The purpose of this study is to propose a novel hybrid dynamic probability-based failure analysis technique consisting of dynamic Bayesian discretization (DBD) and stochastic Petri nets (SPNs) for railway rolling stock (RS) failure analysis. Performing failure analysis and diagnoses for integrated RS subsystems is challenging and can lead to operational delays affecting fleet reliability and availability. This paper presents an integrated feature of updative adaptation using DBD methods to analyze prior continuous and discrete probability data-by means of evidence-based propagation to ascertain posterior faulty component states and simultaneously allowing for rapid failure notification, detection, and isolation of multiple RS subsystems using the reachability tree characteristics of SPNs. Unlike other dynamic probability methods, the DBD-SPN hybrid model presented here reduces computational time and enhances convergence accuracy using the Kullback-Leibler measure, sequential event analysis, and stable and low-entropy-error characteristics. In an extensive UK-based RS case study, it was observed that this approach is suitable for rapid failure notification, detection, and isolation of traction door interlock failure. It is also believed that the current study represents a useful contribution to the research and technology of hybrid DBD and SPNs for the failure analysis of a system consisting of multiple subsystems, since its application makes the difference between being able to evaluate realistically common cause and sequential failure analyses of complex systems.

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Complex engineering systems include several subsystems that interact in a stochastic and multifaceted manner with multiple failure modes (FMs). The dynamic nature of FMs introduces uncertainties that negatively impact the reliability, risk, and maintenance of complex systems. Traditional approaches of adopting standalone techniques for managing FMs independently at various stages of the asset life cycle pose challenges related to utilisation, costs, availability, and in some cases, accidents. Therefore, this paper proposes a composite hybrid framework comprising four independent hybrid models for comprehensive through-life failure management and optimisation. The first hybrid model entails failure mode, effects, and criticality analysis (FMECA) and fault tree analysis (FTA) to identify critical FMs and overall subsystem failure rates. The second hybrid model analyses FMs caused by multiple subsystems using hybrid dynamic Bayesian discretisation. The third hybrid model adopts a hybrid Gaussian process regression machine learning technique to evaluate wear loss. The fourth hybrid model evaluates the overall risk using a Bayesian factorisation and elimination method based on multiple failure causes. Finally, a decision-making step is used to evaluate the results of the previous four steps to decide an appropriate maintenance strategy. The proposed method is verified through a case study of a UK-based train operator's pantograph system. The results show that the maintenance inspection intervals and strategy obtained using the proposed framework strike a good balance between safety and fleet availability.

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Railway transport system (RTS) failures exert enormous strain on end-users and operators owing to in-service reliability failure. Despite the extensive research on improving the reliability of RTS, such as signalling, tracks, and infrastructure, few attempts have been made to develop an effective optimisation model for improving the reliability, and maintenance of rolling stock subsystems. In this paper, a new hybrid model that integrates reliability, risk, and maintenance techniques is proposed to facilitate engineering failure and asset management decision analysis. The upstream segment of the model consists of risk and reliability techniques for bottom-up and top-down failure analysis using failure mode effects and criticality analysis and fault tree analysis, respectively. The downstream segment consists of a (1) decision-making grid (DMG) for the appropriate allocation of maintenance strategies using a decision map and (2) group decision-making analysis for selecting appropriate improvement options for subsystems allocated to the worst region of the DMG map using the multi-criteria pairwise comparison features of the analytical hierarchy process. The hybrid model was illustrated through a case study for replacing an unreliable pneumatic brake unit (PBU) using operational data from a UK-based train operator where the frequency of failures and delay minutes exceeded the operator’s original target by 300% and 900%, respectively. The results indicate that the novel hybrid model can effectively analyse and identify a new PBU subsystem that meets the operator’s reliability, risk, and maintenance requirements.