Innovative measures for reducing noise radiation from steel railway bridges

Abstract

In the course of a large, government-financed project, infrastructure-related innovative measures for the reduction of railway noise and vibrations were installed and tested at numerous hotspots. The demonstrated effects will be the basis for the formal recognition of these technologies. On behalf of DB Netz (infrastructure) DB Systemtechnik set up a measurement concept and supported the acoustic investigations. This paper focusses on those measures to reduce the noise of steel bridges. For the first time, the investigations carried out with resilient rail fastening systems on steel bridges with directly fastened track show an effect in the lower frequency range. The measures used in addition to the resilient rail fasteners, such as the elastically mounted covers, the filling of the bridge railing as a sound barrier and the use of rail dampers can further reduce the noise next to the bridge. For steel bridges with ballasted tracks, the effect of homologated under-sleeper pads in the lower frequency range is not comparable to that of under-ballast mats. If combined with bridge dampers however, the effect is significant. The use of bridge dampers alone requires careful tuning to the bridge resonance frequencies. Since they only affect the rolling noise, rail dampers have only a small influence on the overall bridge noise.