A Risk-informed Framework for Maintenance Decision-making of Railways Over Bridges Under Seismic Influence

This work presents a risk-informed framework to allow for the introduction of an external risk scenario resulting from the seismic influence of railways on supporting structures. Previous traditional performance-based railway asset management approaches often separate operational degradation from external hazard effects, which limits efficient decision-making regarding appropriate maintenance strategies. The framework considered the probabilities of seismic events occurring on a selected bridge and their translated impact on the railway track. The proposed framework integrates the effects of seismic influence on the baseline asset degradation trajectory, obtained using a continuous-time Markov deterioration process. The hazard component is modelled using a Poisson distribution for earthquake occurrence frequency, coupled with a truncated normal distribution of magnitudes to estimate the likelihood of different seismic intensities. Afterwards, fragility curves were obtained to assess the occurring probabilities of exceeding damage states. By performing a static non-linear analysis on the bridge, the spectral displacements of each damage state were translated into deterioration rate multipliers, producing updated deterioration curves. Further, the expected risk for the railway line is computed as the product of the probability of each damage state and its corresponding consequence, expressed in terms of repair cost, downtime or functional loss, based on available data and the preference of the asset manager. This framework provides a quantitative basis for comparing maintenance interventions. Improvement assumptions are made for preventive, corrective and replacement maintenance strategies to evaluate their efficiency in limiting the expected risk. The results justified how introducing hazard-based assessment can significantly alter baseline trajectories and associated risk profiles, highlighting the importance of linking structural fragility to long-term performance models. The framework improves decision-making for asset managers by integrating a hazard-based risk assessment into the deterioration model and will contribute to providing asset managers with a more efficient tool for planning interventions on railway bridges.

Keywords: Key Performance indicators (KPIs), Asset management, Risk-informed Decision-making, Railway performance, Bridge safety and Durability..