5            NOISE

 

5.1                   Identified Sensitive Receivers

 

5.1.1             Representative Noise Sensitive Receivers (NSRs) have been identified in accordance with criteria set out in the Environmental Impact Assessment Ordinance (EIAO) and Technical Memorandum on the Environmental Impact Assessment Process (TMEIA).

 

5.1.2             Preliminary NSRs have been identified in an area 300m either side of the full stretch of the proposed roads.  Existing noise sensitive receivers who may be adversely affected by increases in noise as a result of the construction and operation of the improved Tung Chung Road are listed in Table 5.1. The representative NSRs can also be seen in Figures 5.1a to 5.1g.  The density of village properties in the Tung Chung Valley, Ha Ling Pei and Wong Ka Wai, has made it necessary to allocate further sensitive receivers in this area for the assessment of construction noise for permanent noise barrier construction and operational noise impacts.  The additional sensitive receivers in this area are shown in Figure 5.3a.  Visitors to the country park are also potentially sensitive to impacts but as no permanent facilities, such as camp grounds, are affected and all other visitors would be transient in nature, no significant impacts are predicted.

 

5.1.3             In addition to the above, the Cheung Sha Layout Plan – Lantau Island, Plan No. L/I-CS/1, has identified several future sales sites in the vicinity of the junction of the new Tung Chung Road with the South Lantau Road.  These sites have been allocated for future low rise 2 storey residential development. The boundaries of the site are indicative only and the layout of the properties is not known at this time.  However, representative locations at the sites which are closest to the proposed road have been selected at the site boundaries in order to assess the potential impacts to any future receivers, as shown on Figure 5.1e.  The properties will not be constructed and occupied until after the opening of the proposed widened Tung Chung Road and as such the representative ASRs are relevant to the operational phase of the project only.

 

Table 5.1:                   Noise Sensitive Receivers

 

Figures No.

NSR Ref.

NSR

No. of Floor

Shortest Slant Distance (m)

Description

5.1a/5.3a

SR1

8, Ha Ling Pei

3

235

Residential

SR2

7, Wong Ka Wai

3

119

Residential

SR3

Village House

3

256

Residential

SR4

8, Lung Tseng Tau

3

56

Residential

SR5

Village House

3

168

Residential

5.1b

SR6

41, Shek Lau Po

3

246

Residential

SR7

Village House

3

198

Residential

SR8

1, Shek Mun Kap

3

230

Residential

5.1c

SR9

AFCD Staff Quarters

1

156

Residential

 

 

 

 

 

 

 

 

 

 

 

 

5.1d

SR10

74, Leyburn Villas

2

298

Residential

5.1e

SR11

12, Cheung Sha Sheung Tsuen

3

277

Residential

SR12

32, Cheung Sha Sheung Tsuen

3

266

Residential

SR13

31B, South Lantau Road

2

35

Residential

SR14

Village House

2

153

Residential

SR15

YWCA Youth Camp

1

55

Residential

5.1f

SR16

Block 1, Acacia Villa

3

161

Residential

SR17

37, South Lantau Road

3

234

Residential

SR18

39, South Lantau Road

3

289

Residential

5.1g

SR19

Block 17, Butterfly Crest

3

#

Residential

Additional Sensitive Receivers in Tung Chung Valley

5.3a

SR1A

10, Ha Ling Pei

3

273

Residential

SR1B

8, Ha Ling Pei

3

256

Residential

SR1C

7, Ha Ling Pei

3

215

Residential

SR2A

14, Wong Ka Wai

3

165

Residential

SR2B

9, Wong Ka Wai

3

132

Residential

SR2C

7, Wong Ka Wai

3

99

Residential

SR2D

3A, Wong Ka Wai

3

83

Residential

SR4A

10A, Lung Tseng Tau

3

60

Residential

SR4B

7, Lung Tseng Tau

3

45

Residential

SR4C

13, Lung Tseng Tau

3

55

Residential

SR4D

28, Lung Tseng Tau

3

34

Residential

Future Sensitive Receivers in Cheung Sha(1)

5.1f

CS1

Cheung Sha future sale site

2

35(2)

Residential

CS2

Cheung Sha future sale site

2

32(2)

Residential

CS3

Cheung Sha future sale site

2

56(2)

Residential

CS4

Cheung Sha future sale site

2

53(2)

Residential

CS5

Cheung Sha future sale site

2

25(2)

Residential

CS6

Cheung Sha future sale site

2

20(2)

