Vibrations and re-radiated sound in the vicinity of Maglev-lines and methods for their reduction

Whereas the experience available with vibrations induced by trains had the chance to be developed during decades at the basis of measurements and accompanying engineering models, in the case of Maglev-systems a comparable "evolutionary" development of methods for prediction and abatement was not possible. However the lines cross urban areas and thus have to comply with limiting values relevant for new railway lines as far as the serviceability is concerned. Prototyping naturally has to be reduced to a minimum, so that the focus lies on robust theoretical models with an appropriate level of detailing, which on one hand side cope with the phenomena observed and on the other hand side give a certain freedom for competitive design and the adaption to the specific constraints by showing the key effects to be considered. The paper presents models for the prediction of the dynamic response of the track system in the frequency range relevant for vibrations and re-radiated sound. The elements of the models: guide-way, adjacent soil and moving oscillating load are explained. The calibration of the applied load with the various phenomena is based on theoretical investigations and extensive measurements that have been carried out in the scope of the planning of the Transrapid line in Munich/Germany. The effects caused by transient loading, roughness, spatial load distribution, parametric excitation and control loops are discussed. Possible measures for the abatement of vibrations necessary for guaranteeing serviceability requirements in sensitive areas are described. As those measures do not yet exist, a proposal for the procedure for their detailed design is illustrated. Insertion losses and limit values to be expected are shown.