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Some Basics and Terminology
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Let us first consider which types of development require protection from noise, which are considered noise tolerant, and the usual time periods in concern.
Here are some commonly used terms when we refer to noise criteria.
The term "Noise Sensitive Receiver", often abbreviated as NSR, refers to premises that is used for purposes sensitive to noise and requires protection. Examples of noise sensitive receivers are domestic premises, hotels and hostels, educational institutions and hospitals and clinics. Please click on the following diagram to see the enlarged photos.
Non-NSRs include multi-storey car parks and markets, godowns, community uses such as sports complexes and commercial centres or premises. Please click on the following diagram to see the enlarged photos.
A day is often divided into three time periods as indicated below :
The Type of Area Containing NSR refers to the characteristics of the area in which the NSR is located. The table below indicates the types and contains some typical examples. There is a mimic photo for each of the examples. Click on the mimic photo for enlarged viewing.
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Type
of Area Containing NSR
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Examples
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| (i) |
Rural
area, including country parks or village
type developments |
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| (ii) |
Low
density residential area consisting of
low-rise or isolated high-rise developments |
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| (iii) |
Urban
area |
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| (iv) |
Area
other than those above |
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The term "Influencing
Factors", abbreviated as IF, refers
to industrial areas, major roads or areas that are
situated within the boundary of the Hong Kong
International Airport. Their presence in the
vicinity of a NSR may dominate the ambient
or background noise there in such a way that
it is impractical to stipulate too low a noise
limit for either planning or control purpose.
The term "industrial area"
refers to an area which consists of a number
of factories or industrial establishments;
or an establishment which is having industrial
operation or operations of a significant scale.
A "major road" means a road
which has a heavy and generally continuous
flow of vehicular traffic and, in normal circumstances,
means a road with an annual average daily
traffic flow in excess of 30,000 vehicles. Where a
major road has an unusually low traffic flow
rate (less than 300 vehicles per hour) at
the time of day under consideration, it shall
not be considered as an IF at that time.
The term "Degree to which NSR is affected
by IF" refers to how the NSR is being
affected by the IF. It can be either :
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(a)
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not
affected, or
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(b) |
indirectly
affected, or
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(c) |
directly
affected.
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For "directly
affected", the NSR is at such a position
that noise generated by the IF is readily
noticeable at the NSR and is a dominant feature
of the noise climate of the NSR.
"Indirectly affected" means
that the NSR is at such a location that noise
generated by the IF, whilst noticeable
at the NSR, is not a dominant feature of the
noise climate of the NSR.
For "not affected", the NSR
is at such a location that noise generated
by the IF is not noticeable at the NSR.
The "Area Sensitivity Rating",
abbreviated as ASR, is a rating of
the area in which the NSR is located. The
ASR can be either A, B or C and is derived
from the following table after knowing the
Type of Area Containing NSR,
any presence of IF, and "Degree
to which NSR is affected by IF".
Please click on the demo button to read the
details.
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| Noise
Criteria for Control |
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Noise from
Percussive Piling
Percussive piling is not allowed during the Prohibited
Period. (The Prohibited Period is from 7:00 p.m.
to 7:00 a.m. on weekdays and any time on public
holidays including Sundays.)
A valid Construction Noise Permit(CNP) issued
by the Environmental Protection Department is
required for the carrying out of percussive piling
during the restricted hours, i.e. 7:00 a.m. to
7:00 p.m. on weekdays not being a public holiday.
Depending on the noise, a CNP holder may carry
out percussive piling for a total duration of
3 hours, 5 hours or 12 hours during the restricted
hours each day.
Table 1 of the Technical Memorandum on Noise
from Percussive Piling showing Acceptable
Noise Levels (ANLs) for various types
of NSR is reproduced as follows :
The ANLs shown
in the above table are to be reduced by 10 dB(A)
for NSRs such as hospitals, medical clinics,
educational institutions, courts of law or other
NSRs which are considered to be particularly
sensitive to noise. Any associated noise measurement shall be made in Leq(5 min).
For further details, please refer to the Technical
Memorandum on Noise from Percussive Piling by
clicking here.
For details of the legislative control on percussive
piling, please click here.
Noise from Construction Work other than
Percussive Piling
This type of work is also called general construction
work.
The term "Designated Areas",
abbreviated as DAs, is a special term
used in the control of noise from general construction
work. DAs are built up or populated areas. Because
DAs contain considerable number of NSRs, noise
affecting these areas warrants a tighter control.
Non designated areas are not built up areas
and may include commercial districts, industrial
zones and similar less noise sensitive uses.
The following map shows the distribution of
DAs in the territory:
Demarcation of DAs can be viewed on the EPD website. For accessing it, please click here:
Some general construction work employ powered mechanical equipment (PME), i.e. machines driven by electricity, compressed air or hydraulic means. In other situations; the construction work may involve hammering and erection or dismantling of formwork or scaffolding.
Within Designated Areas, powered mechanical equipment (PME) is categorized into Specified Powered Mechanical Equipment (SPME) and non-SPME. The SPME are generally noisier and warrant tighter control.
