3... Noise impact Assessment.. 3-1

Introduction.. 3-1

Environmental Legislation, & Standards.. 3-1

Description of Environment.. 3-3

Assessment Methodology.. 3-6

Identification of Environmental Impacts.. 3-7

Evaluation of Impacts.. 3-9

Mitigation of Adverse Environmental Impacts.. 3-12

Construction Works During Restricted Hours.. 3-18

Residual Environmental Impacts.. 3-20

Environmental Monitoring and Audit Requirements.. 3-20

 

 

Table 3.1   EIAO-TM Daytime Construction Noise Standards

Table 3.2   Acceptable Noise Levels (ANL, Leq, 5min dB(A))

Table 3.3   Road Traffic Noise Planning Criteria

Table 3.4   Representative Noise Sensitive Receivers

Table 3.5   A Summary of Cumulative Construction Noise Impacts (Without Mitigation)

Table 3.6   Predicted Road Traffic Noise Levels in 2022 (Without Mitigation)

Table 3.7   Sound Power Levels for Specific Quiet PME

Table 3.8   A Summary of Cumulative Construction Noise Impacts (Mitigated – Use of Quiet PME)

Table 3.9   A Summary of Cumulative Construction Noise Impacts (Mitigated – Use of Quiet PME and Movable Noise Barriers)

Table 3.10   Predicted Road Traffic Noise Levels in 2022 (With Mitigation)

Table 3.11   Area Sensitivity Ratings for NSRs Selected for the Indicative Assessment

 

 

Figure 3.1   San Tin – Outline Zoning Plan

Figure 3.2a   Noise Sensitive Receivers within 300m from the Project Boundary

Figure 3.2b   Locations of Representative Noise Sensitive Receivers

Figure 3.3   Construction Work Areas

Figure 3.4   Locations of Noise Barriers Proposed in Other Project

Figure 3.5   Locations of Proposed Movable Noise Barriers

Figure 3.6   Locations of Proposed Noise Barriers

Figure 3.7   Typical Cross-Section of Proposed Noise Barriers

Figure 3.8   Plan of Movable Barrier for Segment Carrier

 

 

Appendix 3.1   Extent of Defined New Road

Appendix 3.2   Prevailing Road Traffic Noise Levels

Appendix 3.3   Powered Mechanical Equipment for Various Construction Activities (Unmitigated)

Appendix 3.4   Endorsement Letter from Transport Department

Appendix 3.5   Sample Computer Outputs of Road Traffic Noise Calculations

Appendix 3.6   Predicated Construction Noise Levels (Unmitigated)

Appendix 3.7   Assessment for Cumulative Construction Noise Impact from Concurrent Projects

Appendix 3.8   Road Traffic Noise Assessment Results`

Appendix 3.9   Powered Mechanical Equipment for Various Construction Activities (Mitigated-Use of Quiet Equipment)

Appendix 3.10   Predicted Construction Noise Levels (Mitigated-Use of Quiet PME)

Appendix 3.11   Powered Mechanical Equipment for Various Construction Activities (Mitigated-Use of Quiet Equipment and Movable Noise Barriers)

Appendix 3.12   Predicted Construction Noise Levels (Mitigated-Use of Quiet Equipment and Movable Noise Barriers

Appendix 3.13   Assessment for Construction Noise Impact During Restricted Hours

Appendix 3.14   Assessment of Noise Sensitive Receivers Eligible for Indirect Technical Remedies


3.                  Noise impact Assessment

 

Introduction

 

3.1              This section presents an assessment of potential noise impacts associated with the construction and operation of the proposed improvements to San Tin Interchange.  The objectives of the assessment are to identify and evaluate the potential noise impacts and recommend appropriate and practical mitigation measures to alleviate any identified noise impacts.

 

3.2              The noise assessment has been undertaken in accordance with the criteria and guidelines given in Annexes 5 and 13 of the EIAO-TM and the requirements specified under the EIA Study Brief.

 

Environmental Legislation & Standards

 

3.3              The principal legislation on the control of noise is the Noise Control Ordinance (Cap. 400) (NCO) and the Environmental Impact Assessment Ordinance (Cap. 499) (EIAO).  Five Technical Memoranda (TMs) issued under the NCO and EIAO for noise control approaches and criteria are listed below. 

 

·        Technical Memorandum on Noise from Places other than Domestic Premises, Public Places or Construction Sites (IND-TM);

·        Technical Memorandum on Noise from Construction Work in Designated Areas (DA-TM);

·        Technical Memorandum on Noise from Construction Work other than Percussive Piling (GW-TM);

·        Technical Memorandum on Noise from Percussive Piling (PP-TM); and

·        Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM).

 

Construction Noise

 

3.4              Under the EIAO, noise generated by general construction works during normal working hours (i.e. 0700 to 1900 hours on any day not being a Sunday or public holiday) at 1 m from the external façade of the uses, which rely on opened windows for ventilation is guided by the EIAO-TM.  The EIAO-TM noise standards are presented in Table 3.1.

 

Table 3.1       EIAO-TM Daytime Construction Noise Standards

 

Uses

Noise Standard (Leq, 30 min dB(A))

Domestic Premises

75

Educational Institutions (normal periods)

70

Educational Institutions (during examination periods)

65

 

3.5              The NCO provides statutory controls on general construction works during the restricted hours (i.e. 1900 to 0700 hours Monday to Saturday and at any time on Sundays and public holidays).  The use of powered mechanical equipment (PME) for carrying out of construction works during the restricted hours will require a CNP.  The Noise Control Authority is guided by the GW-TM when assessing such an application.  A CNP may be issued if the CNL is equal to or less than the ANL.  The ANLs are related to the noise sensitivity of the area in question and the Noise Control Authority will judge these at the time of the CNP application.  As conditions may vary between the time of the EIA for a project and the time of a CNP application, the assignment of any Area Sensitivity Ratings in the EIA is not binding upon the Noise Control Authority.  The relevant ANLs are shown Table 3.2, which are determined by Area Sensitive Ratings (ASRs).

