Optimal computer scheduling of engine drivers

This paper presents a method to determine an optimal work roster for engine drivers of any rail network, dependent on a given central station. The main criterion in achieving optimality consists in minimizing the time spent in inactive duty. The existence of different types of trades union rules has induced us to divide the problem into three stages. The first consists in calculating an optimal set, R, of round trips and the second in using R to construct an optimal set, S, of single services. Each element of S comprises either one, two or three elements of R. In both these stages, only trade union rules involving single services are taken into account, and linear programs must be solved. The third stage consists in using all the elements of S to construct an optimal sequence, i.e. the cyclic roster required. In this case, only trade union rules involving sequences of services are considered. The procedure described in this paper has been executed as part of a project commissioned by the Italian state Railways (F.S.). Examples of relevant printouts are included.