7.3 Operational Noise Assessment
Introduction
7.3.1 This section presents the methodology, sensitive receivers, relevant assessment criteria, and up to date findings on the potential operational noise impact due to Spur Line and other concurrent projects.
7.3.2 Sources of potential noise impact during operation phase of Spur Line include:
(i)
railway noise, which has three major components:
• airborne
noise originating from the propulsion system and wheel / rail interaction;
• structure
radiated or re-radiated noise resulting from wheel / rail interaction which is
transmitted through the viaduct structure; and
• noise
from the air conditioner on the top of the carriage.
(ii)
noise from fixed plant located at railway stations, such as ventilation
equipment and sewage treatment works for the station, and any standby
generators, and the proposed standby transformer located at the existing
Fanling Station electrical transformer.
Noise
Assessment Criteria
7.3.3 Railway operation noise must comply with the standards specified[1]. These include:
• maximum
A-weighted sound pressure level, Lmax at 85 dB (2300 – 0700 hours); and
• the
Acceptable Noise Levels (ANL) for the appropriate Area Sensitivity Rating (ASR)[2].
The ANLs for 07:00 to 23:00 hours and 23:00 to 07:00 hours daily are 60/65/70
and 50/55/60 dB(A) for ASRs A/B/C respectively.
7.3.4 Noise from fixed plant must be limited to:
• 5 dB(A)
below the ANL for the appropriate ASR[3],
or
• not
more than the prevailing background noise levels for quiet areas with
noise
level 5 dB(A) below the ANL.
7.3.5
In any
event, the ASR assumed in this EIA report is for indicative assessment only
given that details of the plant layout are not yet available. It should be
noted that fixed noise sources are controlled under Section 13 of the NCO. At
the time of investigation, the Noise Control Authority shall determine noise
impact from concerned fixed noise sources on the basis of prevailing
legislation and practices being in force, and taking account of contemporary
conditions / situations of adjoining land uses. Nothing in this EIA report
shall bind the Noise Control Authority in the context of law enforcement
against any fixed or construction noise sources being assessed.
7.3.6 A complete set of environmental legislation and standards related to operation noise is given in Appendix A.
Representative Noise Sensitive Receivers
7.3.7 A site survey and desk study of government survey maps and Outline Zoning Plans (OZPs) were conducted to check the existing and planned land uses of all the noise sensitive receivers within 300 m of either side of the proposed railway alignment. RNSRs were selected from these noise sensitive receivers to represent both existing and future land uses worst affected by the proposed railway development. Where NSRs are represented by high rise buildings, the floor having direct line of sight, and having the shortest distance to the noise source, was selected for noise level calculations.
7.3.8 Figure 7.1 presents the locations of these RNSRs and the proposed land use of the area based on the information of the latest OZPs published for these areas. The OZPs referenced include S/FSS/9, S/NE-KTN/4, and S/YL-ST/4. Table 7.5 gives the details of each of these RNSRs and the type of noise sensitive land use they represent.
7.3.9 Only NSRs at the above ground sections of Spur Line are considered for the railway noise assessment, as the remainder of the alignment is in tunnel (from Sheung Shui to Chau Tau). No sensitive receivers have therefore been proposed for the future New Development Area (NDA) in Kwu Tung proposed under the North East New Territories (NENT) Planning and Development Study. Noise sensitive receivers at the ground level of the Spur Line are also considered for qualitative ground borne noise assessment.
Table 7.5
Details of Representative Noise Sensitive Receivers
|
RNSR |
mPD at Ground Level |
Description of
Existing Use |
No. of Storeys of Existing
Use |
Description of Future Use
Based on OZPs and Approved Planning Applications |
Estimated No. of Storeys
of Future Use |
Area Sensitivity Ratings * |
|
1 |
+7.6 |
Low rise commercial / residential building at San Fung Avenue |
3*** |
C/R |
3 |
B |
|
2 |
+9.2 |
Choi Pik House, Choi Po Court |
30 |
R(A) |
36 |
B |
|
3 |
+9.2 |
Choi Ying House, Choi Po Court |
30 |
R(A) |
36 |
C |
|
4 |
+5.9 |
Village House |
3 |
AGR |
3 |
A |
|
14 |
+13.3 |
Village House |
3 |
OS |
3 |
A |
|
20** |
+5.3 |
Village House |
1 |
GB |
N/A |
A |
|
22 |
+5.3 |
Village House |
1 |
U |
1 |
A |
|
23 |
+4.5 |
Village House |
1 |
U |
1 |
A |
|
26 |
+3.4 |
Village House |
1 |
U |
1 |
A |
|
27 |
+3.2 |
Village House |
1 |
CA |
1 |
A |
|
28 |
+3.2 |
Village House |
1 |
CA |
1 |
A |
|
29 |
+2.9 |
Village House |
2 |
CA |
2 |
A |
Notes:
NSRs have been renumbered compared with the previous EIA (BBV 2000)
** New
NSR due to the tunnel option
* As
specified in the letter from Director of Environmental Protection dated 28 July
1999 (Ref. EP2/G/A/101).