 

Table 3.2         Acceptable Noise Levels (ANL, Leq, 5min dB(A))

 

Time Period

Area Sensitivity Rating

A

B

C

All days during the evening (1900-2300 hours) and general holidays (including Sundays) during the day and evening (0700-2300 hours)

60

65

70

All days during the night-time (2300-0700 hours)

45

50

55

 

Factors such as ASRs, ANLs, etc could affect the assessment results of a CNP application.  The Noise Control Authority would decide these at the time of assessment of such an application based on the contemporary situations/conditions.  It should be noted that the situations/conditions around the sites might change from time to time.

 

Operational Traffic Noise

 

3.6              The EIAO-TM provides guidance on acceptable road traffic noise levels at 1 m from the external façade of the uses which rely on opened windows for ventilation.  The relevant criteria are shown in Table 3.3.

 

Table 3.3         Road Traffic Noise Planning Criteria

 

Uses

Road Traffic Noise, L10 (1hr) dB(A)

Domestic premises, hotel, hostels, and offices

70

Educational Institutions

65

Hospital and clinics

55

Place of public worship and courts of law

65

Note: The criteria presented in the above apply to noise sensitive uses which rely on opened window for ventilation.

 

3.7              In case where predicted road traffic noise impacts exceed the relevant criteria, direct mitigation measures will be pursued as a first priority and recommended wherever practicable in order to reduce the noise impacts to within the acceptable level.  In accordance with Section 6.2 in Annex 13 of the EIAO-TM, if all practicable direct mitigation measures are exhaustedly employed, indirect technical remedies (ITR) in the form of window insulation and air-conditioning should be considered as the “last resort” to abate the residual impact at existing sensitive uses.  The location and numbers of the existing uses that may qualify for ITR under the ExCo directive “Equitable Redress for Persons Exposed to Increased Noise Resulting from the Use of New Roads” will have to be identified.  For the purpose of determining the eligibility of the affected existing premises for ITR, reference will have to be made to the following three criteria which were derived from CRTN and commonly adopted in other EIA projects:

 

1)      The predicted overall noise level from the new road, together with other traffic noise in the vicinity must be above 70 dB(A) for residential dwellings, 65 dB(A) for education institutions and place of public worship, all in L10(1hr).

 

2)      The predicted overall noise level is at least 1.0 dB(A) more than the prevailing traffic noise level, i.e. the total traffic noise level existing before the works to construct the road were commenced.

 

3)      The contribution to the increase in the predicted overall noise level from the new road must be at least 1.0 dB(A).

 

3.8              For the purpose of noise impact assessment, a ‘new’ road is defined when road section undergoes major modification which will directly result in 25% increase in lanes or substantial changes in alignment or characters (e.g. change to high speed road) of the existing road according to the Study Brief.  As a result, the proposed slip roads (including Slip Roads A, B, C, D, E and F) and the section of Castle Peak Road to be widened were defined as new roads.  Other roads including San Tin Highway, Fanling Highway, San Sham Road, Castle Peak Road, etc, that will remain either completely unchanged or will undergo only minor alternation were defined as ‘existing’ roads.  Appendix 3.1 illustrates the extent of the defined new roads and existing roads.

 

Description of Environment

Baseline Conditions

 

3.9              The Assessment Area is generally rural in nature, with the surrounding land comprising scattered village houses, school, temple, agricultural activities, and open storage.  In accordance with the San Tin Outline Zoning Plan (OZP) No.S/YL-ST/5, the land uses to the surrounding areas of the Project were zoned as green belt (GB), other specified uses (Comprehensive Development and Wetland Enhancement Area) (OU(CDWEA)), conservation area (CA), village type development (V), government/institution/community (GIC) and undetermined (U) (Figure 3.1). 

 

3.10          Based on site surveys, the environment of areas far away from the existing road network were generally quiet, whereas areas in the vicinity of the existing road network experienced high road traffic noise impact.  The existing traffic noise sources are mainly from San Tin and Fanling Highways, San Sham Road and Castle Peak Road.  The prevailing road traffic noise levels at existing noise sensitive receivers (NSRs) are in the range of 61 to 83 dB(A), exceeding the EIAO-TM noise criteria (Appendix 3.2).  With the proposed slip roads, the noise levels at these NSRs would likely be higher, if unmitigated.


Noise Sensitive Receivers

 

Existing Noise Sensitive Receivers

 

3.11          The existing NSRs within the Assessment Area include village houses such as those located at Tung Chan Wai, Wing Ping Tsuen, Tai Fu Tai, and along San Tin and Fanling Highways, school and temple.  These NSRs would likely be affected by noise associated with the construction works and operation of the Project. 

 

Future Noise Sensitive Uses

 

3.12          According to the San Tin OZP, the area to the southwest of the proposed slip roads was zoned as ‘V’ and the area to the northwest was zoned as ‘OU(CDWEA)’.  Based on the information provided by the Planning Department (PlanD), a planned residential development may be located within the OU(CDWEA) zone. 

 

3.13          In accordance with the EIA Study Brief, noise sensitive areas located within 300m from the project boundary have been identified (Figure 3.2a).  A number of representative NSRs, which would be the closest to the proposed road works, have been designated to represent the worst-case scenario.  Since no details of the possible future/planned NSRs within the ‘V’ and ‘OU(CDWEA)’ zones were available, seven assessment points were assigned within these zones for the purpose of the assessment.  The representative NSRs are tabulated in Table 3.4 and illustrated in Figure 3.2b.

