4                     NOISE




4.1               This Section presents an assessment of the potential noise impacts pertinent to the construction and operation phase of the Project, and recommends appropriate mitigation measures, where necessary. 


Environmental Legislation, Standards and Guidelines


4.2               The Noise Control Ordinance (NCO) and Environmental Impact Assessment Ordinance (EIAO) provide the statutory framework for noise control.  Assessment procedures and standards are set out in the five Technical Memoranda (TMs) listed below:

Ÿ             TM on Environmental Impact Assessment Process (EIAO-TM)

Ÿ             TM on Noise from Construction Work other than Percussive Piling (GW-TM)

Ÿ             TM on Noise from Percussive Piling (PP-TM)

Ÿ             TM on Noise form Construction Work in Designated Areas (DA-TM)

Ÿ             TM on Noise from Places other than Domestic Premises, Public Places or Construction Sites (IND-TM)


Construction Noise


4.3               Daytime construction noise (excluding percussive piling) between the hours 0700 – 1900 on weekdays, is controlled under the EIAO.  Annex 5 of the EIAO-TM sets out the construction noise limits, which are Leq(30 min) 75dB(A) for domestic premises and Leq(30 min) 70dB(A) for schools during normal hours (65dB(A) during examination periods) and all other places where unaided voice communication is required. 


4.4               Construction activities other than percussive piling using powered mechanical equipment (PME) undertaken at other times (i.e. during restricted hours) are under the control of the NCO.


Fixed Plant Noise


4.5               Operational noise emitted from the fixed noise source is controlled under the NCO and IND-TM.  According to the TM, the acceptable Noise Levels (ANLs) for different Area Sensitivity Ratings (ASRs) are given in Table 4.1.


4.6               The ANL is a function of the type of area within which the NSR is located, and the degree of the effect on the NSR of influencing factors such as major roads and industrial areas.  The ANLs for all ASRs are provided in Table 4.1.


Table 4.1          Acceptable Noise Levels (ANLs) (dB(A))


Time Period




Day (0700 to 1900 hours)




Evening (1900 to 2300 hours)

Night (2300 to 0700 hours)





4.7               The EIAO-TM states that all fixed noise sources should be so located and designed so that when assessed in accordance with the IND-TM, the level of the intruding noise at the facade of the nearest sensitive use should be at least 5 dB(A) below the appropriate ANL shown in Table 2 of the IND-TM or, in the case of the background being 5 dB(A) lower than the ANL, the predicted noise level should not exceed the background.


Description of Environment


4.8               The Project site is located in the North Wan Chai District, and is bounded by Convention Avenue, Expo Drive, Expo Drive Central and Expo Drive East. The surrounding landuses to the Project site are mainly a mixture of commercial buildings, government buildings and open spaces. To the south of the site is dominated by high-rise commercial buildings (e.g. Grand Hyatt Hotel, Renaissance Harbour View Hotel, Great Eagle Centre).


4.9               Major noise sources identified within this area include traffic noise from nearby road networks, e.g. Convention Avenue, Expo Drive East and Harbour Road. The ambient noise level is expected to be moderate to high.


Noise Sensitive Receivers


4.10            Representative Noise Sensitive Receivers (NSRs) were selected in accordance with the criteria in the EIAO-TM to evaluate the potential noise impacts. Table 4.2 summarises the selected NSRs for the noise impact assessment.  The locations of representative NSRs in the vicinity of the proposed work areas are illustrated in Figure 4.1.




Table 4.2          Representative Noise Sensitive Receivers




Land Use




Hong Kong Academy for Performing Arts

Government / Institution / Community


With A/C(3)


Causeway Centre





Renaissance Harbour View Hotel

Other Specified Uses


With A/C(3)


Grand Hyatt Hotel

Other Specified Uses


With A/C(3)


(1) Horizontal distance between NSR to the nearest project boundary

(2) NSR is located next to the Project Site

(3) With central ventilation system


4.11            As noted from site visits, the identified NSRs except NSR N2 are provided with central ventilation systems. As such, they do not rely upon opened windows for ventilation, and are therefore less noise sensitive. The noise criteria as stipulated in the EIAO-TM only apply to NSRs which rely on opened windows for ventilation. Thus, the EIAO-TM criteria would not be applicable to those NSRs with central ventilation systems (i.e. NSR N1, N3 and N4), and these NSRs will be excluded in this assessment.


