In the context of di!erent railway infrastructure projects in Switzerland new standards for vibration mitigation measures have to be developed and introduced for various track systems, sites and conditions: tunnel and surface lines, ballasted or slab track, low and high speed, light and heavy vehicles. Earlier applications of mats under ballast showed that the ballasted track on a softer subgrade became instable. Therefore, as a "rst step the technical feasability of new layouts and their stability had to be tested, especially for mixed tra$c of high speed and heavy trains on ballasted surface lines. Long-term behaviour and e!ectiveness of installed mass}spring systems in S-Bahn tunnels were reviewed and served as a basis for extrapolation for newer developments under other conditions. For technical system optimization the exact understanding of the forces and movements is important; this will be further investigated within the framework of RENVIB II on installations located and tested in Switzerland. It is important for the future of railways both to reduce the impact of the vibration and structure-borne noise of rail systems on the neighbourhood and to minimize the cost of installation and maintenance of possible insulation systems. In order to achieve this, a reasonable cost}bene"t relation must be predicted.