Environmental Impact Assessment Ordinance

Technical Memorandum

Annex 13


1. General

1.1 The annex describes the commonly adopted approaches and methodologies for assessment of noise impacts arising from designated projects. The methodologies may vary from case to case, depending on the nature of noise issues and the latest development in methods and techniques.

2. Potential Noise Sources

2.1 The potential noise sources could be, but not limited to, the following:

  1. road traffic noise

  2. fixed noise sources (including, but not limited to, general industrial noise sources, concrete batching plants, pump houses, electricity sub-stations, gas pressure reduction plants, rock crushing plants, quarries, railway depots/marshalling yards, airport facilities, wholesale markets, bus depots/termini, open car/lorry parks, vehicle pounding areas, refuse handling areas, abattoirs, container terminals, sand depots, public cargo working areas, multi-purpose terminals, fire stations, ambulance depots, tram depots)

  3. construction noise (including noise from powered mechanical equipment and vehicle movement on haul roads)

  4. rail noise

  5. aircraft noise

  6. helicopter noise

3. Noise Sensitive Receivers

3.1 The potential noise sensitive receivers could be, but not limited to, the following:

  1. Residential Uses
    • all domestic premises including temporary housing

  2. Institutional Uses
    • educational institutions including kindergarten and nurseries
    • hospitals
    • medical clinics
    • homes for the aged
    • convalescent homes
    • places of public worship
    • libraries
    • courts of law
    • performing arts centres
    • auditoria
    • amphitheatres

  3. Others
    • hostels
    • country parks

4. Noise Tolerant Uses

4.1 The potential noise tolerant uses could be, but not limited to, the following:

  1. multi-storey carparks
  2. multi-storey markets
  3. offices (with acoustic insulation)
  4. godowns
  5. community uses (eg. sports complexes, community centres), or
  6. commercial centres/premises

5. Assessment Methodology

Road Traffic Noise

5.1 The commonly accepted method in Hong Kong for the assessment of road traffic noise is based on the procedures given in the UK Department of Transport document "The Calculation of Road Traffic Noise". The road traffic noise is presented in terms of noise levels exceeded for 10% of the one-hour period for the hour having the peak traffic flow [L10(1h) dB(A)]. Predictions shall normally be based on the design traffic conditions or the maximum traffic projections within 15 years upon operation of the roadworks or occupation of the noise sensitive receivers or uses, whichever appropriate, and shall take into consideration future (both committed and planned) as well as existing roadworks and land uses.

Fixed Noise Sources

5.2 The assessment shall be based on standard acoustic principles. For assessment point and correction of tonality, impulsiveness and intermittency, reference shall be made to the Technical Memorandum on Noise from places other than Domestic Premises, Public Places or Construction Sites, issued under the Noise Control Ordinance. The noise levels shall be calculated using assumed plant inventories and utilisation schedule.

Construction Noise

5.3 The assessment shall be based on standard acoustic principles. In case the proponent or consultant would like to assess whether a Construction Noise Permit (CNP) could be issued or not in the context of programming construction works, reference should be made to the relevant technical memoranda issued under the Noise Control Ordinance (NCO): the Technical Memorandum on Noise from Percussive Piling, the Technical Memorandum on Noise from Construction Work other than Percussive Piling, and the Technical Memorandum on Noise from Construction Work in Designated Areas. Where no sound power levels can be found in the Technical Memoranda, reference shall be made to BS 5228 Part I or noise emission levels measured in previous projects in Hong Kong.

However, whether the Noise Control Authority would issue a CNP would depend on the application submitted according to the procedures laid down in the relevant technical memoranda issued under the NCO rather than this assessment exercise.

Noise from Vehicle Movement on Haul Roads

5.4 The assessment of noise from the movement of vehicles on-site shall be based on the methodology recommended in the British Standard BS 5228 Part I, Noise Control on Construction and Open Site, 1984.

Rail Noise

5.5 The assessment methodology shall be agreed with the Director of Environmental Protection prior to the commencement of the assessment.

Other Technical Memoranda under the Noise Control Ordinance (NCO)

5.6 The assessment of noise shall be made reference to any other relevant technical memoranda under the NCO that are in force at the time of assessment.

6. Consideration of Mitigation Measures

6.1 Where the predicted noise impacts exceed the applicable noise criteria, direct mitigation measures as shown below shall be considered and evaluated in an appropriate manner :

  1. alternative land use arrangement
  2. alternative siting
  3. screening by noise tolerant buildings
  4. setback of buildings
  5. decking over
  6. extended podium
  7. building orientation
  8. treatment of source
  9. alternative alignment
  10. noise barrier/enclosure
  11. special building design
  12. architectural features/balcony
  13. open-textured road surfacing

6.2 Upon exhaust of direct mitigation measures, indirect mitigation measures in the form of window insulation and air-conditioning is often the "last resort" in an attempt to abate the residual impact from noise sources not controlled under the Noise Control Ordinance, such as aircraft, road traffic and helicopter, because it will practically deprive the receivers of outdoor activities and an "open-window" life style. If a compromise is necessary when there are overriding constraints on the location and design of a development, which prevent full compliance with the appropriate noise standards laid down in Annex 5, an attempt shall be made to maximize the proportion of receivers protected, using noise mitigation measures at sources or building layout designs of the development. The remaining unprotected receivers shall be insulated using the suitable window types described in Table 2 of Annex 5. The acoustic insulation shall also require the provision of air-conditioning systems because of the warm and humid climate in Hong Kong.

6.3 If additional mitigation measures are required on the planned land uses even after adoption of all practicable direct measures on the roads, the practicality of these additional mitigation measures shall be evaluated and confirmed.