Residential

CS7

Cheung Sha future sale site

2

20(2)

Residential

CS8

Cheung Sha future sale site

2

25(2)

Residential

CS9

Cheung Sha future sale site

2

29(2)

Residential

CS10

Cheung Sha future sale site

2

33(2)

Residential

CS11

Cheung Sha future sale site

2

50(2)

Residential

CS12

Cheung Sha future sale site

2

22(2)

Residential

CS13

Cheung Sha future sale site

2

42(2)

Residential

Note:      #  The distance between SR19 and the improved Tung Chung Road is more than 500m and thus it will only be potentially affected by the slope remediation works on the obsolete sections of the existing Tung Chung Road during the construction phase

                        (1): Future sensitive receivers relevant to the operational phase only.

                (2): Based upon assumed locations of sensitive receivers only and site boundaries are indicative.

 

5.1.4             All the sensitive receivers are residential and, thus, the noise criteria for general construction work during normal working hours (0700 to 1900 hours on any day not being Sunday and Public Holiday) will be 75 dB(A) (Leq (30mins)) and 70 dB(A) (L10(1hour)) for the operational phase as detailed in Section 3.

 

5.1.5             The Remaining Development in Tung Chung and Tai Ho Comprehensive Feasibility Study has also proposed sensitive development on the fringes of Tung Chung, close to the northern edge of the project and these could be adversely affected by the operation of the improved Tung Chung Road. The impacts on these sensitive receivers are reported separately in Section 12 of this report.

 

5.2                   Baseline Conditions

 

5.2.1             The majority of the proposed road, with the exception of the northern and southern end, is situated within very quiet rural areas, with the surrounding land comprising country parks, open space and agricultural activities.  Noise levels for the majority of the study area are very low, the only major noise sources is the traffic of existing Tung Chung Road.

 

5.2.2             Noise levels at the northern end of the alignment in Tung Chung are influenced by traffic from the Yu Tung Road and existing Tung Chung Road.  The southern end of the alignment connects with the South Lantau Road and thus, noise levels in this area are higher due to the presence of road traffic.

 

5.3                   The Proposed Scheme

 

5.3.1             Construction Activities

 


5.3.1.1       The construction equipment for each stage of the project has been determined and the sound power level (SWL) of each piece of equipment is based upon the Technical Memorandum on Noise From Construction Work Other Than Percussive Piling and BS5228 when the SWL are not listed in the Technical Memorandum.  No percussive piling is anticipated for the Project.

 

5.3.1.2       The construction activities for the Project can be divided into four broad areas, namely roadworks and bridgeworks for the main alignment, slope stabilisation works and slope remediation works for the obsolete section of the existing Tung Chung Road.  The key construction activities within these broad activities will include:

 

(i)                    Roadworks                       -        earthworks

             (including utility works)      -        retaining wall construction (required for all

                                                               areas not on structure); and

-                pavement construction.

 

               (ii)         Bridgeworks:                    -        foundation construction; and

                                                                     -        deck construction.

              

               (iii)         Slope Stabilisation -          soil nailing/rock dowelling; and

-             equipment transportation.

-              

               (iv)        Slope Remediation -            earthworks; and

-             slope nailing.

 

               (v)         Noise Mitigation                   -    foundation construction; and

                                                                        -    erection.

5.3.1.3       The individual pieces of equipment required for each of these stages have been highlighted in Section 2.  The construction plant has been further divided into working scenarios for each of the broad construction activities as detailed in Table 5.2 below:

 

Table 5.2:              Equipment Scenarios

 

Main Activity

Sub-Activity

Equipment Scenario

Scenario Reference

Roadworks

Earthworks(1)

Scenario 1 - Rock/earth excavation

E1

Scenario 2 -  Removal /spreading of earth/rock

E2

Scenario 3 - Forming of earthworks.

E3

Retaining Wall

Construction

Scenario 1 - Foundation works

R1

Scenario 2 - Piling

R2

Scenario 3 - Formwork/concreting.

