On the improved point-to-point calculations for noise mapping in shielded urban areas

Noise mapping of urban areas according to standardized engineering calculation methods systematically results in an underestimation of noise levels at areas shielded from direct exposure to noise, such as inner yards. In these methods, road traffic lanes are represented by point sources and noise levels are computed utilizing point-to-point propagation paths. For a better prediction of noise levels in shielded urban areas, the attenuation terms describing these propagation paths are extended by terms including geometrical aspects of the urban environment both in the source and in the receiver area. In the present work, it has been studied to what extent these terms may be treated as being independent of the source-receiver distance. Also, the validity of treating the propagation path in a 2D plane rather than in 3D is investigated. Results obtained from a wave-based acoustic propagation model have been used for this assessment.