4.12            As shown in Figure 4.1, the NSR N2 is located in urban area of Wan Chai with an annual average daily traffic flow in excess of 30,000 running through the nearby Gloucester Road. However, the ASR of the north facing façade (most affected façade) of NSR N2 would be “B” instead of “C” as the façade is not affected by the nearby influencing factor. Therefore, the planning criteria would be 60 dB(A) for daytime operations and 50 dB(A) for night-time operations.


Identification of Impacts


Construction Phase


4.13            The potential source of noise impact during the construction phase of the Project would be the use of PME for various construction activities as described in Section 2. As indicated in Table 2.1, the proposed Project will last from May 2006 to March 2009. The major construction activities for the Project which would be potential sources of construction noise in the Study Area include construction of temporary footbridge/working platform/superstructure for atrium link extension, demolition of existing atrium link, piling and foundation works. The construction noise impacts arising from the proposed project are discussed in Sections 4.17 to 4.20.

4.14            Generally, the construction activities of the Project would be carried out in non-restricted hours (0700-1900 hours) during normal working days. In case of any construction activities during restricted hours, it is the Contractor’s responsibility to ensure compliance with the NCO and the relevant TMs. The Contractor will be required to submit CNP application to the Noise Control Authority and abide by any conditions stated in the CNP, should one be issued.


4.15            Based on the preliminary design information, percussive pilling would be used for the driving of temporary marine piles into the seabed. Percussive piling is prohibited between 1900 and 0700 hours on any weekday not being a general holiday and at any time on Sunday or general holiday.  A CNP is required for carrying out of percussive piling between 0700 and 1900 hours on any day not being a general holiday. The Contactor will be responsible to apply to the EPD for a CNP under the NCO. When assessing a CNP application for carrying out percussive piling, the Noise Control Authority is guided by the PP-TM.


Operation Phase


4.16            To cope with the building service requirement, plant rooms will be constructed and located at the north-eastern corner of the ALE on Level 2 and Level 3 (Figure 4.2 refers). They will accommodate chiller plant, chiller pump and flushing tank which are considered to be the major sources of fixed plant noise. The Sound Power Level (SWL) of the chiller plant are typically in range of 100 to 109 dB(A) with reference to the Good Practices on Ventilation System on Noise Control. The noise Impact arising from the operation of the identified fixed plant will be assessed in Sections 4.21 to 4.23.


Prediction and Evaluation of Impacts


Construction Phase


4.17            The major construction activities for the Project which would be potential sources of construction noise in the Study Area include construction of temporary footbridge/working platform/superstructure for atrium link extension, demolition of existing atrium link, piling and foundation works. PME likely to be used include breaker, crane, lorry, excavator, air compressor, generator and pilling machines, etc for these major construction activities. With reference to the GW-TM, the SWL of PME is typically in range of 108 to 122 dB(A). For a conservation estimation, the maximum SWL of the construction activities throughout the construction period would be estimated to be about 127 dB(A) by assuming two sets of typical PMEs operated concurrently.


4.18            As shown in the Figure 4.1, the nearest NSR rely on openable window for ventilation is the Causeway Centre (NSR N2). The distance from the NSR N2 to the nearest boundary of the work site is about 250m.  Given the separation distance of 250m from the nearest NSR N2, the noise attenuation would be about 56 dB(A) according to the GW-TM.  In addition, Causeway Centre is substantially screened by two office buildings (i.e. Great Eagle Centre and Harbour Centre) in between. According to the GW-TM, a negative correction of 10 dB(A) can be applied to the predicted noise level if all the items of PME are totally screened by a substantial barrier.


4.19            Taking into account the noise reduction provided by the large separation distance and the screening from the nearby office buildings, the construction noise levels at NSR N2 would be about 64 dB(A) which would be well within the EIAO-TM daytime construction noise criteria of 75dB(A). Therefore, adverse construction noise impact on Causeway Centre would not be anticipated. Good site practices and weekly environmental audit will be implemented properly during construction of the Project to check on compliance with the assessment criteria.