C/R Commercial
/ Residential
R(A) Residential
Development Group A, high density, high rise
CA Conservation
Areas
U Unspecified
OS Open
Space
GB Green
Belt
N/A No
further development allowed
AGR Agriculture
*** 3
storeys dwelling on top of 3 commercial storeys
Railway
Noise
Introduction
7.3.10 This section assesses the potential impacts from the operation of Spur Line trains on sensitive receivers close to the above ground sections of the railway.
7.3.11 Noise emitted from the operation of railway on an at-grade, ballasted track is dominated by the airborne noise from the propulsion system wheel / rail interaction and the roof-mounted air conditioning (A/C) system. Trains moving on viaduct will excite vibration of the viaduct structure. This vibration is then re-radiated as noise. Trains operating on railway tracks on viaduct will therefore emit structure-radiated noise in addition to the two types of airborne noise mentioned above.
7.3.12 The noise impacts that are likely to arise from the operation of the Spur Line have been assessed using detailed prediction methodologies agreed with the Environmental Protection Department (EPD). Assessment procedures include considerations of the Technical Memorandum on Environmental Impact Assessment Process (TMEIA) and the Hong Kong Planning Standards and Guidelines (HKPSG).
Prediction
Methodology
7.3.13 For the purpose of noise assessment, the beginning of the Spur Line is taken to be the switch points of the (future) turnouts from East Rail (ER). The chainages (CH) of these switchpoints are CH 30+120 and CH 30+460 for the up and down tracks, respectively. Both tracks of the Spur Line begin on short sections of ballast through the turnouts before lowering onto tunnel to pass beneath River Sutlej. The noise assessment was carried out for all identified representative NSRs affected by the above ground sections of Spur Line track and the existing ER.
7.3.14 In terms of noise from the interaction of wheels and rails, the following factors affect the predicted noise levels:
• type of rolling stock;
• train speed; and
• type of track and rail support structures - rolling noise levels differ as trains pass over different types of track, such as jointed or continuously welded tracks as well as structures such viaducts.
7.3.15 The rail noise level at the RNSR was predicted by modeling the train as a line source. The noise level emanating from a moving train was predicted taking into account the noise attenuation due to distance, corrections for angle of view, screening effects from barriers and the facade reflection effect.
7.3.16 In predicting the noise from the railway, the track was divided into segments, the lengths of which are determined by factors such as train speed and curvature of the track. The maximum gradient of the Spur Line track at Chau Tau climbing up from the tunnel to viaduct is about 2.5%. It is therefore expected that the gradient correction for the uphill movement of the trains will be minimal.
7.3.17 Each segment is then treated as a separate line source and the noise contribution from each segment is summed to obtain the predicted noise level at the RNSR. The major wayside noise component, namely airborne noise, structure-radiated noise and A/C noise, were modeled separately and combined to obtain the predicted rail noise level.
7.3.18 Following agreement with EPD, a 20-metre segment length with the same speed was adopted in the railway noise prediction. The track centre co-ordinates for both the up and down tracks of the Spur Line which were provided by KCRC at approximately 20 m intervals, were used in the prediction model.
7.3.19 The positions of these major noise sources along the above ground sections of the alignment, namely airborne noise, structure radiated noise and A/C noise, as well as the top of the standard 1.2 m parapet wall on the viaduct were calculated from these co-ordinates. The horizontal offsets from track centers and vertical offsets from top of rails adopted in estimating the noise source locations are tabulated in Table 7.6.