R3

Scenario 4 - Backfilling Works

R4

Pavement

Construction

(1)

Scenario 1 - Preparation of Roadbase

P1

Scenario 2 - Laying of Surface Material

P2

Scenario 3 - Road Marking

P3

Bridgeworks

Foundation

Construction

Scenario 1 - Excavation

F1

Scenario 2 - Piling

F2

Scenario 3 - Formwork

F3

Scenario 4 - Concreting

F4

Deck Construction

Scenario 1 - Formworks

D1

Scenario 2 - Concreting

D2

Scenario 3 - Deck elevation

D3

Slope(2)

Stabilisation

Rock Dowelling

Scenario 1 – Rock dowelling

SS1

Equipment Transportation

Scenario 1 – Delivery by helicopter

SS2

Slope (2)

Remediation

Earthworks

Scenario 1 – Earthworks

SR1

Slope Nailing

Scenario 1 – Slope Nailing

SR2

Noise Mitigation

Foundations and Erection

Scenario 1 – Foundation Works

NB1

Scenario 2 – Piling

NB2

Scenario 3 – Formwork/Concreting

NB3

Scenario 4 – Backfilling Works

NB4

Scenario 5 - Erection

NB5

Notes        (1): Includes minor works associated with utilities.

              (2): No drainage works are required for the slope stabilisation works.  Noise associated with the drainage and shotcreting works for the remediation of slopes on the existing Tung Chung Road are considered to be minor but covered in Table 5.8d. 

 

5.3.1.4       The equipment included in each of these scenarios, together with the appropriate sound power levels are provided in Tables 5.3 to 5.7 below for roadworks, bridge works, slope stabilisation works, slope remediation works and noise mitigation works respectively. As noted, in Section 2.7.2, the equipment lists have been confirmed by the Project Proponent as being practical for completing the works.

 

Table 5.3:              Typical Equipment Requirement for Road Construction

 

CNP

Equipment Code

Equipment Scenario

Sound Power

Level (SWL) in dB(A)

Number of Equipment

 

Total Sound Power Level (SWL) in dB(A)

Earthworks

Scenario E1

Excavation of earth / rock and removal

028

Breaker

122

2

125.9

067

Dump Truck

117

1

081

Excavator

112

1

282

Water Pump (Petrol)

103

1

Scenario E2

Spreading of earth / rock          

030

Bulldozer

115

1

119.5

067

Dump Truck

117

1

204

Scraper

109

1

 

 

Scenario E3

Forming of earthworks

030

Bulldozer

115

1

120.7

104

Grader

113

1

067

Dump Truck

117

1

186

Roller Vibratory

108

1

050

Compactor

105

1

169

Power Rammer (Petrol)

108

1

Retaining wall con­­­­­­­­struction

 

Scenario R1

Foundation works

 

028

Breaker

122

2

125.9

067

Dump Truck

117

1

081

Excavator

112

1

282

Water Pump (Petrol)

103

1

Scenario R2(1)

Piling

 

 

 

164

Piling Rig

115

1

116.9

282

Water Pump

103

1

141

Lorry

112

1

165

Piling, large diameter bored, oscillator *

115

1

Scenario R3

Formwork / concreting

044

Concrete Lorry Mixer

109

1

117.9

170

Poker

113

1

101

Generator

108

1

201

Saw, circular

108

1

282

Water pump

103

1

043

Chipper

112

1

066

Dumper

106

1

 

 

 

 

 

 

 

 

 

 

CNP

Equipment Code

Equipment Scenario

Sound Power

Level (SWL) in dB(A)

Number of Equipment

Total Sound Power Level (SWL) in dB(A)

Scenario R4

Backfilling works

050

Compactor Vibratory

105

1

117.8

067

Dump Truck

117

1

186

Roller Vibratory

108

1

 

Pavement Construction

 

Scenario P1

Preparation of Roadbase

186

Vibratory roller

108

1

118.6

067

Dump truck

117

1

081

Excavator

112

1

Scenario P2

Laying of Surface Material

 

004

Asphalt paver

109

1

119.0

185

Road roller

108

1

067

Dump Truck

117

1

186

Vibratory roller

108

1

044

Concrete Lorry Mixer

109

1

Scenario P3

Road Marking

 

161

Paint line marker

90

1

115.0

203

Saw

115

1

*       The piling oscillator will be required to be used with the piling rig (CNP 164).  However, as these pieces of equipment will be used alternately and never concurrently, the total SWL has been based upon the SWL of only one piece of equipment (ie one SWL of 115 only). 

(1)     The equipment which will be used for the detailed ground investigation will be similar to that required for the bored piling.  However, the bored piling rig will be noisier than the rig used for the ground investigation.

