Required accuracy of information when determining optimal railway intervention programmes

Over the past decade, there has been a notable increase in mathematical models for determining optimal intervention programmes – that is, those with the highest net benefits. These increasingly sophisticated models rely on an increasing amount of accurate infrastructure information, which is often not available for infrastructure managers. They are, therefore, confronted with the question of which data they should collect and what accuracy these have to have in order that intervention programmes determined with sophisticated optimisation model are reliably optimal. In this paper, it is shown how infrastructure managers can estimate the required information accuracy when determining optimal railway intervention programmes. The required accuracy of the input information is defined by determining the ranges of values over which (a) the optimal intervention programme does not change, (b) the optimal intervention programmes can be considered similar and (c) the net benefit obtained by an intervention programme can be considered near optimal. The ranges are determined for one variable at a time considering the estimated values of the infrastructure manager as default values. The method is illustrated for a railway line in Switzerland using a constrained network flow model to determine the optimal intervention programmes.