The European research project InBridge4EU (Enhanced interfaces and train categories for dynamic compatibility assessment for European railway bridges) intends to revise and propose methods to study the interface between railway bridges and rolling stock to harmonize standards across Europe and improve the design and maintenance of bridges in the context of interoperability. One work package of the project is focused on the study of the damping parameter since it is a key factor of dynamic behaviour of any structure. This paper describes the methodology used to extract the modal damping ratio parameter for hundreds of train passages over about 90 European railway bridges. Two methods were applied to extract damping data including a multi criteria and multi degrees-of-freedom optimization approach (MCO) and a covariance driven stochastic identification method (SSICOV). Complex bridge dynamics and interaction with train can involve several vibration modes, non-linear patterns and noisy data which complicate damping estimation, so reliability of both methods has been studied on artificial test-cases and on real signals benchmarks. The methodology applied to the project database is described and first results are presented and discussed. Additionally, two novel methods for automatic detection of the starting time of free-decay response are described. Next stages of the InBridge4EU project will exploit these data to propose revisions of normative damping values for railway bridges.