Forced vibration tests are applied to railway filler beam bridges of different span length, bearing condition and construction type, aiming to determine the bridge specific dynamic parameters. The main focus of the research is the determination of the actual present vibration mode dependent damping ratios, whereby a statistical method is applied to account for the regularly observed scattering of experimentally determined damping ratios of real structures. The first part of the paper describes the method applied to extract the dynamic parameters by application of forced vibration tests and in the second part a representative number of measured railway bridges is presented and discussed in detail. It is shown that the application of forced vibration tests lead to reliable and reproducible results for the experimentally determined dynamic parameters of real railway bridges, especially of the damping ratios, and that the applied statistical method accounts sufficiently for the spreading of the determined damping values. In addition, the experimentally gained results show that both, the natural frequencies and especially the damping ratios of the considered railway filler beam bridges depend highly on the executed bridge specific bearing conditions. A continuous line bearing contributes highly to the energy dissipation and lead to significant higher damping ratios of railway bridges compared to the common executed elastomeric point bearings. The experimentally determined damping ratios are compared with the values given in the Eurocode and based on the gained results the aim is to develop and define an additional damping applicable to increase the normative lower limit damping ratios for filler beam bridges.