What are the ANEF, N contours & Operational Noise Levels?
Australian Noise Exposure Forecast, otherwise known as the ANEF. It is the current Australian standard for forecasting aircraft noise. The ANEF is a forecast of the cumulative noise effect of a full year of airport operations, including changes in weather patterns and airline schedules. The resulting ANEF is therefore a measure of the total noise exposure over a 12-month period divided by 365 to show an average annual day. The ANEF is a forecast showing the noise levels of the four runways that have been planned for the airport since 1990, despite only two runways being operational currently. This is so governments and community can see areas that may potentially be affected by noise in the future, for land use planning purposes.
ANEF contours are given values of 20, 25, 30, 35 and 40. The higher the contour value, the greater the noise. The Airports Act says that the ANEF contour 30 is a ‘significant’ noise level.
N contours. To supplement the ANEF and better describe aircraft noise levels, the Australian Government, through the Department of Infrastructure and Transport in consultation with industry and the community has developed the N contour system. The N contours measure the number of aircraft noise events per day – exceeding 70, 65 or 60 decibels. This will help the user to see what level of noise impact can be expected where they live into the future.
N60 = 100 or more events exceeding 60 decibels per day
N65 = 50 or more events exceeding 65 decibels per day
N70 = 20 or more events exceeding 70 decibels per day
Night contours = 6 or more events exceeding 60 decibels per day
Operational Noise Levels. These noise contours show us the current operational noise levels from the airport’s operation (based on historical data - ANEI) and potential operational noise levels with a third runway (based on forecast data - ANEC).