1                     INTRODUCTION

Background Information

1.1               This is the first bimonthly Operational Phase Traffic Noise Monitoring Report prepared by Maunsell Environmental Management Consultants Ltd. (MEMCL), the designated Environmental Team (ET), for the Project “Widening of Yuen Long Highway Between Tan Kwai Tsuen and Shap Pat Heung Interchange”.  This report presents the results of operational traffic noise level at noise sensitive receivers (NSRs) identified in the Traffic Noise Monitoring Plan. The objective of this report is to assess whether the level of traffic noise measured at the designated NSRs are environmental compliance after the mitigation measures (noise barrier) was implemented.

1.2               In accordance with the “Final Environmental Impact Assessment Report for Preliminary Design and Ground Investigation for Widening of Yuen Long Highway between Lam Tei and Shap Pat Heung Interchange”, in order to assess the effectiveness of the proposed barriers, traffic noise monitoring is required to be carried out at representative NSRs within one year of the road opening. A Traffic Noise Monitoring Plan (Version No.1) was prepared based on the requirement stipulated in the Environmental Permit No.EP-141/2002 Clause 5.1 and was submitted to EPD by ER.

1.3               Pre-monitoring joint site inspection was carried out on 30 August 2006 by the Engineer Representative (ER), the Contractor and ET to determine the exact location of stations for the monitoring.  

1.4               In accordance with the Traffic Noise Monitoring Plan, the noise measurements will be conducted at 11 designated monitoring locations as shown in Figure 1.1. The objectives of the measurements were to obtain sound pressure levels (SPL), in L10 (1-hour), as measured at the sensitive receivers during the peak traffic periods of a day and check if they complied with specified noise standard.

1.5               In addition to the SPL measurement, relevant information, including traffic counts, speed checks, weather conditions, activities which might generate extraneous noises were also recorded.

1.6               This Report presents the traffic noise results and observations of traffic noise monitoring in the bimonthly period from 1 August to 30 September 2006 just after construction phase EM&A programme ceased on 31 July 2006.


2                     MEASUREMENT METHODOLOGY

Measurement Time

2.1               Traffic noise measurements were conducted on normal weekdays during the AM peak traffic hour from 08:00 to 09:00.   

Noise Monitoring Locations (Noise Sensitive Receivers)

2.2               Noise measurements were conducted at eleven designated monitoring locations according to the Traffic Noise Monitoring Plan which was shown in Figure 1.1. Table 2.1 describes these monitoring stations.

2.3               During the pre-monitoring joint site inspection carried out on 30 August 2006. Some occupants rejected us using their premises for monitoring and some premises were unoccupied. Traffic noise monitoring was thus carried out at alternative locations. Essentially, the alternative of monitoring locations were on the same premise but at different floor or the location which was adjacent to the proposed location in regard of reflecting the traffic noise impact on the residents.

Table 2.1          Noise Monitoring Locations (Sensitive Receivers)

NSR ID*

Monitoring Station

Monitoring Station Location

Predicted Noise Level (mitigated), L10 dB(A) in Year 2021^

Noise Standard

L10

(peak hour) (dB(A))

93

M1

Village House in Tan Kwai Tsuen (1/F)**

65

70

17

M2

Village House near Great Garden (1/F)**

66

 

M3

Village House in Tai Tao Village (1/F)***

68 !

 

M4

Village House beside Tong Tai Road (1/F)***

64 @

13

M5

Jasper Court Block 10 (4/F)

70

24

M6

Village House in Lam Hau Tsuen (1/F) **

66

88

M7

Village House in Lam Hau Tsuen (1/F)**

61

 

M8

Village House beside Kung Um Road (1/F) ***

64 #

 

M9

Sham Chung Tusen (3/F)***

69 %

 

M10

Shung Ching San Tsuen (1/F)***

65 +

26

M11

Village House near Kung Um Road (3/F)

70

*       Noise Sensitive Receiver (NSR) ID number used in the Final EIA Report.

**     Monitoring location was allocated to different floor.

***    Monitoring location was allocated to another premise nearby.

!       Predicted noise level was obtained from NSR ID 57.

@    Predicted noise level was obtained from NSR ID 20.

