AMPL in Action

Strategic Planning of Train Crews

Dave Parkinson
BC Rail

Reprinted from Compass News, number 4, spring 1997

BC Rail, the third largest Canadian railroad, has recently implemented a decision support system, known as TCAPS (Train Crew Analysis and Planning System), as an aid to the strategic planning of train crews over its system. Train crew employment costs represent a significant portion of a railway's operating budget. Managers seek to ensure that an adequate supply of crews are available to meet expected demand. The temporal relationship between supply and demand is affected by several factors within management's control. They include decisions relating to annual vacation, retirements, employee training, hires, and layoffs. Given that costs are associated with each of these decisions, employment costs are related to the strategy employed.

Prior to development of this system, the process of crew management was considered reactive as opposed to proactive. Managers would bear upon this difficult problem using their experience and rules-of-thumb. Employment costs, while a consideration, were difficult to quantify. Considerable time, effort, and deliberation was required before a consensus regarding a "best" policy could be reached. Implementation of TCAPS eliminates this reaction lag and facilitates a shift toward the paradigm of proactive crew management and cost based decisions. Now users can perform "what-if" analyses and are able to determine the effects of a changing market demand on train crew supply within minutes.

The strategic manpower planning problem as it applies to railway crew management comprises the essential questions of:

The objective of the DSS is to define a minimum cost solution to these questions given the costs of employment, training, layoff, and overtime in response to estimates of crew retirements and planned train activity over an eighteen month planning horizon. In labor intensive union environments, seldom do "optimal" vacation strategies provide a workable solution. Deference to the status-quo is usually the rule and not the exception. A feature of TCAPS is that it allows a user the flexibility to exercise his or her judgment in the solution process by manually imposing vacation levels for any month of the planning horizon.

TCAPS was developed using a mix of Visual Basic and AMPL, operating in a Windows 95/Windows NT environment. Visual Basic modules are used for data collecting, processing, and creating an AMPL data file. After a data file is created, Visual Basic calls an AMPL run file that specifies the objective function, constraint matrix of the AMPL program, and appropriate solver directives (XA or CPLEX). After a solution is obtained, the user is returned to the Visual Basic environment where the solution is viewed. The choice of Visual Basic/AMPL provides tremendous ease in both program development and maintenance. Changes to the mathematical model are implemented quickly using AMPL, while changes to the data file are implemented with minimal effort using Visual Basic.

Author Dave Parkinson is a Senior Operations Analyst - Service Planning for BC Rail. Dave has 20 years of experience as a Rail Traffic Controller and 4 years as an Analyst in Operations Research / Service Planning. His primary role at BC Rail is to develop methods of enhancing profitability through innovation. As a practitioner of OR and Finance, he makes frequent use of mathematical programming. Dave says, "AMPL is my choice of modeling languages and has been since 1993."

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