Offsets adopted in
Estimating Noise Source Location
|
Noise Source |
Horizontal Offset, m |
Vertical Offset, m |
|
Outboard Plenum Gap |
1.625 |
0.98 |
|
Inboard Plenum Gap |
-1.625 |
0.98 |
|
Structure-radiated Noise (Standard Viaduct) |
0 |
-2 |
|
Structure-radiated Noise (At‑grade Plenum) |
0 |
2.08 |
|
A/C Noise |
0 |
3.74 |
|
Standard 1.2m parapet wall |
3.3 |
2.08 |
7.3.20 Appendix A7.2.a shows the speed profile of the Spur Line as provided by KCRC. The maximum speed limit along the Spur Line is 120 km/h which occurs near and in the tunnel section of the alignment. The speed profiles for the proposed alignment (both up and down tracks) provided by KCRC were used to determine the train speed for each 20 m track segment.
7.3.21 The predicted noise level at the RNSR was obtained by summing the contribution from all track segments. The railway noise calculation procedure, including equations used, together with a sample calculation, is detailed in Appendix A7.2.b.
Unmitigated
Railway Noise Levels
Baseline Railway Operation Conditions
7.3.22 To determine unmitigated noise levels, it was assumed that ballasted track would be used for the at-grade sections at Sheung Shui. Low Vibration Track (LVT) is assumed on viaducts. The first Spur Line train will depart from Sheung Shui Station at 0600 hours each day and the last train from Lok Ma Chau Terminus at 12:30 a.m.
7.3.23 The worst-case scenario in terms of railway noise assumes an ultimate train frequency of 12 trains per hour in each direction during 0700 to 2300 hours (referred to as daytime). For the restricted night time period between 2300 to 0700 hour (referred to as night time), the train frequency is assumed to be reduced to 6 trains per hour per direction.
7.3.24 The viaduct sections will be incorporated with the plenum noise reduction system, namely: a 1.2 m parapet wall above the walkway together with central plenum and noise absorption material.
Source Noise Levels
Wheel / Rail Noise
7.3.25 The train noise source term assumed in this assessment has been based on WREIA[4]. This reference (airborne) noise source level on the at grade, ballasted track section is 82.5 dB(A) in Lmax measured at 1.2 m above the ground, and at 25 m from the nearest track centreline for a 12 car transit train travelling at 130 km/h.
7.3.26 On viaduct, the airborne noise reduction provided by the multi-plenum system was based on the previous Spur Line EIA[5]. A 11 dB(A) attenuation was assumed for East Rail refurbished and unskirted trains for inboard and outboard side plenum.
7.3.27 The noise attenuation provided by the 1.2 m parapet wall was estimated based on an empirical approach developed by Maekawa[6].
7.3.28 The structure radiated noise level of the viaduct section was provided by KCRC. The structure radiated source noise level for the viaduct sections using Low Vibration Track (LVT) form is (Lmax) 66.5 dB(A) at 25 m from track centreline for a train travelling at 100 km/h. The structure radiated noise level for twin viaduct was applied for all viaduct structures along the route of the Spur Line for conservative assessment.
7.3.29 A correction of +7 dB(A) is applied to points and crossings in the rail noise assessment. Figure 7.2a and Table 7.7 show the locations of the points and crossings of Spur Line and East Rail.
Table 7.7
Location of Point and Crossing
|
Track |
Approximate
Chainage |
|
East Rail & Spur Line South Bound |
30130, 30440 |
|
East Rail North Bound |
30120, 30420 |
|
Spur Line North Bound |
30120, 30220 |
7.3.30
Noise impacts from wheel squeal will
not be generated on curves with radius of more than 250 m. As the radii of the
curvature at Chau Tau and Lok Ma Chau are 660 m and 450 m respectively, noise
impacts from wheel squeal is considered to be minor.
7.3.31 KCRC confirmed that trains used for the Spur Line have a source A/C noise level of 57 dB(A) (Lmax) at 15 m from track centreline.
7.3.32 In summary, the major railway parameters used for the railway noise assessment are shown in Table 7.8.
Table 7.8
Major Railway Parameter
|
|
Day
Time (07:00 - 23:00) |
Night
Time (23:00 - 07:00) |
||
|
East
Rail |
Spur
Line |
East
Rail |
Spur
Line |
|
|
Frequency (train/direction/hr) |
12 |
12 |
6 |
6 |
|
Train type |
Unskirted Refurbished East Rail |
Unskirted Refurbished East Rail |
Unskirted Refurbished East Rail |
Unskirted Refurbished East Rail |
|
Reference airborne noise source limit
(Lmax) (dB(A)) |
82.5 |
82.5 |
82.5 |
82.5 |
7.3.33 The unmitigated noise levels were predicted based on the WR viaduct design (central and walkway plenum, 1.2 m parapet wall) with Low Vibration Trackform (LVT). Comparison of the unmitigated noise levels in Leq (30minutes) at the RNSRs with the nighttime and daytime noise assessment criteria are given in Tables 7.9 and 7.10 respectively.