 

Table 3.4         Representative Noise Sensitive Receivers

 

NSR ID

Location

Use

No. of Floors

Ground Elevation (mPD)

No. of Dwellings/ Classrooms Represented

Nearest Distance from Project Boundary (m)

V02

Village house near San Tin Highway

Residential

2

14

3

225

V03

Village house near San Tin Highway

Residential

1

10.9

1

180

V04

Village house near San Tin Highway

Residential

1

11.4

6

135

V05

Village house near San Tin Highway

Residential

2

5.9

2

20

V06*

Village house near San Tin Highway

Residential

2

5.9

2

10

V07

Village house near Tai Fu Tai

Residential

2 (1) 

6.1

6

75

V08

Village house near Tai Fu Tai

Residential

2 (1)

6.2

4

110

V09

Village house near Tai Fu Tai

Residential

1

6.2

1

115

V10*

Village house at Wing Ping Tsuen

Residential

3

3.9

3

150

V11

Village house at Wing Ping Tsuen

Residential

3

3.9

6

160

V12

Village house at Wing Ping Tsuen

Residential

3

3.1

12

245

V13

Village house at Tung Chan Wai

Residential

3

3.1

12

260

V14

Village house at Tung Chan Wai

Residential

2

2.9

5

285

V15

Village house at Tung Chan Wai

Residential

4

2.0

10

300

V16

Village house near San Tin Highway

Residential

1

9.5

1

140

V17

Village house near Ka Lung Road

Residential

3

11.8

3

105

V18*

Village house near San Tin Highway

Residential

1

6.5

1

30

V19*

Village house near San Tin Highway

Residential

2

5.1

2

40

V20*

Village house near Kwu Tung Road

Residential

1

4.0

2

45

V22*

Village house near Kwu Tung Road

Residential

2

8.6

3

35

V23*

Village house near Kwu Tung Road

Residential

1

8.6

3

95

V24

Village house near Kwu Tung Road

Residential

3

14.0

3

100

V25

Village house near Kwu Tung Road

Residential

2

10.4

2

70

V26

Village house near Kwu Tung Road

Residential

2

18.0

2

50

V27

Village house near Castle Peak Road

Residential

2

7.7

2

55

V28*

Village house near Castle Peak Road

Residential

2

6.4

4

75

V29

Village house near Lok Ma Chau Road

Residential

3

3.5

3

270

V30*

Village house near Lok Ma Chau Road

Residential

1

5.3

1

105

Sch1*

Tun Yu School

Educational Institution

1

8.7

9

120

T01

Temple near Tun Yu School

Place of worship

1

6.1

1

105

P01, P03

Assessment point for the ‘V’ Zone

Residential

3

3.9

--

5

P02

Assessment point for the ‘V’ Zone

Residential

3

3.9

--

10

P04 – P07

Assessment point for the ‘OU(CDWEA)’ Zone

Residential

206

5.6

--

5

Note: *        Selected for construction noise assessment.

(1)       Ground floor is retail.


Assessment Methodology

Construction Phase

 

3.14          Construction noise impact arising from the construction activities of the Project was assessed using the standard acoustic principles and the methodology outlined in the GW-TM issued under the NCO as well as the guideline given in Annex 13 of the EIAO-TM. 

 

3.15          Prior to the appointment of the Contractor, exact number and type of construction plant to be adopted for the construction activities are not known.  For the purpose of the construction noise assessment, a preliminary equipment inventory has been assumed based on typical construction activities of similar projects.  It was confirmed with the client that the assumed plant inventory would be reasonable and practicable for the completion of the Project within the scheduled construction programme.  Appendix 3.3 gives the assumed equipment inventory for various construction activities of the Project.  It is noted that the equipment inventories for both unmitigated and mitigated scenarios of various construction activities have been confirmed with the Project Proponent as being practicable in completing the works within the scheduled timeframe.

 

3.16          Sound power levels (SWLs) of the powered mechanical equipment (PME) in Appendix 3.3 were taken from Table 3 of the GW-TM.  Where no SWLs was given in the GW-TM, reference was made to the British Standard BS 5228:Part 1:1997 Noise and Vibration Control on Construction and Open Sites or noise emission levels measured in previous projects in Hong Kong. 

 

3.17          In order to give a more realistic calculation, reasonable percentage ‘on-time’ of each PME (the time when the PME is in operation within a 30 minutes time slot) opined by the engineer and confirmed with the client were assumed (Appendix 3.3). 

 

3.18          All PME items required for a particular construction activity were assumed to be located at a notional or probable source position of the segment where such activity would be undertaken.  Figure 3.3 shows the locations of work areas where various construction activities would be undertaken.  A +3 dB(A) façade correction has been added to the predicted noise levels in order to account for the façade effect at each representative NSR.  Practicable direct mitigation measures were recommended if exceedance of relevant criteria was predicted.  In case where the mitigated noise levels still exceed the criteria, the duration of the noise exceedance will be given.

 

Operational Phase

 

3.19          Potential road traffic noise impacts were predicted using our accepted in-house noise model which adopts the methodology in the UK Department of Transport’s Calculation of Road Traffic Noise (CRTN) (1988).  The road traffic noise was presented in terms of noise levels exceeded for 10% of the one-hour period for the hour having the peak traffic flow [L10(1hr) dB(A)].

 

3.20          According to the EIAO-TM, calculations of future road traffic noise were based on the maximum traffic forecast within 15 years period upon the commencement of the proposed roadwork in operation.  Afternoon peak hour traffic flow in year 2022 (Section 2) was considered to be the maximum traffic forecast during the period of 2007 to 2022 and hence adopted for the assessment.   

 

3.21          Prevailing road traffic noise were calculated based on the traffic forecast for the commencement year of the construction (i.e. 2005) in order to determine whether or not existing NSRs exposed to residual traffic noise impacts qualify for Indirect Technical Remedies (ITR) under this Project.

 

3.22          The proposed speed limit for the proposed slip roads was assumed to be 50 km/h.  The noise model adopted 100 km/hr traffic speed limits for the existing San Tin Highway and Fanling Highway and 50 km/hr for all other existing roads, such as Castle Peak Road, San Sham Road, etc.  Low noise road surfacing was assumed to be a standard feature for San Tin Highway and Fanling Highway in the assessment. 

 

3.23          The proposed Bridge A would be used for maintenance and emergency purpose.  Only very low traffic flow along the bridge is expectedand hence it was not included in the traffic noise assessment.  For the elevated sections of the proposed slip roads, it is confirmed that standard highway 0.8 m high solid parapet will be constructed along the road edges. 

 

3.24          Based on the Final Environmental Study Report of Expansion of Kiosks and Other Facilities at Lok Ma Chau Boundary Crossing, there are a 2m and a 2.5 m high plain barrier erected along the road edge of the northbound and southbound carriageway of the San Sham Road, respectively.  These noise barriers have been included in the noise model and their locations are shown in Figure 3.4. 

