Road traffic can cause noise problems across long distances from roads. The role of meteorological conditions is getting more important with increasing distance from the road axes. Current computer models for computing street noise pollution ignore these influences largely. With currently available computing power, we can expect the significant increase in accuracy from theoretical studies about street noise.
The project will develop a calculation method for the determination of street noise pollution. Especially new approaches in the treatment of surface effects and meteorological influences will be examined. The calculation model will be provided as a prototype in the form of software and will be used for calculations in special situations.
In addition, a comparison with the known models will be carried out.
Based on an overview of computational methods for sound propagation considering weather effects a ray tracing algorithm (called SonRoad-M) was developed to account for curved propagation as a consequence of inhomogeneous atmosphere (due to wind speed and temperature gradients). The algorithm that is based on geometrical acoustics was enhanced by an empirical correction to account for sound propagation into shadow zones. The correction was calibrated with a numerical model based on wave theory (finite differences in the time domain).
SonRoad-M was successfully validated with own measurements and measurements reported in literature.
For different prototype situations and weather statistics the relevance of weather on sound propagation attenuations was investigated. From these findings simple rules-of-thumb can be derived to estimate the importance of weather effects. During daytime significant weather effects can be expected at distances above 50 to 100 m in cases without shielding (attenuation compared to neutral conditions). During the night and in case of shielding clear weather effects show up for distances above 100 m (amplification compared to neutral conditions).
Software for computation of street noise pollution taking into account surface effects and meteorological influences.