Railroad Blocking: A Network Design Application

Barnhart, Cynthia; Jin, Hong; Vance, Pamela H.

doi:10.1287/opre.48.4.603.12416

Cited by 113 publications

(61 citation statements)

References 14 publications

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“…Path-based formulation is based on the column-generation formulation of the problem. Both types of formulations have been studied in Barnhart et al [6,7]. Although the difference between the two types has been well-established in terms of the size of the constraint set and the variable set of the corresponding linear programming formulations, we still provide a detailed discussion on the disadvantages of the arc-based formulation in our case.…”

Section: Mathematical Programming Formulationsmentioning

confidence: 97%

“…This paper formulates the blocking problem as a nonlinear mixed integer programming (MIP) problem, which simultaneously determines the optimal blocking strategies for all the classification yards in a railroad system. Some recent references on the blocking problem include Newton et al [26], Barnhart et al [6,7], and Ahuja et al [1].…”

Section: The Blocking Problemmentioning

confidence: 99%

“…This can be formulated as an IP problem in which we must decide whether an arc is in the path for a block. The arc-based formulation is considered as the conventional method for formulating a multicommodity network flow formulation (Barnhart et al [6,7]). We use the following notation in our arc-based IP formulation: Subject to…”

Section: Arc-based Ip Formulationmentioning

confidence: 99%

“…According to our problem formulation, the columns correspond to paths composed by one or more train arcs that are represented by the variables of the formulation. As discussed in Vance et al [28] and Barnhart et al [6,7], it is not always possible to obtain an integer feasible solution by solving the LP relaxation of the problem with column generation. Thus, the path based formulation for the multicommodity network flow problem has been used within a branch-and-price procedure.…”

Section: Optimal Solution Approachesmentioning

confidence: 99%

“…In our solution method, we use a similar setting as Barnhart et al [6,7] for the dynamic generation. However, to generate columns, we need to solve a constrained shortest path problem instead of the simple shortest path problem.…”

Section: Optimal Solution Approachesmentioning

confidence: 99%

See 4 more Smart Citations

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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Section: Mathematical Programming Formulationsmentioning

confidence: 97%

Section: The Blocking Problemmentioning

confidence: 99%

Section: Arc-based Ip Formulationmentioning

confidence: 99%

Section: Optimal Solution Approachesmentioning

confidence: 99%

Section: Optimal Solution Approachesmentioning

confidence: 99%

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

2007

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OR Models in Freight Railroad Industry

Nemani

Ahuja

2011

Wiley Encyclopedia of Operations Research and Management Science

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The transportation sector, especially the rail mode, is a very rich source of optimization problems and has been a primary focus of operations researchers. A plethora of articles dedicated to each transportation mode (rail, road, air, and water) can be found in the literature. Ironically, the industries are still using rules of thumb instead of mathematical models for most of the planning and scheduling processes. There are two main reasons for not using the operations research (OR) models: (i) the highly complex nature of the problems, and (ii) the huge gap between the academic (theoretical) and industrial (practical) approaches. With the steep growth in computational capabilities, we have started developing innovative algorithms by shifting the focus from finding optimal‐but‐impractical solutions to finding good‐and‐implementable solutions. We are developing state‐of‐the‐art ideas combining exact approaches such as network flows and mixed integer programming, with heuristics and meta‐heuristics such as the tabu search and the very large‐scale neighborhood (VLSN) search. In this article, we provide an overview of the railroad planning and scheduling problems at the strategic, tactical, and operational levels. We describe the best algorithms successfully implemented at US railroads, which have the potential of saving hundreds of millions of dollars annually.

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Operations Research for Freight Train Routing and Scheduling

Harrod

Gorman

2011

Wiley Encyclopedia of Operations Research and Management Science

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This article describes the service design activities that plan and implement the rail freight operating plan. Elements of strategic service design include the setting of train frequency, the routing of cars among trains, and the consolidation of cars, called blocking . At the operational level, trains are dispatched either according to train paths configured in advance, called timetables , or according to priority rules. We describe the North American and European practice along with selected modeling and problem solving methodologies appropriate for each of the operating conditions described.

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Railroad Blocking: A Network Design Application

Cited by 113 publications

References 14 publications

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

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

OR Models in Freight Railroad Industry

Operations Research for Freight Train Routing and Scheduling

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