The following are SPME:
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Hand-held breaker |
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Bulldozer |
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Concrete
lorry mixer |
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Dump truck |
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Hand-held vibratory poker
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Within DAs, three types of general construction works are particularly noisy warrants tighter control. There are called Prescribed Construction Work (PCW):
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(a)
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Erection or dismantling of formwork or scaffolding
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(b) |
Loading, unloading or handling of rubble, wooden boards, steel bars, wood or scaffolding material
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(c) |
Hammering
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There are two
sets of noise criteria or Basic Noise Levels,
in dB(A), abbreviated as BNLs:
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(a)
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BNLs contained
in the Technical Memorandum on Noise from
Construction Work in Designated Areas
The above
table is used in the assessment of CNP
applications for construction work using
one or more of the SPME in construction
sites located within DAs.
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(b) |
BNLs contained
in the Technical Memorandum on Noise from
Construction Work other than Percussive
Piling
This table
is used in the assessment of CNP applications
for construction work using any PME in
construction sites located within Non-DAs;
and for construction work using PME
other than SPME in construction sites
located within DAs.
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The BNLs are
modified to take into account the duration
of the construction work and any CNPs hitherto
issued for the same sites to give a set of Acceptable
Noise Levels, abbreviated as ANLs. Any associated noise measurement shall be made in Leq(5 min).
Noise from the construction sites is then predicted
using standard acoustical principles. If the predicted
noise does not exceed the ANLs, CNP will be
issued. Otherwise, CNP will not be issued.
For further details, please refer to the Technical
Memorandum on Noise from Construction Work in
Designated Areas and the Technical
Memorandum on Noise from Construction Work other
than Percussive Piling.
For details of legislative control on general
construction works other than percussive piling,
please click here.
Noise from Constructing or Decommissioning of Designated Projects under the Environmental Impact Assessment Ordinance.
Apart from the above controls on construction activities under the Noise Control Ordinance, there are also noise criteria for carrying out daytime construction activities during the construction or decommissioning phase of designated projects under Environmental Impact Assessment Ordinance. These noise criteria shall be met as far as practicable. All practicable mitigation measures shall be exhausted and the residual impacts minimized.
Noise from Places other than Domestic
Premises, Public Places or Construction Sites
This kind of noise is commonly known as noise from industrial/commercial premises or simply industrial/commercial noise. Examples of sources of this type of noise are factories, restaurants, electric sub-stations and similar stationary noise sources.
This kind of noise is controlled under a system of Noise Abatement Notices. The noise under investigation is measured and corrected for any special intrusive characteristics such as tonality, impulsiveness and intermittency in accordance with the Technical Memorandum for the Assessment of Noise from Places other than Domestic Premises, Public Places or Construction Sites issued under the Noise Control Ordinance(NCO).
If the noise is found to exceed statutory limits,
a Noise Abatement Notice (NAN) will be issued
to the relevant party or parties requiring them
to abate the noise to within the statutory limits
within a given time period.
Table containing Acceptable Noise Levels
(ANLs) in dB(A) of the Technical Memorandum is reproduced
as follows :
The values in the above table apply to airborne noise. In case of noise transmitted primarily through the structural elements of a building or buildings, the appropriate ANL is 10 dB(A) less than the values shown in the table. This kind of noise is known as structural-borne noise. For examples, vibration from pumps and pipings may cause noise to be transmitted through the building structure.
The issue of ASR has been discussed in an earlier part of this Module. For a recap, please click here. The Technical Memorandum contains a special provision on ASR. The provision is as follows :
"Any NSR shall, irrespective of the above table, be assigned an ASR of C if it is within 100 m of a zone designated as Industrial or Industrial Estate on a statutory Outline Zoning Plan, or an ASR of B if it is between 100 m and 250 m from such a zone, except in cases where the above table indicates an ASR of C.
For further details, please refer to the Technical Memorandum by clicking here.
For details of legislative control on noise from places other than domestic premises, public places or construction site, please click here.
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| Noise Criteria for Planning |
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The basic role
of planning against noise is to provide an environment
whereby noise perceived at noise sensitive uses
satisfies the appropriate noise criteria.
The principle is to ensure that:
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(a)
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new
noise sensitive uses are located where they
will not be exposed to excessive noise levels;
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(b) |
new
noise emitters are located away from existing, committed or planned
sensitive uses; and
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(c) |
where
other constraints do not permit either of
the above, noise reduction designs should be incorporated into the noise
emitters at the earliest stage of planning. Where a completely acceptable
noise exposure cannot be obtained at the noise sensitive uses,
acoustic insulation should be provided.
For more details on mitigation measures,
please click here.
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Noise standards for planning purposes are set out under the Environmental Impact Assessment Ordinance Technical Memorandum (EIAO-TM).
The "Environmental Guidelines for Planning in Hong Kong", which form parts of the Hong Kong Planning Standards & Guidelines (HKPSG) published by the Planning Department, also provides guidelines on planning on most environmental issues.
For further details on the Hong Kong Planning Standards & Guidelines (HKPSG), please click here and you will be directed to the website of the Planning Department.
For more details on planning, please click here.
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