Low frequency modeling: Comparison between standard methods and a local procedure on standard testing scenarios

Member States are drawing up action plans to mitigate noise exposure according requirements of the Environmental Noise Directive: however, low frequency noise is hard to be tackled especially because noise barriers are often not efictive. In fact, some studies demonstrated that the installation of a barrier decreases the low frequencies masking efiect due to presence of high ones. Therefore, annoyance and complaints may rise despite having spent money for mitigation. There should be methods allowing noise action planners to take into account this efiect so that they can estimate with spectral detail the mitigation available solutions, included barrier installation. In this paper we compare data in terms of A-weighted levels and C-weighted levels to estimate low frequency relevance. Difierent methods capable of mapping frequency detail of road trafic noise are tested: in particular we compare data from interim method NMPB 96, Dutch RMR method and the ones available from a customized procedure, which starts from Statistical Pass By regional data and use the ISO 9613 standard to propagate noise. Moreover, difierent scenarios will be analysed according those selected by Joint Research Centre to evaluate noise on a complex scenario (freefield, barriers, buildings, screened buildings) so that a large variety of trafic and environment conditions are tested. Using difierence between methods it will be possible to assess level of uncertainty of mapping procedure.