# Commission Directive (EU) 2015/996 of 19 May 2015 establishing common noise assessment methods according to Directive 2002/49/EC of the European Parliament and of the Council (Text with EEA relevance), Division: Calculations in homogeneous conditions

Extent: E+W+S+N.I.

The attenuation due to the ground effect in homogeneous conditions is calculated according to the following equations:
if Gpath ≠ 0
A ground,H = max − 10 × lg 4 k 2 d 2 p z 2 s − 2 C f k z s + C f k z 2 r − 2 C f k z r + C f k , A ground,H,min
(2.5.15)
where
fm is the nominal centre frequency of the frequency band considered, in Hz, c is the speed of the sound in the air, taken as equal to 340 m/s, and Cf is defined by:
C f = d p 1 + 3 wd p e − wd p 1 + wd p
(2.5.16)
where the values of w are given by the equation below:
(2.5.17)
Ḡw may be equal to either Gpath or G′path depending on whether the ground effect is calculated with or without diffraction, and according to the nature of the ground under the source (real source or diffracted). This is specified in the following subsections and summarised in Table 2.5.b.
(2.5.18)
is the lower bound of Aground,H .
For a path (Si,R) in homogeneous conditions without diffraction:
Ḡw = G′path
Ḡm = G′path
With diffraction, refer to the section on diffraction for the definitions of Ḡw and Ḡm .
if Gpath = 0: Aground,H = – 3 dB
The term – 3(1 – Ḡm ) takes into account the fact that when the source and the receiver are far apart, the first reflection source side is no longer on the platform but on natural land.

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Source: https://www.legislation.gov.uk/eudr/2015/996/annex/division/ASSESSMENT/division/2/division/2.5/division/2.5.6/division/5 (the official version)
Page: https://openlegislation.uk/eu-directive-2015-996/annex/division-ASSESSMENT/division-2/division-2.5/division-2.5.6/division-5
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.