Table 7.9
|
RNSR |
Approximate Receiver Setback Distance,
m |
Unmitigated Noise Level Leq (30mins)
dB(A) between 2300 –0700 |
Noise Assessment Criteria for 2300-0700
Leq (30mins) dB(A) |
Exceedance of Acceptable Noise Level
for 2300-0700 Leq (30mins) dB(A) |
|
|
North Bound |
South Bound |
||||
|
NSR 01-1 |
60 |
55 |
63 |
55 |
8 |
|
NSR 01-2 |
60 |
55 |
62 |
55 |
7 |
|
NSR 02-1 |
100 |
105 |
59 |
55 |
4 |
|
NSR 02-2 |
100 |
105 |
58 |
55 |
3 |
|
NSR 03-1 |
150 |
155 |
59 |
60 |
0 |
|
NSR 03-2 |
150 |
155 |
58 |
60 |
0 |
|
NSR 20-1 |
55 |
50 |
44 |
50 |
0 |
|
NSR 22-1 |
60 |
55 |
50 |
50 |
0 |
|
NSR 23-1 |
65 |
60 |
51 |
50 |
1 |
|
NSR 23-2 |
70 |
65 |
50 |
50 |
0 |
|
NSR 26-1 |
65 |
60 |
51 |
50 |
1 |
|
NSR 26-2 |
65 |
60 |
50 |
50 |
0 |
|
NSR 27-1 |
50 |
45 |
49 |
50 |
0 |
|
NSR 27-2 |
50 |
45 |
52 |
50 |
2 |
|
NSR 28-1 |
60 |
60 |
48 |
50 |
0 |
|
NSR 28-2 |
60 |
60 |
50 |
50 |
0 |
|
NSR 29-1 |
100 |
100 |
47 |
50 |
0 |
Table 7.10
Comparison of the
Predicted Unmitigated Day-time (07:00-23:00)
Spur Line/East Rail Noise
Levels against Noise Criteria, dB(A)
|
RNSR |
Approximate Receiver Setback Distance,
m |
Unmitigated Noise Level Leq(30mins)
dB(A) between 0700 –2300 |
Noise Assessment Criteria for 0700-2300
Leq (30mins) dB(A) |
Exceedance of Acceptable Noise Level
for 0700-2300 Leq (30mins) dB(A) |
|
|
North Bound |
South Bound |
||||
|
NSR 01-1 |
60 |
55 |
66 |
65 |
1 |
|
NSR 01-2 |
60 |
55 |
65 |
65 |
0 |
|
NSR 02-1 |
100 |
105 |
62 |
65 |
0 |
|
NSR 02-2 |
100 |
105 |
61 |
65 |
0 |
|
NSR 03-1 |
150 |
155 |
62 |
70 |
0 |
|
NSR 03-2 |
150 |
155 |
61 |
70 |
0 |
|
NSR 20-1 |
55 |
50 |
47 |
60 |
0 |
|
NSR 22-1 |
60 |
55 |
52 |
60 |
0 |
|
NSR 23-1 |
65 |
60 |
54 |
60 |
0 |
|
NSR 23-2 |
70 |
65 |
53 |
60 |
0 |
|
NSR 26-1 |
65 |
60 |
54 |
60 |
0 |
|
NSR 26-2 |
65 |
60 |
53 |
60 |
0 |
|
NSR 27-1 |
50 |
45 |
52 |
60 |
0 |
|
NSR 27-2 |
50 |
45 |
55 |
60 |
0 |
|
NSR 28-1 |
60 |
60 |
51 |
60 |
0 |
|
NSR 28-2 |
60 |
60 |
53 |
60 |
0 |
|
NSR 29-1 |
100 |
100 |
50 |
60 |
0 |
7.3.34 Within the at-grade section at Sheung Shui, night-time criteria are exceeded at RNSRs 1 and 2, whereas daytime criteria are exceeded at NSR 1. These RNSRs are affected by the railway noise from the at-grade ballasted track section north of Sheung Shui Station. The criterion was exceeded mainly due to the higher airborne noise emitted as trains pass the points and crossings just north of the existing Sheung Shui Station.
