Trains cause dynamic excitations by crossing Railway bridges. Under certain circumstances, these excitations can lead to excessive vibrations of the structure. Due to the current state of European standards, the response of railway bridges to train crossings has to be determined by dynamic analysis, if specific parameters are complied. This master thesis introduces a calculation method consistent with European standards, that adapts the modal response spectrum analysis (as a specialized application of Ritz` and Galerkin's method) to simply supported girder systems. The vehicles are described as a series of forces, that move over the bridge girder with constant velocity. The results of the calculation method are combined in response spectrums and saved in a data base. The main part of this master thesis deals with the development and the functional principle of the software DynZugVergleich, that enables the evaluation of the response spectrums. This program provides the comparison of the dynamic response of simply supported girder bridges to different train models. Furthermore, the usage of DynZugVergleich is shown for an example of a real bridge structure.