Derivation of train track isolation requirement for a steel road bridge based on vibro-acoustic analyses

The paper reports on a hybrid method, aimed at predicting the expected noise emission of the structure-borne component of a combined bridge/track system, currently under development. The method is based on detailed vibro-acoustic analyses of the bridge and consists of three major elements: experimental estimation of input dynamic forces generated by rolling of trams along the track; a detailed analysis of the steel box girder bridge structure based both on experiments and numerical calculations; and estimation of sound radiation from the bridge structure performed by means of boundary element methods and validated on the bridge by vibro-acoustic measurements. The proposed method was used for the hypothetical case that no vibration isolation is installed and it was established that at least 10–12 dB(A) noise reduction is required. As reported elsewhere, the calculation can be repeated for isolated tracks and the efficiency of various track design versions can be evaluated.