7.3.35 On the viaduct section, predicted unmitigated noise levels at all NSRs comply with the daytime noise criteria. Night time criteria were exceeded at RNSRs 23, 26 and 27. The Area Sensitivity Rating at these RNSRs is mostly ‘A’. These RNSRs are affected by potential noise from train movements on the viaduct section. The structure radiated noise is the significant cause of noise exceedance in view of the much higher speed profile associated with the tunnel alignment than that of the viaduct alignment of the previous EIA.
7.3.36 Details of the breakdown of unmitigated noise levels for each RNSR are given in Appendix A7.2.c.
Proposed
Mitigation Measures and Residual Noise Impact
7.3.37 To mitigate the potential railway noise impact, the following mitigation is proposed:
7.3.38 To protect RNSR2 and its represented noise sensitive receivers from excessive railway noise impact, an absorptive cantilevered-typed noise barrier with a 5.8 m tall vertical panel above rail head and a 3.6 m long incline on top at 60º, 300 m in length to be erected between 30+080 and 30+380 west of the rail is proposed.
7.3.39 To protect RNSR1 and the noise sensitive receivers it represents, a vertical and absorptive noise barrier with a height of 5 m above rail head and 300 m in length is proposed between CH 30+100 and 30+400. Figure 7.2b indicates the location of the proposed barrier.
Viaduct Section
7.3.40 For the viaduct section between 35+420 and 36+700, maximum train speed limits during the night time period (23:00 - 07:00) has been proposed and is shown in Appendix A7.2d. KCRC has confirmed that the speed limits will be implemented through signalling control and/or instructions in train drivers’ manuals.
Prediction
of Mitigated Noise Level
7.3.41 With the incorporation of the above mitigation measures, the predicted mitigated noise levels predicted at all RNSRs are below their respective daytime night-time noise assessment criteria. The mitigated night time noise levels at the RNSRs are compared against their respective noise assessment criteria in Table 7.11. Detailed railway noise prediction results for all RNSRs are given in Appendix A7.2.c.
Table 7.11
|
RNSR |
Approximate
Receiver Setback Distance, m |
Proposed
Mitigation* |
Mitigated
Noise Level Leq (30mins) dB(A) between 2300-0700 |
Noise
Assessment Criteria for 2300-0700 Leq (30mins) dB(A) |
Exceedance of
Acceptable Noise Level for 2300-0700 Leq (30mins) dB(A) |
|
|
North Bound |
South Bound |
|
||||
|
NSR 01-1 |
60 |
55 |
ABS Noise
Barrier |
54 |
55 |
0 |
|
NSR 01-2 |
60 |
55 |
ABS Noise
Barrier |
54 |
55 |
0 |
|
NSR 02-1 |
100 |
105 |
ABS
Cantilevered noise barrier |
54 |
55 |
0 |
|
NSR 02-2 |
100 |
105 |
ABS
Cantilevered noise barrier |
50 |
55 |
0 |
|
NSR 23-1 |
65 |
60 |
Maximum Speed
Limits |
49 |
50 |
0 |
|
NSR 26-1 |
65 |
60 |
Maximum Speed
Limits |
50 |
50 |
0 |
|
NSR 27-2 |
50 |
45 |
Maximum Speed
Limits |
50 |
50 |
0 |
ABS =
Sound Absorptive
Provisions
for Planning Noise Sensitive Land Uses in Future
7.3.42 In view of the tunnel alignment along Kwu Tung, it is anticipated that no potential railway noise impact on the Kwu Tung North New Development Area (NDA) is anticipated. As there will be a considerable amount of development in the NDA in the future, KCRC propose to use Floating Slab Track (FST) in the tunnel section through the NDA to minimize vibration from the operating railway. In terms of chainage, FST will be approximately used at CH 32+100 to CH 33+600 (i.e. 1.5 km of track on each of the two lines).
Cumulative Impacts
7.3.43 In the tunnel alignment for Spur Line, the existing East Rail tracks must be slewed to either side of their current alignment for a short distance of the track. The future layout therefore comprises 4 tracks (2 Spur Line with up track on top of down track and 2 East Rail) for a short distance of the alignment. However, the total number of trains on the railway remains unchanged because half of the current trains simply move onto Spur Line from existing East Rail. At no time will more than 2 trains be running concurrently on this stretch of track.
