Division: General - 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)

The following information constitutes the complete set of input data for sound propagation calculations with the methods to be used for noise mapping:

Emitted sound power level spectrum in octave bands
Working hours (day, evening, night, on a yearly averaged basis)
Location (coordinates x, y) and elevation (z) of the noise source
Type of source (point, line, area)
Dimensions and orientation
Operating conditions of the source
Directivity of the source.

The point, line and area source sound power are required to be defined as:

For a point source, sound power L_W and directivity as a function of the three orthogonal coordinates (x, y, z);
Two types of source lines can be defined:
source lines representing conveyor belts, pipe lines, etc., sound power per metre length L_W′ and directivity as a function of the two orthogonal coordinates to the axis of the source line,

source lines representing moving vehicles, each associated with sound power L_W and directivity as a function of the two orthogonal coordinates to the axis of the source line and sound power per metre L_W′ derived by means of the speed and number of vehicles travelling along this line during day, evening and night; The correction for the working hours, to be added to the source sound power to define the corrected sound power that is to be used for calculations over each time period, C_W in dB is calculated as follows:

C_{W} = - 10lg (\frac{l \times n}{1000 \times V \times T_{0}})

(2.4.1)

Where:

V

Speed of the vehicle [km/h];
Number of vehicles passages per period [-];
Total length of the source [m].
For an area source, sound power per square metre L_W/m2 , and no directivity (may be horizontal or vertical).

The working hours are an essential input for the calculation of noise levels. The working hours shall be given for the day, evening and night period and, if the propagation is using different meteorological classes defined during each of the day, night and evening periods, then a finer distribution of the working hours shall be given in sub-periods matching the distribution of meteorological classes. This information shall be based on a yearly average.

The correction for the working hours, to be added to the source sound power to define the corrected sound power that shall be used for calculations over each time period, C_W in dB is calculated as follows:

C_{W} = 10 \times \lg (\frac{T}{T_{ref}})

(2.4.2)

where

T is the active source time per period based on a yearly averaged situation, in hours;
T_ref is the reference period of time in hours (e.g. day is 12 hours, evening is 4 hours, night is 8 hours).

For the more dominant sources, the yearly average working hours correction shall be estimated at least within 0,5 dB tolerance in order to achieve an acceptable accuracy (this is equivalent to an uncertainty of less than 10 % in the definition of the active period of the source).

Division General