#       Predicted noise level was obtained from NSR ID 79.

%     Predicted noise level was obtained from NSR ID 31.

+      Predicted noise level was obtained from NSR ID 65.

^      Various types of noise barriers were built as mitigation measures.

 

 

           


Noise Monitoring Equipment

2.4               The Sound Level Meters to be used for the monitoring will comply with the International Electrotechnical Commission Publications 651:1979 (Type 1) and 804:1985 (Type 1). Any other noise measuring and analysis instrument used will be of comparable professional quality. The instrumentation to be used for the noise monitoring is given Table 2-2.

Table 2.2          Traffic Noise Monitoring Equipment

Manufacturer

Description

Integrating Sound Level Meter

B&K 2238

Calibrator

B&K 4231

 

Maintenance and Calibration

2.5               The sound level meter will be calibrated using a Bruel and Kjaer Sound Level Calibrator Type 4231 for 94dB at 1kHz, prior to and after each set of measurements. The results of the calibration will be recorded on the field data sheet.  Measurement results will be discarded if the calibration before and after does not agree to within 1dB(A) and measurement will be taken until this condition is fulfilled.

Noise Measurement Methodology

2.6               The noise measurements were conducted to obtain one set of A-weighted L10 (1 hour) sound pressure level during the AM peak traffic hour in one-hour monitoring period at each designated sensitive receiver.  

2.7               The noise measurement point was at a point 1m from the exterior of the sensitive receiver building facades and was at a position at least 1.2m above ground of the sensitive receiver level.

2.8               Noise measurements were made in accordance with Section III of the “Calculation of Road Traffic Noise (CRTN), 1998”.

2.9              As recommended in CRTN, a façade effect correction factor of 2.5 dB(A) will be further added to the measured noise level if the monitoring is carried out in a free field condition.

2.10            Statistical results such as Lmax, Lmin, Leq and L90 were also obtained for reference purpose.

2.11            The wind speed was frequently checked with a portable wind meter.

2.12            Observations were recorded when intrusive noise was unavoidable.

2.13            Noise monitoring was cancelled in the presence of fog, rain, wind with a steady speed exceeding 5 m/s, or wind with gusts exceeding 10 m/s.


Traffic Survey

2.14            Traffic surveys were conducted concurrently with the noise measurement for the sections of Yuen Long Highway in front of the representative sensitive receivers.

2.15            Background information, including weather conditions and noise sources other than traffic along Yuen Long Highway, was recorded at each sensitive receiver.  The traffic survey included monitoring of traffic flow, percentage of heavy and light vehicles and average traffic speed.

2.16            Since there were slip roads dividing the highway into three sections with different traffic conditions, traffic surveys were conducted for three sections separately.

2.17            Details of the noise measurement and traffic survey locations as well as relevant activities are presented in Table 2.3.

Table 2.3          Details of the Noise Measurement and Traffic Survey locations

Monitoring Station

Monitoring Station Location

Type of Measurement

Nature

Activities

M1

Village House in Tan Kwai Tsuen (1/F)

Façade

 

 

Noise Sensitive Receiver

Ÿ         Noise measurement

Ÿ         Recording of noise sources other than traffic along Yuen Long Highway

M2

Village House near Great Garden (1/F)

M3

Village House in Tai Tao Village (1/F)

Free Field

 

M4

Village House beside Tong Tai Road (1/F)

Façade

 

M5

Jasper Court Block 10 (4/F)

M6

Village House in Lam Hau Tsuen (1/F)

M7

Village House in Lam Hau Tsuen (1/F)

M8

Village House beside Kung Um Road (1/F)

M9

Sham Chung Tusen

(3/F)

M10

Shung Ching San Tsuen (1/F)

M11

Village House near Kung Um Road (3/F)

M3

Hill, near monitoring station for M1 - M3

Not Applicable

Traffic Survey Location

Ÿ         Traffic flow survey

Ÿ         Traffic speed measurement

Ÿ         Percentage of heavy vehicles

M5

Roof, Jasper Court Block 10 for M4 - M7

M9

Roof, House 96, Shum Chung Tsuen for M8 - M11

 


3                     MEASUREMENT RESULTS AND OBSERVATIONS

General

3.1               During the course of noise monitoring, road traffic along Yuen Long Highway was the major noise source. Noise data was continuously recorded by sound level meter at an interval of 1 second. Other sources included community noise, dog barking, wigwag system and sirens from emergency vehicles, traffic on the local road, nearby construction activities, and etc. These activities were recorded during the monitoring events and these extraneous noises were not taken into calculation of the traffic noise level.