 

3.25          In view of the elevated nature of the Spur Line viaduct and the low-rise nature of the NSRs within the Assessment Area, the screening effect associated with the Spur Line viaduct is considered negligible and hence were not included in the noise model.  Since no details of the Northern Rail Link were available during this EIA study, the screening effect of the Northern Rail Links was also not taken into account.

 

 

Identification of Environmental Impacts

Construction Phase

 

3.26          Noise arising from the construction activities of the Project would likely have potential adverse noise impact on the nearby NSRs if unmitigated.  According to the preliminary construction programme (Figure 2.8), the major construction activities would start from April 2005 to March 2007 and include:

 

1)              Site clearance

2)              Site formation

3)              Construct retaining walls/slopes 

4)              Construct bored piles

5)              Cast pilecaps and piers

6)              Construct abutments

7)              Construct slip roads

8)              Widening of Castle Peak Road

9)              Erect segments by launching girder/mobile cranes

10)          Erect segments of on falsework for side spans

11)          Cast concrete parapets and install movement joints

12)          Road pavement and road marking

 

3.27          It is anticipated that percussive piling would not be required.  Generally, the above works would be carried out in non-restricted hours (0700-1900) with the exception of night-time work for the erection of precast concrete viaduct segments crossing/encroaching into existing San Tin Highway (Figure 3.3). 

 

3.28          For construction works planned during the restricted hours, it will be the responsibility of the Contractor to ensure compliance with the NCO and the relevant TMs.  In such cases, 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.  Therefore, the potential noise impacts of the night-time work were not formally assessed in this EIA study.  In order to facilitate the efforts of the project proponent to avoid any potential adverse noise impacts and evaluate whether the construction works in restricted hours are feasible or not in the context of programming construction work, an indicative assessment for construction noise during restricted hours was undertaken (Sections 3.59 – 3.65).  Regardless of the results of the assessment, the Noise Control Authority will process the CNP application, if necessary, based on the NCO, the relevant TMs issued under the NCO, and the contemporary conditions/situations.  Nothing in this report shall bind EPD in making its decision.  If a permit is to be issued, EPD will include any conditions considered appropriate and such conditions are to be followed while the works covered by the permit are being carried out.  Failure to comply with the conditions stipulated will lead to cancellation of the permit and prosecution action under the NCO.

 

3.29          As indicated in Section 2, construction of the Project would likely interface with the following projects:

 

Project

Anticipated Construction Programme

East Rail Extension – Sheung Shui to Lok Ma Cha Spur Line (KCRC Spur Line)

December 2002 to September 2006

San Tin Eastern Main Drainage Channel (EMDC)

October 2002 to June 2006

Drainage Channels in Northern New Territories – NTM04

October 2005 to October 2009

 

3.30          As indicated above, the construction of KCRC Spur Line, San Tin EMDC and NTM04 would likely coincide with the construction of the Project.  Based on the KCRC Spur Line EIA[1], the construction of the Spur Line was divided into different stages.  Major works of the section of the Spur Line falling within the Assessment Area would be completed before 2005 and hence adverse cumulative noise impact from the construction works of the Spur Line would not be anticipated. 

 

3.31          Concurrent noise impacts from the San Tin EMDC works would likely occur.  Nevertheless, worksites of the San Tin EMDC are located more than 300m away from the nearest NSRs as shown in Table 3.4.  Based on the latest construction programme of the San Tin EMDC, the major construction activities would be completed before March 2005.  It is therefore anticipated that cumulative noise impact associated with the San Tin EMDC would be minor and would be unlikely to cause adverse cumulative construction noise impact with the Project.

 

3.32          The proposed channel NTM04 is located to the south of the proposed slip roads, running from Luk Mei Tsuen to San Tin Highway.  Apart from NSRs V18 (about 214m), V19 (about 172m) and V20 (about 105m), the worksites of the NTM04 are located over 300m away from the NSRs as shown in Table 3.4.  According to the Environmental Review Report of Drainage Master Plan Study in the Northern New Territories, the construction works for NTM04 would be small in scale and no adverse noise impact was anticipated.  Hence, adverse cumulative noise impact associated with the construction activities of the NTM04 would not be expected.

 

Operation Phase

 

3.33          The aim of the Project is to improve the capacity of San Tin Interchange by means of elevated roads to segregate the cross-boundary goods vehicles in order to relieve the traffic queues in the existing San Tin roundabout.  During the operation of the Project, the additional slip roads would likely increase the road traffic noise impacts on the nearby NSRs.  Practical direct noise mitigation measures may be required to alleviate the potential noise impact.

 

Evaluation of Impacts

Construction Phase

 

3.34          As shown in the preliminary construction programme, various construction activities would be undertaken concurrently during a particular period.  Cumulative construction noise impacts arising from various construction activities of the Project have been predicted.  The predictions were taken account of distance attenuation, and screening effect from building structures and topographical features.  The results of the predictions are presented in Appendix 3.4.  Table 3.5 summaries the unmitigated cumulative noise levels from various construction activities of the Project at the representative NSRs.

 

Table 3.5         A Summary of Cumulative Construction Noise Impacts (Without Mitigation)

 

NSR ID

Location

Predicted Construction Noise Levels, dB(A)

Sch1

Tun Yu School

70-74

V06

Village house near San Tin Highway

64-88

V10

Village house at Wing Ping Tsuen

61-77

V18

Village house near San Tin Highway

62-83

V19

Village house near San Tin Highway

64-84

V20

Village house near Kwu Tung Road

75-82

V22

Village house near Kwu Tung Road

71-82

V23

Village house near Kwu Tung Road

63-73

V28

Village house near Castle Peak Road

72-74

V30

Village house near Lok Ma Chau Road

70-74

Note: Bold value indicates the exceedance of noise criteria of 75 dB(A) for residential uses, 65 dB(A) for school during examination period.

 

3.35          As indicated in the above table, the cumulative noise levels at the representative NSRs were predicted to range from 61 to 88dB(A).  The results show that the construction noise impacts at some of the NSRs would exceed the EIAO-TM noise criteria.  Therefore, mitigation measures would be required in order to abate the construction noise impact.