 

Table 5.4:              Typical Equipment Requirement for Bridge Construction

 

CNP

Equipment Code

Equipment Scenario

Sound Power

Level (SWL) in dB(A)

Number of Equipment

Total Sound Power Level (SWL) in dB(A)

Deck Construction

Scenario D1

Formwork

 

 

021

Bar Bender and cutter

90

1

119.8

171

Planer

117

1

101

Generator

108

1

201

Saw

108

1

043

Chipper, hand-held

112

1

141

Lorry

112

1

Scenario D2

Concreting

044

Concrete lorry mixer

109

1

115.5

047

Concrete pump

109

1

170

Poker

113

1

Scenario D3

Elevation  

 

 

048

Crane

112

1

112.0

 

Foundation/Pier Construction

Scenario F1

Excavation

027

Breaker

122

2

125.9

067

Dump truck

117

1

081

Excavator

112

1

282

Water Pump

103

1

Scenario F2

Piling

 

 

164

Piling Rig

115

1

119.1

283

Water Pump

85

1

067

Dump Truck

117

1

165

Piling, large diameter bored, oscillator*

115

1

Scenario F3

Formwork

021

Bar Bender

90

1

118.0

171

Planer

117

1

101

Generator

108

1

201

Saw

108

1

Scenario F4

Concreting

 

 

047

Concrete pump

109

1

115.5

044

Concrete lorry mixer

109

1

170

Poker

113

1

*       The piling oscillator will be required to be used with the piling rig (CNP 164).  However, as these pieces of equipment will be used alternately and never concurrently, the total SWL has been based upon the SWL of only one piece of equipment (ie one SWL of 115 dB(A) only). 

 

Table 5.5            Typical Equipment Requirement for Slope Stabilisation Works

 

CNP

Equipment Code

Equipment Scenario

Sound Power

Level (SWL) in dB(A)

Number of Equipment

Total Sound Power Level (SWL) in dB(A)

Rock Dowelling

Scenario SS1

Rock Dowelling

183

Rock Drill, hand held

116

1

116.3

003

Compressor

104

1

Equipment Transportation

Scenario SS2

Delivery by Helicopter(1)            

(1)            The assessment of helicopter noise has been based upon the Lmax for typical helicopter models and not the SWL.

 

 

 

 

 

 

 

               Table 5.6            Typical Equipment Requirement for Slope Remediation Works

 

 

CNP

Equipment Code

 

Equipment Scenario

 

Sound Power

Level (SWL) in dB(A)

Number of Equipment

Total Sound Power Level (SWL) in dB(A)

Slope Remediation Earthworks

Scenario SR1

 

Earthworks

081

Excavator

112

1

118.2

067

Dump Truck

117

1

Slope Nailing

Scenario SR2

Slope Nailing

183

Rock Drill, hand held

116

1

116.3

003

Compressor

104

1

 

Table 5.7      Typical Equipment Requirement for the Construction of Permanent Noise Barrier in Tung Chung Valley

 

 

CNP

Equipment Code

 

Equipment Scenario

 

Sound Power

Level (SWL) in dB(A)

Number of Equipment

Total Sound Power Level (SWL) in dB(A)

 

Noise Barrier Con­­­­­­­­struction

 

 

 

Scenario NB1

 

Foundation works

 

 

 

Scenario NB1A

 

026

 

Breaker, Hand Held

114

1

114.3

 

002

 

Air compressor

 

102

1

 

Scenario NB1B

 

081

 

Excavator

 

112

1

112.5

 

282

 

Water Pump

 

103

1

 

Scenario NB1C

141

Lorry with grab#

112

1

 

112.0

 

Scenario NB2

 

Piling

 

 

 

-

 

Mini Piling Rig*

 

113

1

1

113.4

 

282

 

Water Pump

 

103

1

1

 

Scenario NB3

 

Formwork / concreting

 

 

 

044

 

Concrete Lorry Mixer

 

109

1

114.8

 

170

 

Poker

 

113

1

 

282

 

Water pump

 

103

1

 

Scenario NB4

 

Backfilling works

 

 

 

Scenario NB4A

 

050

 

Compactor Vibratory

 

105

1

105.0

 

Scenario NB4B

 

141

Lorry with grab#

112

1

112.0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Scenario NB5

 

Erection

 

 

 

Scenario NB5A

141

Lorry with grab#

112

1

112.0

 

Scenario NB5B

 

048

 

Crane

 

112

1

112.0

 

*          See Table C.10, item 6 of BS 5228 for SWL

#          Lorry (CNP 141) is assumed for the purposes of the noise assessment.

 

5.3.2             Predicted Traffic Flows

 

5.3.2.1       Predicted traffic flows used in the operational noise assessment have been discussed in Section 2.8 of this report.  Transport Department have approved the traffic figures for use in the EIA and their approval is presented in Appendix G.

