-Wolfe decomposition of the traditional (intractable) network design formulation and by comparing com...

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Section: Further They Develop Heuristic Algorithms and Analyze Theirmentioning

confidence: 99%

Composite Variable Formulations for Express Shipment Service Network Design

Armacost

Barnhart

Ware

2002

Transportation Science

137

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“…Once developed, the train schedule is repeated every period (usually weekly) for a given time horizon (say, for a quarter of a year). Some recent references on this problem include Farvolden and Powell [16], Campbell [10], Kraft [23], and Brännlund et al [9].…”

Section: The Train Scheduling Problemmentioning

confidence: 99%

New approaches for solving the block‐to‐train assignment problem

2007

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Railroad planning involves solving two optimization problems: (i) the blocking problem, which determines what blocks to make and how to route traffic over these blocks; and (ii) the train schedule design problem, which determines train origins, destinations, and routes. Once the blocking plan and train schedule have been obtained, the next step is to determine which trains should carry which blocks. This problem, known as the block-to-train assignment problem, is considered in this paper. We provide two formulations for this problem: an arc-based formulation and a path-based formulation. The latter is generally smaller than the former, and it can better handle practical constraints. We also propose exact and heuristic algorithms based on the path-based formulation. Our exact algorithm solves an integer programming formulation with CPLEX using both a priori generation and dynamic generation of paths. Our heuristic algorithms include a Lagrangian relaxation-based method as well as a greedy construction method. We present computational results of our algorithms using the data provided by a major US railroad. We show that we can obtain an optimal solution of the block-to-train assignment problem within a few minutes of computational time, and can obtain heuristic solutions with 1-2% deviations from the optimal solutions within a few seconds.

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“…Haghani [39] [42], which provides a combined formulation of the service network design problem and shipment routing problem in a dynamic setting. They developed local-improvement heuristics to solve the resulting MCNF problem.…”

Section: Operational Planningmentioning

confidence: 99%

Dynamic Decision Making for Less-Than-Truckload Trucking Operations

Hejazi

Haghani

2007

Transportation Research Record: Journal of the Transportation R

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On a typical day, more than 53 million tons of goods valued at about $36 million are moved on the US multimodal transportation network. An efficient freight transportation industry is the key in facilitating the required movement of raw materials and finished products. Among different modes of transportation, trucking remains the shipping choice for many businesses and is increasing its market share.Less-than-truckload (LTL) trucking companies provide a transportation service in which several customers are served simultaneously by using the same truck and shipments need to be consolidated at some terminals to build economical loads.Intelligent transportation system (ITS) technologies increase the flow of available data, and offer opportunities to control the transportation operations in realtime. Some research efforts have considered real-time acceptance/rejection of shipping requests, but they are mostly focused on truckload trucking operations. This study tries to use real-time information in decision making for LTL carriers in a dynamically changing environment.The dissertation begins with an introduction of LTL trucking operations and different levels of planning for this type of motor carriers, followed by the review of literature that are related to tactical and operational planning. Following a brief discussion on multi commodity network flow problems and their solution algorithm, a mathematical model is proposed to deal with the combined shipment and routing problem.Furthermore, a decision making procedure as well as a decision support application are developed and are presented in this dissertation. The main step in the decision making procedure is to solve the proposed mathematical problem. Three heuristic solution algorithms are proposed and the quality of the solutions is evaluated using a set of benchmark solutions.Three levels of numerical experiments are conducted considering an auto carrier that operates on a hub-and-spoke network. The accuracy of the mathematical model and the behavior of the system under different demand/supply situations are examined. Also, the performance of the solutions provided by the proposed heuristic algorithms is compared and the best solution method is selected. The study suggests that significant reductions in operational costs are expected as the result of using the proposed decision making procedure.

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Subgradient Methods for the Service Network Design Problem

Cited by 68 publications

References 23 publications

Composite Variable Formulations for Express Shipment Service Network Design

Composite Variable Formulations for Express Shipment Service Network Design

New approaches for solving the block‐to‐train assignment problem

Dynamic Decision Making for Less-Than-Truckload Trucking Operations

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