During the last decades, the increase in railway traffic and train speeds has imposed more demanding conditions on railway bridges. For this reason, the ability to assess the dynamic behaviour of these critical structures has gained significant relevance to ensure the safety and functionality of the rail network. In this regard, European standards define strict criteria that must be thoroughly evaluated, often requiring the use of numerical models to asess bridge performance. However, modelling a train crossing on a bridge is not straightforward due to the complexity of the factors involved in this process. Among them, soil–structure interaction may have an important influence on the bridge response, especially in partially embedded structures such as portal frames [1]. This type of underpass constitutes one of the most common bridge types in modern railway lines. For this reason, its dynamic assessment is particularly relevant to ensure optimal design. In recent years, although a few studies have been devoted to the analysis of these structures, several challenges remain. First, the modal identification of portal frames can be difficult due to the high rigidity of these structures. Second, soil–structure interaction is often neglected due to its complexity and the typically high associated computational cost. In light of this, the dynamic behaviour of an existing portal frame raiwlay bridge used for high-speed traffic is investigated in this contribution. To this end, its modal parameters are first identified based on experimental data. Then, an efficient substructuring method [2] is employed to incorporate soil–structure interaction into the dynamic analyses. Special attention is paid to the evolution of the maximum vibrational response in terms of a few key parameters. [1] A. Zangeneh, S. François, G. Lombaert, C. Pacoste, “Modal analysis of coupled soil-structure systems”, Soil Dyn. Earthq. Eng., 144:106645 (2021). [2] J. Chordà-Monsonís, J.C. Sánchez-Quesada, E. Moliner, A. Romero, P. Galvín, M.D. Martínez-Rodrigo, “Efficient simulation of the soil–structure interaction on the dynamic response of a portal frame railway bridge”, Structures, 82:110600 (2025).