 

5.4                   Construction Noise Impact Assessment

 

5.4.1             Assessment Methodology

 

5.4.1.1       The assessment of the proposed alignment has comprised an evaluation of the construction noise impacts at representative sensitive receivers along its length based upon the full range of construction activity scenarios detailed above.  The construction noise at the NSRs has been assessed in accordance with the methodology of the Technical Memorandum on Noise from Construction Work Other than Percussive Piling.  The noise impact from the use of a helicopter to deliver slope stabilisation equipment has also been assessed. While the assessment of construction noise has been based upon non-restricted periods, this does not preclude the Contractor from working in restricted periods should this be required.  However, any work in restricted periods will be subject to the Contractor obtaining a valid Construction Noise Permit under the Noise Control Ordinance as detailed in Section 3.3.2.  It is likely that working up to 11.00pm will be required and further assessment of this period is presented in Section 5.4.3.12 below.

 

5.4.1.2       Potential cumulative impacts associated with the construction of the development in Tung Chung Valley are assessed in Section 12.  There are no other cumulative impacts from other contemporary projects in the vicinity.

 

5.4.1.3       Construction activities on site will involve the use of heavy machinery and as detailed in Section 5.3, an indicative schedule of key equipment to be used, activities to be carried out and duration of each segment of the works has been identified. Based upon the number and type of heavy plant to be employed in the construction works, noise levels generated will probably be high and impacts are a key issue.

 

 

 

5.4.2             Assessment Findings

 

5.4.2.1       The maximum noise levels at the NSRs during the construction phase of the alignment without noise mitigation measures applied are shown below in Tables 5.8a and 5.8b for the road earthworks and bridge works respectively, Tables 5.8c and 5.8d for the slope stabilisation and slope remediation respectively and Table 5.8e for the permanent noise barrier construction. The detailed modelling result is provide in Appendix F and a summary of the maximum unmitigated levels at each NSR is provided in Figures 5.2a to 5.2e.

 

Table 5.8a             Maximum Noise Levels (dB(A)) during Road Construction without Noise Mitigation

 

Sensitive Receiver

Slant Distance (m)

Noise Level without Mitigation, dB(A)

(EW+PC/RW)(1)

Earth Works

Retaining Wall

Pavement Construction

Scenario

E1

E2

E3

R1

R2(2)

R3

R4

P1

P2

P3

SWL

125.9

119.5

120.7

125.9

116.9

117.9

117.8

118.6

119.0

115.0

SR1

235/325

73

67

68

71

62

63

63

66

67

63

SR2

114/238

80

73

75

73

64

65

65

72

73

69

SR3

256/425

73

66

68

68

59

60

60

65

66

62

SR4

56/162

86

80

81

77

68

69

69

79

79

75

SR5

162/211

77

70

72

74

65

66

66

69

70

66

SR6

244/248

73

67

68

73

64

65

65

66

66

62

SR7

202/206

75

68

70

75

66

67

66

67

68

64

SR8

229/241

74

67

68

73

64

65

65

66

67

63

SR9

156/161

77

71

72

77

68

69

69

70

70

66

SR10

276/271

72

66

67

72

63

64

64

65

65

61

SR11

267/272

72

66

67

72

63

64

64

65

65

61

SR12

263/252

72

66

67

73

64

65

65

65

66

62

SR13

32/32

91

84

86

91

82

83

83

83

84

80

SR14

151/145

77

71

72

78

69

70

70

70

70

66

SR15

55/96

86

80

81

81

72

73

73

79

79

75

SR16

166/164

76

70

71

77

68

69

68

69

70

66

SR17

240/234

73

67

68

73

65

66

65

66

66

62

SR18

291/291

72

65

66

72

63

64

63

64

65

61

 

76

   Noise Level at the sensitive receiver exceeds relevant criteria of 75dB(A) for domestic premises

(1):              The first distance quoted relates to both earth works and pavement construction and the second distance in the column is from the NSR to the nearest retaining wall works.  Locations of retaining walls are shown in Figures 5.1a to f.

(2):              Equipment for the piling activities assumed to be noisier than that required for the detailed ground investigation.  However, based upon a worst case scenario, predicted noise levels for scenario R2 could be used to represent GI works.

