Introducing a preliminary consists selection in the locomotive assignment problem

• Methodologically, we innovate the LAP solution by integrating planning and routing.
• We analyze fuel exploitation and consist homogeneity not featured in previous models.
• We have potential savings in routing by accounting for fueling constraints in the LPP.
• Potential savings concentrate on Intermodal trains, few consist changes are required.
• Locomotive managers can optimally select consist types for the LPP solution.

The Locomotive Assignment Problem (LAP) is a class of planning and scheduling problems solved by assigning a fleet of locomotives to a network of trains. In the planning versions of the LAP, the type of consist (a group of linked locomotives) assigned to each train in a given schedule is determined. We introduce an optimization model (called consists selection) that precedes the planning LAP solution and determines the set of consist types. This selection leads to solutions that are characterized by potential savings in terms of overall fueling cost and are easier to handle in the routing phase.