Traffic Noise Level Monitoring Results

3.2               Traffic noise measurements were conducted on three weekdays during the AM peak traffic hour from 08:00 – 09:00 of 5, 6 and 7 September 2006. Random check of wind speed at the monitoring station showed that it was below 5 m/s.

3.3               There were some activities, which generated extraneous noises, and these activities were recorded during the monitoring events. The noise data was recorded by the sound level meter. Based on the site records, non-traffic related data was neglected, in order to indicate the traffic noise level of Yuen Long Highway.

3.4               The summaries of traffic noise levels recorded are provided in Table 3.1.

Table 3.1          Traffic Noise Measurement Results

Monitoring Date

Weather Condition

Monitoring Station

Monitoring Period

Noise Level (mitigated), L10 dB(A)

5 September 2006

Sunny

M1

8:00 – 9:00

61.0

M2

8:00 – 9:00

59.0

M3

8:00 – 9:00

62.0

6 September 2006

Fine

M4

8:00 – 9:00

64.0

M5

8:00 - 8:10:34*

65.5

8:00 – 9:00 **

77.5

M6

8:00 – 9:00

58.5

M7

8:00 – 9:00*

60.0

8:00 – 9:00**

65.0

7 September 2006

Cloudy

M8

8:00 – 9:00

60.5

M9

8:00 – 9:00

64.5

M10

8:00 – 9:00

70.5

M11

8:00 – 9:00

63.5

Note:

*  Time period with construction noise data erased.

** Time period with nearby construction activities included.

 


3.5               Comparison of the edited noise measurement results was made against the noise standard of 70 dB(A). Tables 3.2 showed that measurement in L10 at the monitoring stations in comparison with the noise standard.

Table 3.2          Noise Level Comparison with the Noise Standard

Monitoring Station

Monitoring Period

Noise Level (mitigated), L10 dB(A)

Noise Standard

L10 (1 hour) dB(A)

M1

8:00 – 9:00

61.0

70

M2

8:00 – 9:00

59.0

M3

8:00 – 9:00

62.0

M4

8:00 – 9:00

64.0

M5

8:00 - 8:10:34*

65.5

8:00 – 9:00**

77.5

M6

8:00 – 9:00

58.5

M7

8:00 – 9:00*

60.0

8:00 – 9:00**

65.0

M8

8:00 – 9:00

60.5

M9

8:00 – 9:00

64.5

M10

8:00 – 9:00

70.5

M11

8:00 – 9:00

63.5

Note:

*  Time period with construction noise data erased.

** Time period with nearby construction activities included.


Road Condition and Traffic Survey

3.6               As noted during the course of monitoring, the road surfaces of Yuen Long Highway were asphalt paved. No obstruction or damage was noted from the road surfaces.

3.7               The traffic conditions along Yuen Long Highway were normal and there was no traffic congestion during the monitoring periods.

3.8               The percentage of heavy vehicle (HV) was significantly higher than that of light vehicle (LV). Details of the traffic flow and the percentage of heavy vehicle are provided in Table 3.3.

Table 3.3          Traffic Flow of Yuen Long Highway

Monitoring Station

LV

HV

Total Flow

Percentage of HV

M1

2288

2784

5072

54.9

M2

2288

2784

5072

54.9

M3

2288

2784

5072

54.9

M4

2436

3004

5440

55.2

M5

2116

2684

4800

55.9

M6

1668

2560

4228

60.5

M7

1668

2560

4228

60.5

M8

2276

2972

5248

56.6

M9

2276

2972

5248

56.6

M10

2276

2972

5248

56.6

M11

2276

2972

5248

56.6

Notes:

HV represents Heavy Vehicle

LV represents Light Vehicle

 

3.9               The traffic speeds along Yuen Long Highway were estimated concurrently with the noise measurement. Table 3.4 provides a summary of averaged traffic speed monitoring results.