 

 

 

 

 

 

 

 

Table 5.8b    Maximum Noise Levels (dB(A)) at NSRs during Bridge Construction without Noise Mitigation

 

Sensitive Receiver*

Slant Distance (m)

Noise Level without Mitigation, dB(A)

Deck Construction

Foundation Construction

Scenario

D1

D2

D3

F1

F2

F3

F4

SWL

119.8

115.5

112.0

125.9

119.1

118.0

115.5

SR9

159

71

67

63

77

70

69

67

SR10

277

66

62

58

72

65

64

62

SR11

323

65

60

57

71

64

63

60

SR12

295

65

61

58

71

65

64

61

SR13

231

67

63

60

74

67

66

63

SR14

206

68

64

61

75

68

67

64

SR15

218

68

64

60

74

67

66

64

SR16

375

63

59

56

69

63

62

59

SR17

460

62

57

54

68

61

60

57

SR18

501

61

57

53

67

60

59

57

 

 

 

 

 

 

 

 

 

76

      Noise Level at the sensitive receiver exceeds relevant criteria of 75dB(A) for domestic premises

 *                The distance between the SR1 to SR9, SR19 and the construction work is more than 500 metres, as such noise levels would not exceed the relevant noise criteria.

 

Table 5.8c    Maximum Noise Levels (dB(A)) at NSRs during Slope Stabilisation Works without Noise Mitigation

 

Sensitive Receiver

Slant Distance (m)

Noise Level without Mitigation, dB(A)

Scenario

Rock Dowelling (SS1)

Total SWL

116.3

SR1

325

61

SR2

238

64

SR3

425

59

SR4

162

67

SR5

211

65

SR6

248

63

SR7

206

65

SR8

241

64

SR9

161

67

SR10

271

63

SR11

272

63

SR12

252

63

SR13

380

60

SR14

145

68

SR15

96

72

SR16

164

67

SR17

234

64

SR18

291

62

 

76

Noise Level at the sensitive receiver exceeds relevant criteria of 75dB(A) for domestic premises.

*  Noise from transport of equipment by helicopter assessed below

         

 

 

 

Table 5.8d    Maximum Noise Levels (dB(A)) at NSRs during Slope Remediation without                                 Noise Mitigation

 

Sensitive Receiver*

Slant Distance (m)

Noise Level with Mitigation, dB(A)

Earthwork

Soil Nailing

Scenario

SR1

SR2

SWL

118.2

116.3

SR19

90

74

72

Note:     * SR1 to SR18 located near the improved Tung Chung Road, and will not affected by the slope remediation work on the obsolete section of the existing Tung Chung Road. (see Figures 2.12 and 2.13).

** Drainage works and shotcreting works associated with the slope remediation works would involve a concrete pump (CNP047) and a concrete mixer (CNP046) with a combined SWL of 109 dB(A).  Based upon the fact that no adverse impacts have been predicted for the above noisier scenarios SR1 and SR2, no impacts from the drainage works are expected.

 

Table 5.8e             Maximum Noise Levels (dB(A)) during Construction of Permanent Noise Barrier in Tung Chung Valley without Noise Mitigation

 

Sensitive Receiver

Slant Distance (m)

Noise Level without Mitigation, dB(A)

Construction of Noise Barrier

Scenario

NB1A

NB1B

NB1C

NB2

NB3

NB4A

NB4B

NB5A

NB5B

SWL

114.3

112.5

112.0

113.4

114.8

105.0

112.0

112.0

112.0

SR1A

200

63

61

61

62

64

54

61

61

61

SR1B

179

64

62

62

63

65

55

62

62

62

SR1

153

66

64

63

65

66

56

63

63

63

SR1C

149

66

64

64

65

66

57

64

64

64

SR2A

96

70

68

67

69

70

60

67

67

67

SR2B

60

74

72

71

73

74

64

71

71

71

SR2

40

77

75

75

76

78

68

75

75

75

SR2C

21

83

81

81

82

83

74

81

81

81

SR2D

25

81

80

79

80

82

72

79

79

79

SR3

242

62

60

59

61

62

52

59

59

59

SR4A

50

75

74

73

74

76

66

73

73

73

SR4

48

76

74

73

75

76

66

73

73

73

SR4B

39

77

76

75

77

78

68

75

75

75

SR4C

46

76

74

74

75

77

67

74

74

74

SR4D

25

81

80

79

80

82

72

79

79

79

SR5

168

65

63

62

64

65

55

62

62

62

Note:     * SR6 to SR19 are located more than 300 meters away from the barrier construction works and thus will not be affected by these works.

