Noise: Noise mapping
Noise Mapping England research project
A Research Study on Aircraft Noise Mapping at Heathrow Airport
To assist in the implementation of the Environmental Noise Directive (2002/49/EC) (END) and the development of a National Ambient Noise Strategy (NANS), this report was prepared by the Environmental Research and Consultancy Department of the Civil Aviation Authority.
Aircraft noise mapping has, effectively, already been undertaken for many years at some airports in the form of the production of aircraft noise contours. These contours usually relate to an average summer day and cover the 16 hour period between 0700 and 2300. At some airports, night contours are produced from time to time covering 2300-0700. The contours are presented in terms of the A-weighted equivalent continuous noise level (LAeq).
For the Environmental Noise Directive, aircraft noise mapping (or contours) have to be produced for an annual average day (rather than a summer average day), and have to be produced in terms of a new noise indicator (the Lden) and for an annual average night (2300-0700). The new indicator takes account of all aircraft movements throughout an average 24 hour period, but adds 'penalties' to the noise arising in the evening (+ 5 dB) and the night (+10 dB). Evening is defined as 1900-2300. The separate night contours show the noise exposure without any penalty.
This research study had two main aims:
1. to investigate various technical issues that arise as a result of moving from producing summer average LAeq contours to producing annual average Lden contours; and
2. to produce Lden and Lnight contours for Heathrow Airport for the year 2001.
The current production of contours makes certain assumptions. These include the following:
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the receiver height is 1.2m above ground; and
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the topography around the airport is flat and at runway level;
The study has examined re-standardizing on a 4m receiver height, and the effect of incorporating a limited representation of actual topography (modifying the slant distance, but not reflection or ground attenuation effects).
In addition, the contours currently tend to be based on the results for 100m by 100m grids. Other noise sources that may be mapped might be based on 10m by 10m grids, the higher resolution being necessary because of the much greater importance of surface-level shielding and reflection effects. The need to integrate air noise with road and rail noise for agglomeration mapping requires a common grid density. The study, therefore, also investigated what error might occur if 10m by 10m results were interpolated from the 100m by 100m results rather than calculating the 10m by 10m results directly.
It was recognised that the presence of Concorde in the fleet mix had a significant effect on the size and shape of the contours. The year 2001 was unusual in so far as Concorde only flew a restricted schedule towards the end of the year following its re-entry into service after modifications following the accident in 2000. Thus, in order to understand fully the influence of Concorde, several assumptions were tested. These were:
- 2001 contours assuming Concorde operated at its 1999 level of activity;
- 2001 contours assuming that Concorde flew as it did in that year; and
- 2001 contours excluding any Concorde movements.
Because Concorde has since been retired from service, these comparisons
are now largely of academic interest only.
The other variable that was examined was the modal split, i.e. the amount
of time the airport operated with aircraft taking off and landing towards
the west (westerlies) and vice versa (easterlies).
In addition to producing results for the Lden and Lnight, results have also been produced for the other constituent elements of Lden, namely Lday (the equivalent continuous level for the daytime period of 0700-1900) and Levening (the equivalent continuous level for the evening period of 1900-2300). Values for the area enclosed within various contour bands, together with the population and the number of households, have been produced.
When evaluating the results it must be remembered that the annual average Lden indicator is different from the summer average 16 hour LAeq indicator that has traditionally been used to describe the noise exposure from the airport. Thus the two sets of results must not be compared. Instead they should simply be seen as two methods of describing average noise exposure at the airport.
The full report is available to download
here as an Adobe Acrobat 
file (N.B. large file - 8.2 MB) 
Further information is available on our Help page
about downloading or reading Adobe Acrobat
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Contacting Defra
If you want further information that is not covered by these pages, you can contact us by e-mail at noise@defra.gsi.gov.uk
Page last modified:
14 May 2004
Page published: 10 March 2004