7.3.44 Under these modified conditions, the significance of cumulative noise impacts from Spur Line and East Rail train operations was evaluated. The same principles were assumed in the rail noise calculation, as for the Spur Line noise assessment. As night time has the strictest noise criteria, night-time noise levels were calculated for:
• Existing East Rail noise levels.
• Cumulative noise levels from realigned East Rail and Spur Line without mitigation measures.
• Cumulative noise levels from realigned East Rail and Spur Line with mitigation measures.
7.3.45 Figure 7.2c and Table 7.12 shows the locations of the points and crossings of the prevailing East Rail.
Table 7.12
Location of Point & Crossing (Existing ER)
|
Track |
Approximate
Chainage |
|
East Rail South Bound |
30100, 30180 |
|
East Rail North Bound |
30090 |
7.3.46 These conditions were used in modeling the noise levels at selected worst case NSRs, which would be impacted to the greatest extent by East Rail and Spur Line. The prevailing noise level of the existing ER together with the unmitigated and mitigated noise levels of Spur Line and East Rail are shown in Table 7.13.
Table 7.13
Difference between Mitigated and
Unmitigated East Rail / Spur Line and Existing East Rail, dB(A)
(Night Time Period, 2300 - 0700)
|
RNSR |
Existing Rail, dB(A) |
(a) Unmitigated Noise Levels of Spur Line
dB(A) |
(b) Unmitigated Noise Levels of East Rail
dB(A) |
(c) Cumulative Unmitigated Levels of Spur
Line / East Rail dB(A) |
Difference between Unmitigated East Rail
/ Spur Line and Existing Rail, dB(A) |
(d) Mitigated Noise Levels of Spur Line
dB(A) |
(e) Mitigated Noise Levels of East Rail
dB(A) |
(f) Cumulative Mitigated Levels of Spur
Line/ East Rail dB(A) |
Difference between Mitigated East Rail /
Spur Line and Existing East Rail, dB(A) |
|
01-1 |
62 |
60 |
60 |
63 |
1 |
49 |
52 |
54 |
-8 |
|
01-2 |
61 |
59 |
59 |
62 |
1 |
50 |
52 |
54 |
-7 |
|
02-1 |
60 |
56 |
56 |
59 |
-1 |
50 |
51 |
54 |
-6 |
|
02-2 |
59 |
55 |
54 |
58 |
-1 |
46 |
47 |
50 |
-9 |
Note:
Noise levels (c) and (d) are the cumulative
noise levels from the Spur Line and East Rail.
(c) = 10*log(10^((a)/10)+10^((b)/10))
(f) = 10*log(10^((d)/10)+10^((e)/10))
7.3.47 Table 7.13 shows that the cumulative noise levels are only slightly different from that of the existing East Rail because the same total number of trains will be operated on the current East Rail with half of the trains simply being directed onto Spur Line. As a result of the mitigation for Spur Line, there is a considerable improvement in the cumulative unmitigated noise levels of the Spur Line / East Rail compared with existing East Rail.
7.3.48 The existing East Rail operation noise level is much higher than the noise level achieved for the mitigated Spur Line operation. A decrease in noise for the cumulative operation of mitigated Spur Line and East Rail is at least 6 dB(A) at all NSRs.
7.3.49 In summary, the implementation of mitigation under the Spur Line scheme has a positive effect on reducing noise levels for the existing East Rail train operation and the maximum mitigation has been incorporated in the Spur Line design to minimize cumulative impacts.
Interim Period
7.3.50 During the construction of the Spur Line, the existing East Rail is temporarily diverted such that the two existing tracks will be slightly closer to NSR 1. Figure 7.2d shows the interim alignment of East Rail. Figure 7.2e and Table 7.14 show the locations of the points and crossings of the interim East Rail.
Table 7.14
Points and Crossings of Interim ER
|
Track |
Approximate
Chainage |
|
East Rail South Bound |
31050 |
|
East Rail North Bound |
31000 |
7.3.51 The interim railway noise assessment has been undertaken based on the existing ER operational mode and the findings are shown in Table 7.15. Although Table 15 shows that the railway noise impact on NSR 1 is predicted to exceed the night time noise criterion during the interim period, comparison between Table 7.13 and Table 7.15 shows that the noise levels associated with the interim East Rail is slightly lower than that of existing Eat Rail. This is due to the relocation of the point and crossing of the existing East Rail further north of NSR2. .
