Crew Scheduling and Rostering Problems in Railway Applications

Abstract

Crew planning is a typical problem arising in the management of large transit systems (such as railway and airline companies). Given a set of trips to be covered every day in a given period, the problem is to build a daily assignment of each trip to a crew so as to guarantee that all the trips are covered in the period at minimum cost. In practice, the overall crew management problem is decomposed into two subproblems, called crew scheduling and crew rostering. Crew scheduling deals with the short-term schedule of the crews: a convenient set of pairings is constructed, each representing a subset of trips to be covered by a single crew. Generally this subproblem is solved by generating a very large number of potential pairings, each with a given cost, and by selecting a minimum cost set of pairings covering all the trips. Crew rostering deals with the construction of a set of working rosters which determine the sequence of pairings that each single crew has to perform over the given time period, to cover every day all the pairings selected in the first phase. In this paper, we give an outline of different ways of modeling the two subproblems and possible solution methods. Two main solution approaches are illustrated for real-world applications. In particular we present the solution techniques currently adopted at the Italian railway company, Ferrovie dello Stato SpA, for solving the crew planning problem.