 

Operational Phase

 

3.36          Unmitigated road traffic noise levels at the representative NSRs as listed in Table 3.4 have been predicted and are summarised in Table 3.6.  A breakdown of noise contribution from existing and new roads is given in Appendix 3.5.

 

Table 3.6         Predicted Road Traffic Noise Levels in 2022 (Without Mitigation)

 

NSR

Floor

Assessment Level

mPD

Predicted Noise Level, dB(A)

Number of Dwellings/Classrooms Exceed the Noise Criteria

Sch1

G

9.9

8383

9

T01

G

7.3

6363

0

V02

G

15.2

8080

3

 

1

18.2

8181

 

V03

G

12.1

8282

1

V04

G

12.6

8484

6

V05

G

7.1

7979

2

 

1

10.1

8181

 

V06

G

7.1

8181

2

 

1

10.1

8383

 

V07

1

10.3

8282

6

V08

1

10.4

7575

4

V09

G

7.4

7373

1

V10

G

5.1

7272

3

 

1

8.1

7474

 

 

2

11.1

7474

 

V11

G

5.1

7070

4

 

1

8.1

7171

 

 

2

11.1

7272

 

V12

G

4.3

7171

12

 

1

7.3

7272

 

 

2

10.3

7272

 

V13

G

4.3

6969

0

 

1

7.3

6969

 

 

2

10.3

7070

 

V14

G

4.1

6868

0

 

1

7.1

6969

 

V15

G

3.2

6464

0

 

1

6.2

6565

 

 

2

9.2

6666

 

 

3

12.2

6666

 

V16

G

10.7

8383

1

V17

G

13

8080

3

 

1

16

8080

 

 

2

19

8080

 

V18

G

7.7

8282

1

V19

G

6.3

8282

2

 

1

9.3

8383

 

V20

G

5.2

7373

2

V22

G

9.8

7575

3

 

1

12.8

7777

 

V23

G

9.8

7777

3

V24

G

15.2

7777

3

 

1

18.2

7777

 

 

2

21.2

7777

 

V25

G

11.6

7676

2

 

1

14.6

7979

 

V26

G

19.2

7878

2

 

1

22.2

8181

 

V27

G

8.9

8282

2

 

1

11.9

8383

 

V28

G

7.6

8080

4

 

1

10.6

8080

 

V29

G

4.7

7070

0

 

1

7.7

7070

 

 

2

10.7

7070

 

V30

G

6.5

6868

0

P01

G

5.1

80

--

 

1

8.1

81

 

 

2

11.1

80

 

P02

G

5.1

76

--

 

1

8.1

78

 

 

2

11.1

78

 

P03

G

5.1

76

--

 

1

8.1

76

 

 

2

11.1

75

 

P04

1

6.8

73

--

 

3

12.432

74

 

 

6

20.860.8

75

 

P05

1

6.8

73

--

 

310

12.432

7574

 

 

620

20.860.8

7575

 

P06

1

6.8

73

--

 

310

12.432

7574

 

 

620

20.860.8

7575

 

P07

1

6.8

72

--

 

310

12.432

7372

 

 

620

20.860.8

7372

 

Note:  Bold value indicates the exceedance of EIAO-TM noise criteria of 70dB(A) for residential uses or 65dB(A) for schools and places of worship

             --     Not Applicable

 

3.37          The above table indicates that the unmitigated road traffic noise levels at the representative NSRs were predicted to range from 61 63 to 84 dB(A).  Apart from a few NSRs located far away from the nearby road networks or screened by building structures/topographical features, the noise levels at most of the NSRs would exceed the EIAO-TM noise criteria.  The following sections detail the potential traffic noise impacts at the representative NSRs.  

 
Existing Residential NSRs (V02 - V20, V22 - V30)

 

3.38          The predicted noise levels at existing residential NSRs V02-V20 and V22-V30 range from 61 63 to 84 dB(A).  The results indicated that the overall noise levels at NSRs V02– V12, V16 – V20 and V22 – V28 would exceed the EIAO-TM noise criterion.  However, the breakdown of the overall noise levels in Appendix 3.5 shows that the noise levels from the new roads at all these NSRs would be below the EIAO-TM noise criterion and the new road contribution would be less than 1.0 dB(A), except the first floor of NSR V05 and NSR V06 at which the noise levels from new roads were predicted to exceed the noise criterion.  Hence, mitigation measures were considered necessary for these NSRs.

Future/planned NSRs (P01 – P07)

 

3.39          The predicted noise levels at the future/planned NSRs (P01-P07) in the ‘V’ Zone and ‘OU(CDWEA)’ Zone were predicted in the range of 72 to 81 dB(A), exceeding the EIAO-TM noise criterion.  The breakdown of the overall noise levels indicates that the exceedances are partially attributable to the new existing roads, except NSRs P04 P06.  Mitigation measures were therefore considered necessary.

School and Temple

 

3.40          As indicated in Table 3.6, the overall noise level at the Temple (T01) would comply with the EIAO-TM noise criterion of 65 dB(A) dB(A).  For Tun Yu School (Sch1), exceedances of the EIAO-TM noise criterion were predicted, whereas the exceedances are attributable to the existing roads.  The breakdown of the overall noise levels shows that the noise levels from the new roads would be well below the EIAO-TM noise criterion of 65 dB(A) and the new road contribution to the overall noise levels would be less than 1.0 dB(A).  Hence, mitigation measures were not considered. 

 

Mitigation of Adverse Environmental Impacts

Construction Phase

 

3.41          In order to alleviate the potential noise impact from the construction activities of the Project, the following mitigation measures have been considered:

 

·        Good Site Practice

·        Use of quiet PME; and

·        Adoption of movable noise barriers.

 

Good Site Practices

 

3.42          Good site practices and noise management can considerably reduce the impact of construction site activities on nearby NSRs.  The noise benefits of these practices can vary according to specific site conditions and operations.  Since the effect of the good site practices could not be quantified, the mitigated noise levels calculated in the subsequent sections have not taken account of this effect.  The following site practices should be followed during each phase of construction:

 

·        All plant operated on-site should be well maintained and plant should be serviced regularly during the construction works;

·        Machines and plant that may be in intermittent use should be shut down between work periods or should be throttled down to a minimum;

·        Plant known to emit noise strongly in one direction should, where possible, be orientated to direct noise away from the NSRs;

·        Mobile plant should be sited as far away from NSRs as possible; and

·        Material stockpiles and other structures should be effectively utilised, where practicable, to screen noise from on-site construction activities.

