Experimental and theoretical analysis of railway bridge noise reduction using resilient rail fasteners in Burgdorf, Switzerland

The increased noise level as trains travel over bridges is, in many situations, a source of disturbance for nearby residents. As well as the rolling noise radiated by the wheel and track, the vibration generated at the wheel-rail interface also propagates into the bridge structure and the vibration response of the components of the bridge is an important extra source of noise compared with tracks at-grade. Vibration isolation of the bridge structure from the rail is therefore used to reduce noise. This often takes the form of resilient rail fasteners. Two different elastic rail fastenings were therefore tested on a twin track bridge by the Swiss Railways (SBB). The bridge over the river Emme at Burgdorf, is a ballastless steel bridge with timbers between the rail fastener and the bridge. Hanging steel sleepers have been added between the wooden sleepers on which the track is supported to form a continuous deck under the track. To find the best elasticity for the rail fasteners, predictions of the bridge noise were made using the Norbert model. Measurements were made on the bridge with the track in its original state to provide parameters for the model. These included rail and sleeper vibration as well as pass-by noise from service passenger and freight trains at different speeds. For the two tracks, elastic rail fasteners from two suppliers were installed. The measurement after installation showed a clear noise reduction for the frequency range from 80 to 400 Hz of about 10 dB. However the reduction in A-weighted overall noise level is in the range of 2 to 4 dB, as indicated by the model. The results show similar reduction for both systems.