Acoustic Effectivity of Old Noise Barriers

Over time, different kinds of defects can appear at noise barriers. The presented project was meant to examine the influence of those defects on the acoustical behaviour of noise barriers and to provide a catalog which enables the prediction of the influence of specific defects especially on the sound insulation of the noise barrier. Based on the information contained in the catalog, it should be possible to provide cost efficient action to permanently ensure the protection of immission sites. To compile the catalog, the German sound propagation model of the RLS 90 has been extended by the description of the sound transmission through the noise barrier together with the geometrical consideration of leakages in the shape of holes and slits. In the presentation it will be shown that the transmission coefficient of leakages can be predicted reliably by means of the calculation according to MECHEL as well as by measurements at noise barriers in situ. Furthermore, the latter ones have been used to successfully validate the models applied to describe the sound transmission coefficient of leakages and the sound propagation behind noise barriers in consideration of the transmission.