Identifying fundamental changes by structural transformation processes of railway bridges Railway bridges need to be repaired and upgraded several times during their service life, until they are replaced by new bridges. These measures are not only done for technical reasons or when the structure has reached the end of its service life. It can also be for economic or political reasons, such as the expansion of the rail network. This article deals with the changes that have been made to sample bridges during their service life. The changes are documented and presented in a coherent manner, allowing insights to be gained. The construction measures can be placed in context and classified historically. This article presents the analysis, the methods which have been used and the results. As part of the research project “Railway bridges – monuments in the network”, railway bridges are analysed and classified in terms of construction history as an integral part of the overall railway system.