Making comparable risk estimates for railway assets of different types

Railway managers plan interventions on infrastructures to reduce risks. To plan these interventions effectively, they need comparable risk estimates for all the assets, by considering all types of failure causes and failure modes and all the costs and effects on stakeholders due to these failures. However, existing risk models have been developed for specific asset types and specific failure scenarios, and they result in a wide range of qualitative and quantitative results that are not compatible. Hence, often managers cannot use the results of these models directly in an aggregated assessment to prioritise risk-reducing interventions across a network effectively. This paper presents a methodology for using results from existing models in a systematic way to produce comparable risk estimates for different asset types. Although the methodology is based on simple standard tools, it is the first time that they have been brought together in a way that will help infrastructure managers make consistent risk estimates by systematically determining scenarios related to asset failures and estimating their effects on the railway service in comparable units. The usefulness of the methodology is demonstrated by using it to produce comparable risk estimates for the track, switches and bridges of a part of an Irish network.