The aircraft noise impact assessment presented in the environmental impact assessment for the proposed expansion of Hong Kong International Airport into 3RS was undertaken based on the noise exposure forecast, an internationally accepted noise metric.
It also complies with the requirements set out in the Technical Memorandum on EIA Process and the EIA Study Brief.
NEF is a criterion that takes into account not only the peak noise level, but also the duration of fly-over, the tonal characteristics and the number of aircraft movements in the daytime and nighttime period. It also includes a parameter that weighs aircraft noise generated at night almost 17 times heavier than noise produced during the daytime, therefore acknowledging the more significant impact of aircraft noise at night compared to daytime. Such an approach provides a more holistic view on the potential impact of aircraft noise over a period of time.
Similar to Hong Kong, most international airports have adopted cumulative average noise energy metrics for planning. Hong Kong currently adopts NEF 25 as the aircraft noise standard, which is comparable to, or even more stringent than the standards adopted in many other places, such as Singapore, Canada and the United States.
We cannot and should not rely on the instantaneous maximum decibel levels of individual flights recorded at the existing aircraft noise monitoring stations as the indicator for airport planning assessment, since such an approach is considered inadequate and non-comprehensive.
As stated in the EIA report, all major