Since the German 24. BImSchV came into force, discussion arose whether the required sound insulation of the building is ensured by the correction 'E'. In a first step, emission spectra of different motor vehicles were evaluated considering different pavements and speeds. From these, four clearly distinguishable emission spectra were composed. Noise propagation calculations were carried out as well using a modified line source in the section method according to DIN ISO 9613-2:1999-10 in one-third octave bands as using the national German road noise calculation methods ('Richtlinien für den Lärmschutz an Straßen - RLS-90'). A combination of these emission spectra with 41 propagation situations with a variance in ground attenuation, distances and obstacles could be aggregated to 83 distinguishable spectra in front of the façade. Combined with 1.043 different sound insulation spectra of windows, 86.569 spectral indoor sound levels were obtained. The sound level after transmission through a closed window shows a different spectral composition than the sound levels in front of a window. This leads to a difference of sound levels indoors between calculations with a singular value A-rated value (Rw) compared to one-third octave bands. The calculations with one-third octave bands are supposed to be more accurate. The A-rated results must be adjusted, the correction summand E of the 24. BImSchV aims to do this. Generalized, the resulting correction summand E is about 3 dB above the values mentioned in Table 2 of the 24. BImSchV. The definition of 'rural roads' has to be changed. A distinction between 'roads with a speed limit of 70 km/h or higher without open porous asphalt' and 'all other roads'. Alternatively, a sufficient sound protection can be achieved using the spectral adaption value Ctr,50-3150. Values in Table 2 could be left unchanged. Instead of the singular value for sound insulation Rw of the window the term Rw + Ctr,50-3150 + 3 would be used. (Author/publisher)
Samenvatting