 

Use of Quiet PME

 

3.43          The use of quiet PME was considered to be a practicable means to abate the potential construction noise impact.  The Contractor would be able to obtain particular models of plant that are quieter than the SWLs in the GW-TM.  The noise reduction achieved in this way will depend on the Contractor’s chosen construction methods and it is considered that specifying particular plant models would be too restrictive to Contractor’s preferred construction methods.  Hence, it is preferable and practical to specify the overall noise performance specification of all plant on site for various construction activities given in Appendix 3.7on site in terms of the total SWL so that the Contractor is allowed some flexibility to select plant to suit his needs. 

 

3.44          Quiet plant is defined as a PME having actual SWL lower than the value specified in the GW-TM.  Examples of quiet PME taken from the BS5228: Part 1: 1997 are given in Table 3.7 below.

 

Table 3.7         Sound Power Levels for Specific Quiet PME

 

PME

BS5228

SWL/Item, dB(A)

Backhoes

Table C3, item 97

105

Dump Truck

Table C9, item 39

103

10T Roller

Table C8, item 30

101

3T Roller

Table C8, item 25

96

30T Crane

Table C7, item 112

102

100T Crane

Table C.7, item 105

108

Segments Carriers

Table C3, item 59

105

Paver

Table C8, item 24

101

Hydraulic Breaker

Table C8, item 13

110

Rubber Tyre Roller

Table C8, item 25

96

 

3.45          With the adoption of the quiet PME, the total SWLs for various construction activities are given in Appendix 3.6.  Mitigated noise levels at the representative NSRs were predicted and are presented in Appendix 3.7.  Table 3.8 summarises the mitigated cumulative noise levels from various construction activities of the Project at the representative NSRs.


 

Table 3.8         A Summary of Cumulative Construction Noise Impacts (Mitigated – Use of Quiet PME)

 

NSR ID

Location

Predicted Construction Noise Levels, dB(A)

Sch1

Tun Yu School

60-64

V06

Village house near San Tin Highway

57-79

V10

Village house at Wing Ping Tsuen

52-69

V18

Village house near San Tin Highway

53-75

V19

Village house near San Tin Highway

55-74

V20

Village house near Kwu Tung Road

65-77

V22

Village house near Kwu Tung Road

62-74

Note: Bold value indicates the exceedance of noise criteria of 75 dB(A) for residential uses, 70 dB(A) for school during normal hour

 

3.46          As indicated in Table 3.8, exceedances of the EIAO-TM noise criterion at NSRs V06 and V20 were still predicted with the implementation of the quiet PME.  Hence, further mitigation measures in the form of movable noise barriers were considered.

 

Adoption of Movable Noise Barriers

 

3.47          The use of noise barriers would be an effective means to alleviate the noise impact arising from the construction works, particularly for low-rise NSRs.  In view of the low-rise nature of the NSRs, movable noise barriers of 3 to 5 m high (depending on the size of the plant that requires to be screened) with skid footing should be used and located within a few metres of stationary plant and mobile plant such that the line of sight to the NSR is blocked by the barriers.  The length of the barriers should be at least five times greater than its height. These movable noise barriers could produce at least 5 dB(A) noise reduction for mobile plant such as backhoe, roller and crane as well as large scale plant such crane with oscillators and chisel.  With reference to the booklet entitled A Practical Guide for the Reduction of Noise from Construction Works, the noise barrier material should have a superficial surface density of at least 7 kg/m2.  Figure 3.5 shows the approximate locations of the proposed movable noise barriers during construction phase.

 

3.48          Appendix 3.8 shows the SWLs of various construction activities with the use of quiet PME and movable noise barriers.  Based on Appendix 3.8, mitigated noise levels at the representative NSRs were calculated and the results are given in Appendix 3.9.  Table 3.9 summarises the mitigated cumulative noise levels predicted at NSRs V06 and V20.

 

 

Table 3.9         A Summary of Cumulative Construction Noise Impacts (Mitigated – Use of Quiet PME and Movable Noise Barriers)

 

NSR ID

Location

Predicted Construction Noise Levels, dB(A)

V06

Village house near San Tin Highway

57-75

V20

Village house near Kwu Tung Road

64-74

Note: Bold value indicates the exceedance of noise criteria of 75 dB(A) for residential uses

 

3.49          The results indicate that with the adoption of the recommended mitigation measures, no exceedance of the EIAO-TM noise criteria at NSRs V06 and V20 would be anticipated.  Hence, no further mitigation would be required.

 


Operational Phase

 

Consideration of At-source Direct Mitigation Measures
Traffic Management

 

3.50          Traffic management in terms of limiting the use of heavy vehicles along the proposed slip roads and/or reducing vehicle speed may be a possible mean of noise mitigation.  Nevertheless, since the aim of the Project is to improve the capacity of San Tin Interchange by means of the proposed slip roads to segregate the cross-boundary goods vehicles in order to relieve the traffic queues in the existing San Tin roundabout, restricting the use of the slip roads by heavy vehicles and a further reduction in the vehicle speed to below 50 km/h would undermine the role and capacity of the Project.  Hence, noise mitigation by means of traffic management was considered not appropriate.

Low Noise Road Surfacing

 

3.51          The use of low noise road surfacing (LNRS) for the proposed slip roads has been considered.  In accordance with the CRTN, the use of pervious macadam on road surface can reduce the basic noise level by 3.5 dB(A), while the use of impervious bituminous and concrete can only give 1 dB(A) noise reduction.  Nevertheless, based on the Guidance Notes on Noise Reducing Road Surfacing issued by Highways Department (July 2001), the application of LNRS on low speed roads (equal to 50km/h or below) should be subject to the following conditions:

·        Not on inclined roads;

·        No sharp bend in road geometry;

·        Average Annual Daily Traffic not exceeding 18,500 in traffic volume and percentage of heavy vehicles not exceeding 35%; and

·        Not on roads where a minimum crossfall of 2.5% cannot be practically achieved to drain water to the roadside gullies effectively.