4.20            The construction of Central Reclamation Phase III (CRIII) would likely coincide with the construction of the Project.  Nevertheless, the nearest worksites of the CRIII are located more than 700m away from the nearest NSRs. It is therefore anticipated that cumulative noise impact associated with the CRIII would be minor and would be unlikely to cause adverse cumulative construction noise impact with the Project.


Operation Phase


4.21            With reference to the SWL of the typical building service equipment, the dominant noise source would be mainly due to the operation of chiller plants. Based on preliminary design information provided by the Engineer, there would be five chiller plants to be operated. Assuming all chiller plants with SWL of 109 to be operated at the same time, the total SWL of the equipment in plant rooms was estimated to be 116 dB(A) as a conservative assumption. As all the building service equipment will be housed in building structure, a 10 dB(A) noise reduction of noise emitted from the sources due to transmission loss of wall can be achieved.


4.22            As shown in Figure 4.1, Causeway Centre is substantially screened by two office buildings (i.e. Great Eagle Centre and Harbour Centre) in between. The project site would be screened from the line-of-sight of NSRs by building or the structures. This allowed a reduction in the predicted noise level by 10 dB(A) in accordance with the GW-TM.  The predicted noise levels at NSR N2 would be about 43 dB(A) taking into account the separation distance and the above-mentioned noise reduction. This predicted noise levels would be conservative because a well-designed building can have more than 10 dB(A) noise reduction due to transmission loss of building walls.


4.23            Insurmountable noise impact associated with the fixed noise sources from the Project would not be envisaged having regard to the fact that the separation distance between the Project Site and the nearest NSR N2 would be large and the line of sight of the NSR to the Project Site would be limited.


Mitigation of Adverse Environmental Impacts


Construction Phase


4.24            Although adverse noise impact would not be expected during the construction phase of the Project, good site practices will be implemented by the Contractor to minimize noise emission. The site practices listed below should be followed during each phase of construction:

Ÿ             Only well-maintained plant should be operated on-site and plant should be serviced regularly during the construction program;

Ÿ             Silencers or mufflers on construction equipment should be utilized and should be properly maintained during the construction program;

Ÿ             Mobile plant, if any, should be sited as far from NSRs as possible;

Ÿ             Machines and plant (such as trucks) that may be in intermittent use should be shut down between work periods or should be throttled down to a minimum;

Ÿ             Plant known to emit noise strongly in one direction should, wherever possible, be orientated so that the noise is directed away from the nearby NSRs; and

Ÿ             Material stockpiles and other structures should be effectively utilised, wherever practicable, in screening noise from on-site construction activities.


Operation Phase


4.25            Although no adverse noise impact would be expected during the operation phase of the Project, it is recommended that the following noise reduction measures should be considered as far as practicable during detailed design:

Ÿ             Choose quieter plants such as those which have been effectively silenced. 

Ÿ             Include noise levels specification when ordering new plants.

Ÿ             Locate fixed plants away from any NSRs as far as practicable.

Ÿ             Locate fixed plants in plant rooms with thick walls or specially designed enclosure

Ÿ             Locate noisy machines in basement or a completely separate building

Ÿ             Develop and implement a regularly scheduled plant maintenance programme so that plants are properly operated and serviced in order to maintain controlled level of noise. The programme should be implemented by properly trained personnel.




Evaluation of Residual Impacts


4.26            No adverse residual impact would be envisaged.


Environmental Monitoring and Audit


Construction Phase


4.27            To ensure all the recommended mitigation measures to be fully implemented during the construction stage, environmental audit is recommended. Details of the EM&A requirements are provided in a stand-alone EM&A Manual.


Operational Phase


4.28            No operation noise monitoring for fixed plant would be considered necessary.




4.29            Noise arising from the construction activities for Atrium Link Extension and operation of the fixed plant would not have significant impact on the NSRs located in the vicinity of the work sites. The nearest NSR which rely on openable window for ventilation is Causeway Centre (NSR N2) and it will be separated from the Project site for 250m. In addition, Causeway Centre is substantially screened by two office buildings (i.e. Great Eagle Centre and Harbour Centre) in between. In view of the large horizontal separation and limited line of sight, adverse construction and operation noise impact would not be anticipated. To minimize noise emissions, good site practices and noise reduction measures are recommended during the design and construction stage of the Project.