Author Topic: SiteNoise - How do I set the soft ground effect?  (Read 1834 times)

roger

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SiteNoise - How do I set the soft ground effect?
« on: June 06, 2016, 05:22:10 PM »
There are two parts to setting the soft ground effect.
The first is to set the Ground Type at the source.  When you enter the 'Fixed Working Properties' (or Route Segment Properties) then under Fixed Working Properties (or Route Parameters) there is a property called 'Ground Type'. This can be set to Hard Ground or Soft Ground.  If you choose Hard ground, soft ground attenuation will be omitted.  You must choose Soft Ground if you want NoiseMap to work out whether there is any soft ground effect.  [As an alternative, you can enter Hard and Soft Ground outlines, which allows variable ground cover to be used, see the User Manual.]

The second part is to select the methodology for calculating the soft ground attenuation.  Go to Parameters>Calculation Parameters and go down to BS5228 SiteNoise  Calculations. Under Soft Ground Correction, you have the options of BS5228:1997, Concawe and CRTN.  The differences are fully detailed in the User Manual, but at a distance of 1 km from the source, typically BS5228:1997 gives slightly less than CONCAWE (which is an oil and gas industry procedure) and a lot less than CRTN (although this may be because CRTN should not be used at long distances.)

Generally, the BS5228 procedure should be satisfactory.

Note that if the source is screened from the receiver, for example by the ground contours, and the screening is more than the soft ground attenuation, then the soft ground will appear to have no effect.

If you want to check the values of each of the corrections, such as hard ground, soft ground and barrier screening, then do a 'live' calculation with the 'one line per segment' option selected. To do this, you need to create a receiver point and then select Calculate>All Receivers from the menu.  This will provide each of the calculation corrections so you can see the effect they have on the end result.