{
  "url": "https://openlegislation.uk/eu-directive-2015-996/annex/division-ASSESSMENT/division-2/division-2.5/division-2.5.6/division-4",
  "json_url": "https://openlegislation.uk/eu-directive-2015-996/annex/division-ASSESSMENT/division-2/division-2.5/division-2.5.6/division-4.json",
  "legislation": "eudr/2015/996",
  "legislation_title": "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)",
  "legislation_url": "https://openlegislation.uk/eu-directive-2015-996",
  "path": "annex/division/ASSESSMENT/division/2/division/2.5/division/2.5.6/division/4",
  "kind": "division",
  "number": null,
  "heading": "Acoustic characterisation of ground",
  "text": "The acoustic absorption properties of the ground are mainly linked to its porosity. Compact ground is generally reflective and porous ground is absorbent.\nFor operational calculation requirements, the acoustic absorption of a ground is represented by a dimensionless coefficient G, between 0 and 1. G is independent of the frequency. Table 2.5.a gives the G values for the ground outdoors. In general, the average of the coefficient G over a path takes values between 0 and 1.\nTable 2.5.a\nG values for different types of ground\nDescription\nType\n(kPa · s/m2)\nG value\nVery soft (snow or moss-like)\nA\n12,5\n1\nSoft forest floor (short, dense heather-like or thick moss)\nB\n31,5\n1\nUncompacted, loose ground (turf, grass, loose soil)\nC\n80\n1\nNormal uncompacted ground (forest floors, pasture field)\nD\n200\n1\nCompacted field and gravel (compacted lawns, park area)\nE\n500\n0,7\nCompacted dense ground (gravel road, car park)\nF\n2 000\n0,3\nHard surfaces (most normal asphalt, concrete)\nG\n20 000\n0\nVery hard and dense surfaces (dense asphalt, concrete, water)\nH\n200 000\n0\nGpath is defined as the fraction of absorbent ground present over the entire path covered.\nWhen the source and receiver are close-by so that dp ≤ 30(zs + zr ), the distinction between the type of ground located near the source and the type of ground located near the receiver is negligible. To take this comment into account, the ground factor Gpath is therefore ultimately corrected as follows:\nG′path =\nG path d p 30 z s + z r + G s 1 − d p 30 z s + z r\nif dp ≤ 30(zs + zr )\n(2.5.14)\nGpath\notherwise\nwhere Gs is the ground factor of the source area. Gs = 0 for road platforms, slab tracks. Gs = 1 for rail tracks on ballast. There is no general answer in the case of industrial sources and plants.\nG may be linked to the flow resistivity.\nFigure 2.5.b\nDetermination of the ground coefficient Gpath over a propagation path\nThe following two subsections on calculations in homogeneous and favourable conditions introduce the generic Ḡw and Ḡm notations for the absorption of the ground. Table 2.5.b gives the correspondence between these notations and the Gpath and G′path variables.\nTable 2.5.b\nCorrespondence between Ḡw and Ḡm and (Gpath , G′path )\nHomogeneous conditions\nFavourable conditions\nAground\nΔground(S,O)\nΔground(O,R)\nAg round\nΔground(S,O)\nΔground(O,R)\nḠw\nG′path\nGpath\nḠm\nG′path\nGpath\nG′path\nGpath",
  "extent": "E+W+S+N.I.",
  "status": null,
  "version": "current",
  "annotations": [
    {
      "type": "footnote",
      "label": "f1",
      "text": "The absorption of porous road pavements is taken into account in the emission model."
    }
  ],
  "outstanding_effects": [],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/eudr/2015/996/annex/division/ASSESSMENT/division/2/division/2.5/division/2.5.6/division/4",
    "retrieved_at": "2026-11-01T15:21:38.862218+00:00"
  },
  "licence": "Open Government Licence v3.0",
  "licence_url": "https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/",
  "attribution": "Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives."
}