 

3.52          According to the engineering design, the proposed speed limit for the slip roads would be 50 km/h and a significant portion of the slip roads would be inclined.  In addition, the traffic using the slip roads would be all heavy vehicles (i.e. 100%).  As such, it was considered not appropriate and practicable to apply LNRS on the slip roads in view of the need of frequent resurfacing and high maintenance cost.

Roadside Noise Barriers

 

3.53          The use of noise barriers to mitigate the traffic noise impact associated with the Project at the affected NSRs has been considered practicable.  The following noise barriers were recommended:

 

For protecting existing NSRs

 

·        A 1.5m high reflective plain barrier of about 121m long erected along the western edge of Slip Road A.

 

For Future/Planned NSRs

 

·        A 5m high cantilevered barrier with 2m cantilever at 45 o (reflective) of about 30m long be erected at the junction of Castle Peak Road and slip road of San Tin Highway.

 

·        A 4.25m high reflective plain barrier of about 303m be erected along Slip Road F.

 

3.54          Only footings of the barriers for the future/planned NSRs are required before the operation of the ProjectThe barriers would be provided are only required before the occupation of the planned residential premises.  Locations of the recommended noise barriers and its typical cross-sections are illustrated in Figures 3.6 and 3.7.  The detailed design of the recommended roadside noise barriers should be submitted to ACABAS for consideration before implementation.

 

3.55          The mitigated traffic noise levels at the representative NSRs have been calculated and are summarised in Table 3.10.  A breakdown of noise contribution from the existing and new roads is given in Appendix 3.5. 

 

Table 3.10       Predicted Road Traffic Noise Levels in 2022 (With Mitigation)

 

NSR

Floor

Assessment Level

mPD

Predicted Noise Level, dB(A)

Mitigation – Existing NSRs

Mitigation – Existing & Future/Planned NSRs

Sch1

G

9.9

8383

8383

T01

G

7.3

6363

6363

V02

G

15.2

8080

8080

 

1

18.2

8181

8181

V03

G

12.1

8282

8282

V04

G

12.6

8484

8484

V05

G

7.1

7676

7676

 

1

10.1

7979

7979

V06

G

7.1

7777

7777

 

1

10.1

8181

8181

V07

1

10.3

8282

8282

V08

1

10.4

7474

7474

V09

G

7.4

7373

7373

V10

G

5.1

7171

7171

 

1

8.1

7373

7373

 

2

11.1

7474

7473

V11

G

5.1

7070

7070

 

1

8.1

7171

7171

 

2

11.1

7171

7171

V12

G

4.3

7171

7171

 

1

7.3

7171

7171

 

2

10.3

7272

7271

V13

G

4.3

6969

6968

 

1

7.3

6969

6969

 

2

10.3

7070

6969

V14

G

4.1

6868

6867

 

1

7.1

6969

6868

V15

G

3.2

6464

6363

 

1

6.2

6565

6564

 

2

9.2

6666

6565

 

3

12.2

6666

6665

V16

G

10.7

8383

8383

V17

G

13

8080

8080

 

1

16

8080

8080

 

2

19

8080

8080

V18

G

7.7

8383

8383

V19

G

6.3

8282

8282

 

1

9.3

8383

8383

V20

G

5.2

7373

7373

V22

G

9.8

7575

7575

 

1

12.8

7777

7777

V23

G

9.8

7777

7777

V24

G

15.2

7777

7777

 

1

18.2

7777

7777

 

2

21.2

7777

7777

V25

G

11.6

7676

7676

 

1

14.6

7979

7979

V26

G

19.2

7878

7878

 

1

22.2

8181

8181

V27

G

8.9

8282

8282

 

 

11.9

8383

8383

V28

G

7.6

8080

8080

 

1

10.6

8080

8080

V29

G

4.7

7070

7070

 

1

7.7

7070

7070

 

2

10.7

7070

7070

V30

G

6.5

6868

6868

P01

G

5.1

80

80

 

1

8.1

81

81

 

2

11.1

80

80

P02

G

5.1

76

7671

 

1

8.1

78

7874

 

2

11.1

78

7875

P03

G

5.1

76

75

 

1

8.1

76

75

 

2

11.1

75

75

P04

1

6.8

73

6967

 

103

3212.4

7674

7274

 

206

60.820.8

7675

7475

P05

1

6.8

73

7068

 

310

12.432

7574

7274

 

620

20.860.8

75

7474

P06

1

6.8

73

7171

 

310

12.432

7574

7374

 

620

20.860.8

75

7474

P07

1

6.8

72

7272

 

310

12.432

72

7272

 

620

20.860.8

7372

7273

Note:  Bold value indicates the exceedance of EIAO-TM noise criteria of 70dB(A) for residential uses or 65dB(A) for schools and places of worship

 

3.56          With the implementation of the recommended noise barriers, most of the NSRs would still be exposed to traffic noise impact exceeding the EIAO-TM noise criteria.  However, the results indicate that the exceedances are attributable to the existing roads.  The breakdown of the overall noise levels in Appendix 3.5 shows that the noise levels from the new roads at all the representative NSRs (both existing and future/planned NSRs) would be below the EIAO-TM noise criteria and the increase in the overall noise levels from the new roads would be less than 1.0 dB(A).  Hence, no further mitigation would be required.

 

Side Effects and Constraints of the Proposed Roadside Noise Barrier

 

3.57          The locations of the proposed noise barriers were checked against road safety requirements.  The criteria for visibility at a height of 1.05 m above the road surface at road junctions and vehicular run-ins as stipulated in the Transport Planning and Design Manual (TPDM) have been followed for safety reasons.  It was confirmed that the proposed barrier design would not pose any sightline problem to the motorist.  

 

3.58          Having considered that the proposed noise barriers were reflective plain/cantilevered barriers, potential side effects such as air quality impact associated with the barriers were considered minor and would be acceptable.  