Table 7.15
|
RNSR |
Interim East Rail, dB(A) |
Night Time Railway Noise Criteria, dB(A) |
Exceedance of Night Time Railway Noise
Criteria, dB(A) |
|
01-1 |
61 |
55 |
6 |
|
01-2 |
60 |
55 |
5 |
|
02-1 |
58 |
55 |
3 |
|
02-2 |
56 |
55 |
1 |
Ground Borne Noise and
Vibration during Railway Operation
7.3.52 To ensure that there will be no impact caused by ground borne noise and vibration during the operation of the railway, Floating Slab Track is to be incorporated into the tunnels wherever there is existing or potential for future development along the alignment. The design criterion determined by KCRC as being appropriate for ground borne noise is NR30, which is more stringent than the Noise Control Ordinance.
Summary
7.3.53 Based on noise levels of East Rail refurbished trains, ultimate railway operation frequency, ballasted track for at grade section and LVT for viaduct section, unmitigated noise levels due to the railway operation of the Spur Line were predicted for each RNSR. For the at grade section, wheel / rail noise together with noise due to the crossovers are the main components of potential airborne noise.
7.3.54 For the viaduct section, the structural borne noise is the major noise contributor due to the proximity of the low rise RNSRs to the alignment.
7.3.55 The night-time noise assessment criterion was exceeded at some of these RNSRs due to their location close to the railway alignment, and the predominance of a rural or semi-rural environment in the Study Area, which leads to an ASR associated with the most stringent noise criteria for railway noise.
7.3.56 To mitigate the potential railway operation noise to an acceptable level, the following mitigation measures are proposed:
• Absorptive vertical noise barrier and absorptive cantilever noise barrier over turnouts just north of the Sheung Shui Station is proposed to mitigate the airborne noise at the medium rise noise sensitive receivers represented by RNSR 1 and RNSR 2 near Sheung Shui Station.
• Maximum speed limit will be applied at the viaduct section during the night time period (2300 to 0700).
• A viaduct design similar to that adopted for West Rail with a parapet extending to 1.2 m above the safety walkway together with median walls will be adopted on all viaduct sections.
7.3.57 Following the implementation of the above mitigation measures the residual noise at RNSRs will meet both the daytime and nighttime noise assessment criteria.
7.3.58 In view of the tunnel alignment, no railway noise impact on Kwu Tung North NDA is expected.
7.3.59 Cumulative impacts from Spur Line and the existing East Rail were evaluated to examine the relative impact from each rail operation. The existing East Rail operation has a relatively lower noise level than that arising from Spur Line operation. Mitigation that has been incorporated into the Spur Line design minimizes the impact from Spur Line on cumulative noise levels, and also has the positive effect of reducing noise levels from the existing East Rail operation.
Fixed
Plant Operation Noise
7.3.60 The fixed noise sources of the Spur Line during operation phrase include the following equipment:
•
Ventilation fans, dosing pumps, sewage pumps and motors from the
proposed Sewage Treatment Works (STW) for the Lok Ma Chau Station.
•
Ventilation fans, transformers, air handling units, emergency
generators and chillers of the Lok Ma Chau Station.
•
Ventilation fans, transformers at the east and west and the Kwu Tung
Station ventilation buildings.
7.3.61 The treatment process of the STW at Lo Wu is expected to be similar to that proposed at the Lok Ma Chau Station, although the capacity of the STW at Lo Wu is greater than that of the one planned at Lok Ma Chau.
7.3.62 Due to the long distance (over 500 m) from any noise sensitive receivers, the equipment located at the Lok Ma Chau Terminus is unlikely to cause any potential impact. On the other hand, noise from the equipment housed in the west and east ventilation buildings and the ventilation building for the Kwu Tung Station has to be considered as a design constraint to minimize any potential impact on nearby sensitive receivers.
7.3.63 Table 7.16 gives the estimated design noise limits based on acoustic principles with reference to Table 5 of TM2. These limits should be included as part of the design and purchasing contract to meet the operation noise assessment criteria.
7.3.64 3 dB(A) has been subtracted from the design noise limits to account for the façade reflection effect at the receiver. Another 5 dB(A) was subtracted from the design noise limits to meet requirements under TMEIAO. The locations of various ventilation buildings are shown in Figure 7.1.
