Abatement
Abatement is one of the means to resolve existing noise problems. Examples of these problems are :
- busy highways running through residential districts; and
- schools affected by noise from aircraft or road traffic.
The Government has implemented noise abatement programmes such as the School Insulation Programme, the Quiet Road Surfacing Programme and the Retrofit Noise Barrier Programme to reduce impact of traffic noise on existing noise sensitive receivers.
The Quiet Road Surface Programme
Road resurfacing may help redressing road traffic noise.
The use of brushed concrete as a road surface can contribute significantly to urban road noise levels due to the interaction of tyres with this rather rough surface.
To redress the impact of traffic noise on residents living close to high speed roads of brushed concrete surface, a 300-metre section of the Island Eastern Corridor was in 1987 resurfaced with an open-textured material, which is a type of bitumen for testing its noise reduction and engineering performance. The material was found to perform satisfactorily and provided a noise reduction of up to 5 dB(A) in the two-year trial period.
With such a promising result, the Government in 1989 started the Quiet Road Surface Programme. In this programme, suitable road sections are re-surfaced with an open-textured materials which help to reduce traffic noise. Please click on the demo button to see the details.
[Animation of highway surfaced with noise absorptive materials]
The programme for resurfacing suitable high speed roads with noise absorptive material was completed in 1999. A total of 11 kilometres of roads were resurfaced, providing noise relief to some 15,650 dwellings, as indicated by this chart. Please click on the demo button to see the details.
[Chart of relevant statistics for the Quiet Road Surface Programme]
This kind of low noise surface material is now a standard for all new high speed roads. In November 2000, the Executive Council endorsed a new policy to address the noise impacts from existing roads. One of the strands of this new policy is to re-surface suitable local roads with an open-textured materials. 72 local roads have been identified as suitable for resurfacing. Some 40,000 flats will benefit once all 72 roads are re-surfaced.
Selection criteria for roads to be resurfaced include:
- The road should be relatively level (otherwise engine noise will dominate);
- The road should originally be paved with brushed concrete or other similar non-open textured surfaced (producing a high level of road/tyre noise);
- The road must carry smooth high speed traffic (where road/tyre noise will be a problem) with a low percentage of heavy vehicles; and
- The traffic noise from the road is a dominant noise source (reducing which will become tangible).
For more details on how low noise surface material works please click here.
The School Insulation Programme
A large number of schools in Hong Kong have been badly affected by noise from road traffic, and from aircraft noise when the Kai Tak airport was still in operation. A School Insulation Programme to redress the noise problem for a quieter learning environment for students was implementd in 1987, under which improved windows including good quality glazing and air-conditioning were provided to the affected classrooms. Please click on the demo button to see the details.
[Animation of the School Insulation Programme]
Stage 1 of the programme, which lasted from April 1987 to April 1990, was to insulate classrooms against aircraft noise from the Kai Tak airport. Stage 2 (from April 1989 to March 1993) and Stage 3 (from April 1993 to March 1996) were to insulate classrooms against road traffic noise. The last stage, Stage 4, which ended in 1999, was to insulate the remaining schools against road traffic and railway noise.
This chart illustrates the results of the School Insulation Programme. Please click on the demo button to see the details.
[Chart of accumulated number of classrooms insulated over the years]
Retrofit Noise Barrier Programme
The Government announced in November 2000 a new policy to mitigate traffic noise impact of existing excessive noisy roads by way of installing noise barriers where practicable. Some 30 road sections with traffic noise exceeding 70 dB(A) were identified as technically feasible for retrofitting noise barrier. It is estimated that with these noise barrier in place, over 25,000 flats will have noise levels lowered by 1 to 19 decibels; and 70% residents along the concerned roads will have noise lowered to below the 70 dB(A) planning standard.