6.                              GROUND-BORNE NOISE

6.1                          Introduction

6.1.1.1              In this section, the requirements, methodology, equipment, monitoring locations, criteria and protocols for the monitoring and audit of ground-borne noise impacts during the construction and operation phases of the Project are presented.

6.2                          Monitoring Requirements

6.2.1.1              The ET is responsible for the provision of the monitoring equipment.  He should ensure that sufficient noise measuring equipment and associated instrumentation are available for carrying out the monitoring.  All the equipment and associated instrumentation should be clearly labelled.

6.2.2                    Noise Parameters and Criteria

6.2.2.1              The train operation ground-borne noise level should be measured in terms of the A-weighted equivalent continuous sound pressure level (Leq).  Leq(30min) should be used as the monitoring parameter.  The relevant criteria for ground-borne railway noise assessment are the limits given in Table 2 of the IND-TM based on appropriate Area Sensitivity Ratings (ASRs) at the assessment points and presented in Table 6.1.

Table 6.1       Ground-borne Operation Noise Criteria

GBNSR Description

Ground-borne Noise Criteria, dB(A)

Daytime and Evening time

(0700 to 2300 hrs)

Night-time
(2300 to 0700 hrs)

A

B

C

A

B

C

Schools – classrooms, churches/temples, libraries and courts

50

55

60

[a]

Domestic premises, hotels, hospitals and clinics,

50

55

60

40

45

50

Note:

[a]     No sensitive use during this period.

 

6.2.3                    Monitoring Equipment and Methodology

6.2.3.1              In accordance with the requirements of the Technical Memorandum (TM) issued under the NCO, sound level meters in compliance with the International Electrotechnical Commission Publications 651: 1979 (Type 1) and 804: 1985 (Type 1) specifications should be used for carrying out the noise monitoring.  Immediately prior to and following each noise measurement the accuracy of the sound level meter should be checked using an acoustic calibrator generating a known sound pressure level at a known frequency.  Measurements may be accepted as valid only if the difference between the calibration levels obtained before and after the noise measurement agree to within 1.0 dB.

6.2.3.2              Noise measurements should not be made in the presence of wind with a steady speed exceeding 5ms-1 or wind with gusts exceeding 10ms-1.  The wind speed should be checked with a portable wind speed meter capable of measuring wind speeds in m/s.

6.2.3.3              Where the train ground-borne noise is audible, but measurement of the Leq(30 min) level is not possible directly because of interference from ambient noise, particularly intermittent ambient noise, the sound exposure level (SEL) of each train movement may be measured and the Leq(30min) level obtained by calculation taking into account the SEL of each train movement within the 30-minute period.  The measurement level should comply with ASR B for both daytime and night-time criteria shown in Table 6.1.

6.2.4                    Monitoring Locations

6.2.4.1              A noise commissioning test should be conducted by the ET prior to the operation of the Project to confirm the compliance of the operational ground-borne noise levels with the NCO noise criteria.  Critical NSRs shall be monitored are summarized in Table 6.2 and depicted in Figures 6.1-6.4. 

Table 6.2       Operational Ground-borne Noise Monitoring Locations

ID No.

NSRs

Monitoring Location*

Uses

GN1

GBNSR2

New King’s Hotel

Hotel

GN2

GBNSR12

Primary School at 10-12 Wylie Road

School

GN3

GBNSR14

Shun Man House, Oi Man Estate

Residential

GN4

GBNSR26

Block R, Wing Fu Building, Whampoa Estate

Residential

GN5

GBNSR44

Yue Sun Mansion 191A Wuhu Street

Residential

Note:

*      The monitoring station should be at the lowest sensitive floor of each designated monitoring location.

 

6.2.4.2              The status and location of noise sensitive receivers may change after this manual is issued.  In such event, and if changes to the monitoring locations are considered necessary, the ET Leader should discuss with the ER and IEC to propose alternative monitoring locations and seek approval from the ER and agreement from the IEC and EPD on the proposal.  When alternative monitoring locations are proposed, the monitoring locations should be chosen based on the following criteria:

·               Monitoring within sensitive receivers close to the alignment; and

·               Avoiding disturbance to the occupants during monitoring within the sensitive receivers.

6.2.4.3              The monitoring station should be at the lowest sensitive floor of each designated monitoring location and normally be at a position 1.2m above ground inside the building structures.  If there is a problem with access to the normal monitoring position, an alternative position should be chosen, and a correction to the measurement results should be made.  The ET Leader should agree with the IEC and EPD on the monitoring position and the corrections adopted.

6.2.5                    Baseline Monitoring

6.2.5.1              Existing Leq(30min) levels should be monitored at the monitoring locations without trains running to obtain the ambient noise levels.  After the train noise levels are measured (if measured directly), these ambient levels should be deducted from the measured Leq(30min) levels to obtain the operational noise levels in the absence of ambient noise.

6.2.6                    Impact Monitoring

Construction Phase

6.2.6.1              As no construction ground borne noise impacts are anticipated to be insignificant, no construction phase ground borne noise monitoring is required.

Operational Phase

6.2.6.2              A noise commissioning test should be conducted by the ET prior to the operation of the Project to confirm the compliance of the operational ground-borne noise levels with the NCO noise criteria.  The noise commissioning test should be performed at selected key noise sensitive receivers including at least but not limited to the GBNSRs listed in Table 6.2.

6.3                          Mitigation Measures

Construction Phase

6.3.1.1              No mitigation measures are required for construction phase ground-borne noise.

6.3.1.2              MTR will further review the proposed mitigation measures for operational ground-borne noise during the construction stage after the tunnel boring.

Operational Phase

6.3.1.3              The predicted operation ground-borne noise levels complying with the NCO noise criteria, no mitigation measures are required for operation phase.