 

Construction Works During Restricted Hours

 

3.59          As mentioned in Section 3.27, night-time work would be required for the erection of precast concrete viaduct segments crossing/encroaching into San Tin Highway and therefore would be under the control of the GW-TM.  An indicative assessment has been undertaken to investigate the potential noise impact from the construction activities which would be performed in restricted hours in accordance with the criteria and methodology stated in the GW-TM.

 

3.60          The ASRs depend on the exact locations, orientations of the NSRs with respect to the construction activities and potential screening from structures or topographical features.  For the purpose of this indicative assessment, the ASRs for each of the NSRs likely to experience noise from construction works during restricted hours have been determined in accordance with the GW-TM, based on the current information available.  Since the NSRs V10, 19 and 20 would be the closest NSRs to the worksites of the night-time works, they were selected for the indicative assessment as the worst-case scenarioTable 3.11 shows the ASRs for each of the NSRs selected for the indicative assessment.

 


Table 3.11       Area Sensitivity Ratings for NSRs Selected for the Indicative Assessment

 

NSR

Influencing Factor (IF)

Degree to which NSR is affected by IF

ASR

V10

San Tin Highway

Directly

B

V19

San Tin Highway

Directly

B

V20

San Tin Highway

Directly

B

 

3.61          For ASR of B, the evening and night-time noise criteria as specified in GW-TM are 65dB(A) and 50dB(A), respectively.  An indicative assessment for the construction work during restricted hours has been carried out and the results are presented in Appendix 3.10. 

 

3.62          The results indicate that with the adoption of mitigation measures including quiet equipment, and movable/temporary noise barriers (Figure 3.8), the predicted noise levels at the NSRs would comply with the evening noise criterion, whereas 3-5dB(A) exceedances of the night-time noise criterion were predicted.  In view of the nature of the work, it was considered that all the feasible and practicable direct mitigation measures have been exhaustedly deployed at the time of preparing this report. 

 

3.63          Based on the engineering design, the erection of precast concrete viaduct segments crossing/encroaching into existing roads would adopt balance-cantilevering method.  The erection of precast concrete viaduct segments would require a launching girder or mobile crane for mobilizing the precast concrete segments and segment carriers for transporting the bridge segments.  It was anticipated that about 5 continuous nights would be required for completing the works.  As required by Transport Department and the Police Force, no live traffic should be underneath the launching operation for safety reasons.  Therefore, this construction activity can only be carried out when the roads are closed to public traffic.  In order to reduce the interruption or disturbance to the traffic during closure of the roads, this activity should be undertaken during the night-time period.  Hence, this construction activity would be subject to unavoidable constraints to be carried out during night-time in order to avoid the traffic interruption or disturbance of the major roads.

 

3.64          According to the GW-TM, a CNP may be granted if the construction noise levels exceeds the acceptable noise levels provided that it can be demonstrated to the satisfaction of the Noise Control Authority that less public annoyance or inconvenience would be resulted if the works are undertaken during restricted hours than non-restricted hours.  Notwithstanding this, Contractors are still recommended to adopt best practicable measures to minimise the construction noise impact on NSRs as far as practicable. 

 

3.65          Despite any description made in this EIA study on construction noise aspects, there is no guarantee that a Construction Noise Permit (CNP) will be issued for the project construction. The Noise Control Authority will consider a well-justified CNP application, once filed, for construction works within restricted hours as guided by the relevant Technical Memoranda issued under the Noise Control Ordinance. The Noise Control Authority will take into account of contemporary conditions/situations of adjoining land uses and any previous complaints against construction activities at the site before making his decision in granting a CNP. Nothing in this Environmental Report shall bind the Noise Control Authority in making his decision. If a CNP is to be issued, the Noise Control Authority shall include in it any condition he thinks fit. Failure to comply with any such conditions will lead to cancellation of the CNP and prosecution action under the NCO.

 

 

Residual Environmental Impacts

Construction Phase

 

3.66          With the implementation of the recommended mitigation measures, the cumulative construction noise levels from the concurrent construction activities of the Project would comply with the EIAO-TM noise criteria.  No residual impact is anticipated.

 


Operational Phase

 

Existing NSRs

 

3.67          It was estimated that 4 existing residential dwellings would benefit from the proposed noise barrier by 2-4dB(A) noise reduction.  Owing to the high noise levels from traffic along the existing roads, most of the existing NSRs would be exposed to overall traffic noise levels exceeding the EIAO-TM noise criteria even with the implementation of the recommended noise mitigation measures.  Since the residual impacts are attributable to the existing roads, any further direct mitigation applied to the proposed slip roads was considered ineffective, and hence further direct mitigation would not be considered.

 

3.68          In order to redress the residual impacts, ITR in the form of window insulation and provision of air-conditioning may need to be considered subject to the eligibility assessment results and approval from the ExCo.  The residual impacts at these existing NSRs have been assessed against the noise insulation criteria as stated in Section 3.7 and the results are presented in Appendix 3.11.  The results of the eligibility assessment show that no existing NSRs would be eligible for the ITR.

 

Future/Planned NSRs

 

3.69          With the implementation of the proposed direct noise mitigation measures, most of the Future/Planned NSRs would exceed the EIAO-TM noise criterion.  Nevertheless, the residual impacts are attribute to the existing roads.  The noise impact from the proposed slip roads would be well below the EIAO-TM noise criterion and contribute less than 1.0dB(A) to the overall noise levels.

 

Environmental Monitoring and Audit Requirements

Construction Phase

 

3.70          Owing to the potential noise impact arising from the construction activities of the Project on the nearby noise sensitive receivers, it is recommended that Environmental Monitoring and Audit (EM&A) be undertaken during the construction phase of the Project.  The EM&A is required to monitor the compliance with permissible noise levels and to check the effectiveness of the recommended mitigation measures.  Details of the EM&A are provided in a stand-alone EM&A Manual.

 


Operational Phase

 

3.71          It is recommended that traffic noise monitoring be carried out to check the effectiveness of the direct mitigation measure for road traffic noise impact.  The monitoring procedures and locations are presented in the EM&A Manual.

 



[1]             Sheung Shui to Lok Ma Chau Spur Line Environmental Impact Assessment Final Report. January 2002. KCRC