Table 7.16
Overall Design Noise Limits at
of Ventilation Buildings, dB(A)
|
|
Nearest RNSR |
Intervening Distance, m |
Distance Correction, dB |
Proposed Area Sensitivity Rating |
NCO limit at Receiver Limit, dB(A) |
Overall Design Noise Limits at
ventilation buildings dB(A) |
|
East Ventilation Building |
4 |
300 |
57.5 |
A |
50 |
100 |
|
West Ventilation Building |
20 |
70 |
44.9 |
A |
50 |
87 |
|
Kwu Tung Station Ventilation Building |
14 |
120 |
49.6 |
A |
50 |
92 |
Notes:
1.
3
dB(A) was subtracted from design limit to allow for façade correction at
receiver.
2.
5
dB(A) was subtracted from design limit to meet requirements under TMEIAO
(Acceptable Noise Levels under Noise Control Ordinance - 5 dB)
3.
The
more stringent NCO noise limits for 1900 to 0700 are used to calculate the
design noise limits for worst case approach.
4.
These
design noise limits should be imposed at any doors, louvers, openings, windows
at the two respective ventilation buildings, in order to comply with Noise
Control Ordinance.
5.
Although
RNSR9 is closest to the proposed Kwu Tung Station Ventilation Building, the
fact that it is a kindergarten means that it is not subject to the night time
NCO limit, and is therefore not the worst case scenario for the design of this
building. RNSR14, at 20 m further from the building than RNSR9, was used in
this assessment.
7.3.65 In addition to the design noise limits the following considerations should be given to the layout of the buildings which house the potential noisy equipment:
•
For east
ventilation building, any doors, louvers, openings, windows should be placed on
the east or north sides of the building, the south and west sides should be
left as a bank façade if possible.
•
For west
ventilation building, any doors, louvers, openings, windows should be placed on
the west or south sides of the buildings. North and east sides of the buildings
should be enclosed as far as practicable.
7.3.66
These will prevent
noise being emitted towards
the potential noise sensitive receivers.
EVA for Lok Ma Chau Station
7.3.67 The widening of Lok Ma Chau Road is to facilitate emergency access (EVA) and to service Lok Ma Chau Station. The station itself is in the Closed Border Area and no public access will occur. It is expected that the future traffic projection on this road is so small that the potential road traffic noise impact to nearby villages is considered to be minor.
7.4
Conclusions
Construction Noise
7.4.1
Unmitigated construction noise
activities associated with the Spur Line would cause exceedances of the daytime
construction noise criterion at most of the nearby sensitive receivers during
normal working hours. In addition to the good site practice, use of mitigation
measures such as hoarding modified as temporary cantilever type noise barrier,
on-site movable noise barrier, quiet plant and limiting the number of plant
operating concurrently have been recommended. With the implementation of these
measures, compliance with the construction noise criterion is expected. Regular
monitoring of noise will be required during the construction phase and has been
presented in a separate EM&A Manual.
Operational Noise
7.4.2
The railway noise assessment criterion
was predicted to be exceeded at some of the NSRs due to their location close to
the railway alignment and the turnouts. Mitigation measures in terms of noise
barrier, cantilever noise barrier and reduction of speed during night time has
been recommended in order to ensure compliance with noise criterion.
7.4.3 The recommended specification of the West and East Ventilation Buildings and the ventilation shaft in the Kwu Tung Station should ensure no exceedances of the EIAO-TM noise criteria at the nearby NSRs.
[1] Annex 5, Table 1, Technical Memorandum of Environmental Impact Assessment Process, 1997, Environmental Protection Department, Hong Kong Government.
[2] Table 3, Technical Memorandum for the Assessment of Noise from Places other than Domestic Premises, Public Places or Construction Sites, 2nd Edition, Environmental Protection Department, June 1997, Hong Kong Government.
[3] Table 3, Technical Memorandum for the Assessment of Noise from Places other than Domestic Premises, Public Places or Construction Sites, 2nd Edition, Environmental Protection Department, June 1997, Hong Kong Government.
[4] Marsden P.R., Pyke J.R. and Bullen R. West Rail EIA Final Report (1998). ERM HK Ltd for
KCRC
[5] BBVHKL for KCRC ERE, Sheung Shui to Lok Ma Chau Spur Line Environmental Impact Assessment, 2000
[6] Leo L. Beranek, Noise and Vibration Control, pp. 174-180, McGraw-Hill, 1988