 

76

Noise Level at the sensitive receiver exceeds relevant criteria of 75dB(A) for domestic premises

 

Transportation of Slope Stabilisation Equipment by Helicopter

 

5.4.2.2       As highlighted previously, some equipment required high up the hills may need to be transported by helicopter.  The areas where the slope stabilisation works will be required are shown by the limit of slope stabilisation in the figures in Section 2.  Based upon the works, there is the potential for short term noise impacts on the local residents.

5.4.2.3       The TMEIA specifies a maximum level for helicopter noise at sensitive receivers which is 85 Lmax dB(A).  However, if the helicopter is considered to be a piece of construction equipment then the 75 dB(A) at the sensitive receivers should be met.  Thus, in order to provide a full assessment, comparison to both these standards has been made. 

 

5.4.2.4       Based upon two common helicopter types used in Hong Kong, the Lmax dB(A) of each are detailed in Table 5.9 as follows:

 

Table 5.9      Lmax dB(A) of Common Helicopter Types in Hong Kong

 

Brand

Model

Users

Reference Height (1)

Lmax dB(A) (1)

Sikorsky

S76

Government Flying Service, Private

244m (800 feet)

78dB(A)

Aerospatiale

(Eurocopter)

AS355

Private

153m (500 feet)

77dB(A)

Note (1):   Source: UK Institute of Acoustics (IOA), Volume 14, Part 4 (1992) “Noise Levels of Helicopters Performing Elevated Pad Take-off and Landing Procedures”.

 

5.4.2.5       The impact of noise from the helicopter can be calculated at the facades of the representative NSRs in terms of maximum LAmax using basic acoustic principles as follows:

 

At a specified distance, say D1, the Sound Pressure Level (Lp) should be

 

Lp(at D1) = Lw - distance attenuation (D1) ……(1)

 

where Lw is the Sound Power Level

 

Since the helicopter noise is a point source, then (1) can be converted:

 

Lp(at D1) = Lw - 20log(D1) ……(2)

 

At distance D2, then

 

Lp(at D2) = Lw - 20log (D2) ……(3)

 


Rearrange (2) and (3)

 

Lw=Lw, then,

Lp(at D1) + 20log (D1) = Lp (at D2) + 20 log(D2), and

Lp(at D2) = Lp(at D1) + 20log (D1) - 20log (D2), and

Lp(at D2) = Lp(at D1) + 20(log(D1/D2)) ……(4)

 

Equation (4) can be used to convert the reference noise level from the helicopter measurement to the noise level at a specified distance.  The facade correction factor is then included.

 

5.4.2.6       The predicted noise levels in Lmax dB(A) based on the two different helicopter types at a set of distances from noise sensitive receivers are shown in Table 5.10 below.

 

Table 5.10                Predicted Helicopter Noise (Lmax dB(A))

 

 

Distance

(metres)

 

Sikorsky S76

 

Aerospatiale AS355

 

Reference Noise Level 78

 

Reference Distance,

244 m

 

Reference Noise Level 77

 

Reference Distance,

153 m

 

Noise Level

(non-building)

 

Noise Level

(facade)

 

Noise Level (non-building)

 

Noise Level  (facade)

10

106

109

101

104

20

100

103

95

98

30

96

99

91

94

40

94

97

89

92

50

92

95

87

90

60

90

93

85

88

70

89

92

84

87

80

88

91

83

86

90

87

90

82

85

100

86

89

81

84

110

85

88

80

83

120

84

87

79

82

130

83

86

78

81

140

83

86

78

81

150

82

85

77

80

160

82

85

77

80

170

81

84

76

79

180

81

84

76

79

190

80

83

75

78

200

80

83

75

78

210

79

82

74

77

220

79

82

74

77

230

79

82

73

76

240

78

81

73

76

250

78

81

73

76

260

77

80

72

75

270

77

80

72

75

280

77

80

72

75

290

76

79

71

74

300

76

79

71

74

310

76

79

71

74

320

76

79

71

74

330

75

78

70

73

340

75

78

70

73

350

75

78

70

73

360

75

78

70

73

370

74

77

69

72

380

74

77

69

72

390

74

77

69

72

400

74

77

69

72

410

73

76

68

71

420

73

76

68

71

430

73

76

68

71

440

73

76

68

71

450

73

76

68

71

460

72

75

67

70

470

72

75

67

70

480

72

75

67

70

490

72

75

67

70

500

72

75

67

70

 

5.4.2.7       In accordance with Hong Kong’s Civil Aviation Department requirements, helicopters must operate outside a 500ft (152 metres) ceiling from residential properties.  This distance, will, therefore, be the shortest distance between the noise sensitive receivers and any helicopter noise. Based upon the results in Table 5.9, it can be seen that the maximum noise of both helicopter types would not exceed the 85dB(A) noise limit at this distance.

