Towards improved normative definitions of damping in railway bridges: Insights from the InBridge4EU European experimental database

Recent measurement campaigns under the Shift2Rail In2Track2 and In2Track3 projects have shown that damping levels in existing railway bridges often exceed the conservative values prescribed in EN 1991–2. These studies also revealed significant scatter among similar structures, reflecting the complex influence of soil–structure interaction, vibration amplitude, and estimation methods. Given the critical role of damping in bridge dynamics, particularly near resonance, and in light of the challenges outlined above, an update of the Eurocode provisions is needed. In this context, the European Union Agency for Railways (ERA) and Europe’s Rail Joint Undertaking (EU-Rail) launched the InBridge4EU project to improve the representation of damping in the Eurocode framework. This paper presents its main outcomes based on over 1150 traffic-induced acceleration records from nearly 90 bridges across five European countries. The analysis resulted in the first proposal since the 1990s for revised damping curves and an updated bridge typology classification that better reflects real-world variability. These results provide a more robust, data-driven basis for the forthcoming revision of EN 1991–2, enabling less conservative yet safe design approaches and contributing to more efficient and reliable dynamic assessment of railway bridges in the European network. • 1150 records from 89 bridges underpin revised Eurocode damping curves. • New portal frame category proposed with higher damping for short spans. • Prestressed concrete merged with reinforced/filler-beam for unified guidance. • Composite preliminarily separated from steel with higher damping for long spans. • Data-driven approach reduces conservatism in EN 1991–2 design of railway bridges.