 

5.4.2.8       Based upon the testing and investigation, the approximate area for slope stabilisation works is shown in Section 2. The distance between slope stabilisation work and the nearest sensitive receivers is about 500 metres. According to the result shown in Table 5.10, the Lmax for the helicopter, the Sikorsky S76 and Aerospatiale AS355, is 75 and 70 dB(A) at 500m respectively which is within the 85 dB(A) criteria. The noise at the sensitive receivers is also within the 75 dB(A) noise criteria if the helicopter is considered to be a piece of construction equipment.

 

5.4.2.9       The helicopter pick-up location will be located at the proposed Contractor’s works area which is shown in Figure 2.10.  This area is 400 meters away from the nearest existing noise sensitive receivers.  Based upon this distance and the levels provided in Table 5.10 above, the maximum noise level at the closest sensitive receiver would be 77 and 72 for the Sikorsky S76 and Aerospatiale helicopters respectively.  Thus, the Sikorsky S76 helicopter would marginally exceed the noise criteria 75dB(A) if the helicopter remained on the works area for a period of 30 minutes.

 

5.4.2.10   It has been determined that in order to meet the 75 dB(A) standard, the operation of the helicopter at the pick-up location should be restricted to 60%, which equates to the helicopter operating for only 18 minutes in any half hour period at the pick-up point. This period is more than sufficient for the helicopter to remove or drop off equipment in this location and move away. In addition, the scenarios assessed are the worst case, with noise levels being lower with a quieter helicopter.

 

5.4.2.11   Thus, no unacceptable impacts are predicted from the use of the helicopter, as is the case for the slope stabilisation and slope remediation activities associated with the new road. 

5.4.2.12   However, the results detailed above for road construction, bridge construction and noise barrier construction in Tung Chung Valley indicate that, the maximum noise levels at some of the NSRs will exceed the day time noise criteria of 75dB(A). Mitigation measures are, therefore, required to reduce the noise levels to meet the standards. Recommended mitigation measures are detailed in Section 5.4.3.

 

5.4.3             Construction Mitigation Measures

 

5.4.3.1       Based upon the anticipated construction scenarios for the main alignment, the maximum noise levels at the closest NSRs would exceed the 75dB(A) noise guideline for non restricted hours at residential properties during road construction and permanent noise barrier construction.  Thus, the following noise mitigation measures should be implemented to reduce the construction noise to an acceptable level. The noise mitigation measures and the sound reduction estimated are based on current noise control technologies and BS5228 and have been confirmed by the Project Proponent as being practical.

 

5.4.3.2       Noise mitigation measures are recommended at SRs 2, 4, 5, 9, 13-16 during road construction and SR9 during bridge construction and SRs 2 and 4 in Tung Chung Valley during permanent noise barrier construction as detailed below in Tables 5.11 and 5.12 respectively.

                       

Table 5.11:     Recommended Mitigation Measures for the Noisy Equipment during Road Construction and Bridge Construction

 

Plant

Mitigation Measures*

Noise Reduction, dB(A)*

Reduction Assumed, dB(A)

·       Breaker (Excavator Mounted)

¨       Fit suitably designed muffler or sound reduction equipment.

¨       Use dampened bit to eliminate ringing

Up to 15

5

 

 

 

 

 

 

 

·       Dump Truck

·       Excavator

·       Bulldozer

·       Concrete Lorry Mixer

¨       Fit more efficient exhaust sound reduction equipment

¨       Manufacturers’ enclosure panels should be kept closed

5 to 10

5

·       Chipper

·       Poker

¨       Fit suitably designed muffler or sound reduction equipment.

¨       Ensure all leaks in air line are sealed

¨       Use dampened bit to eliminate ringing

Up to 15

5

* Reference: Noise and vibration control on construction and open sites, BS5228: Part 1: 1997, P.15-16.

 

Table 5.12      Recommended Mitigation Measures for the Noisy Equipment during Permanent Noise Barrier Construction

 

 

Plant

Mitigation Measures*

 

Noise Reduction, dB(A)*

 

Reduction Assumed, dB(A)