Table 3.4          Traffic Speed Measurement

Monitoring Station

Speed (km/hr)

M1

80.09

M2

80.09

M3

80.09

M4

73.72

M5

73.72

M6

73.72

M7

73.72

M8

81.26

M9

81.26

M10

81.26

M11

81.26

 


4                     DISCUSSION

4.1               As shown in Table 3.2, in the monitoring station at M5, noise measurement at station M5 was significantly interrupted by construction noise in the vicinity of the monitoring location from 08:10:35 – 09:00.  There was insufficient time to measure one L10 (1 hr) at this AM peak traffic flow period. The noise level without construction activity was 65.5 dB(A); i.e. below the noise standard of 70 dB(A). The results indicated the noise level in which the construction activities included was exceeded with the noise standard by 7.5 dB(A).

4.2               The noise level recorded at M10 exceeded with the noise standard by 0.5 dB(A).

4.3               The noise levels recorded at the remaining nine monitoring stations were below the noise standard in this reporting period.   In the monitoring station at M7, noise measurement at station M7 was significantly interrupted by construction noise in the vicinity of the monitoring location.  There was insufficient time to measure one L10 (1 hr) at this AM peak traffic flow period. The results indicated the noise level with and without construction activity were below the noise standard.

Predicted Noise Levels under the Traffic Flow Condition in 2021

4.4               The following equation extracted from the CRTN was adopted to correct the measured noise level in consideration of the differences between the measured traffic flow and the predicted traffic flow in the Final EIA Report.

* Correction Factor = 

 

Where   Q’ is predicted traffic flow by using the CRTN noise model,

V’ is predicted traffic speed by using the CRTN noise model,

p’ is predicted percentage heavy vehicle by using the CRTN noise model,

Q is measured traffic flow during the traffic noise monitoring event,

V is measured traffic speed during the traffic noise monitoring event,

p is measured percentage heavy vehicle during the traffic noise monitoring event.

 

4.5               According to the Environmental Impact Assessment Final Report for the Project, “Agreement No. CE 98/98 - Preliminary Design and Ground Investigation for Widening of Yuen Long Highway Between Lam Tei and Shap Pat Heung Interchange”, for the worst case scenario, the traffic noise levels was predicted to occur in year 2021.

4.6               Slip road segment was in front of M5 with different traffic flow and speed when comparing with those at Yuen Long Highway.  Therefore, the correction factor evaluation method could not be applied for the measured noise level at M5. Nonetheless, the measured traffic noise levels, with treated data were directly compared with the noise standard of 70 dB(A).

4.7               Detailed traffic conditions in year 2021 are summarized in the Table 4.1.

Table 4.1          Predicted 2021 Peak Hour Traffic Data

Noise Monitoring Location

Traffic Flow (Nr/hr)

% of HV

Traffic Speed (km/hr)

M1 – M4, M6 – M11

10,900

53

80

 

 

4.8               The correction factors for each monitoring period were evaluated and summarized in Table 4.2.

Table 4.2          Correction Factor for Different Monitoring Period

Sensitive Receiver

Correction Factor dB(A)

M1

3.2

M2

3.2

M3

3.2

M4

3.2

M6

3.7

M7

4.0

M8

4.0

M9

2.8

M10

2.8

M11

2.8

 

4.9               Under the designed traffic condition in 2021, the predicted noise levels as received at the sensitive receivers, M1 – M4, M6 – M11 are estimated and shown in Table 4.3.

Table 4.3          Measured and Corrected Noise Level

Sensitive Receiver

Measured Noise Level, L10 dB(A)

Corrected Noise Level, L10 dB(A)*

Predicted Noise Level (mitigated), L10 dB(A) in Year 2021*

M1

61.0

64.2

65

M2

59.0

62.2

66

M3

62.0

65.2

68

M4

64.0

67.2

64

M6

58.5

62.5

66

M7

60.0 **

64.0

61

65.0 ***

69.0

M8

60.5

63.3

64

M9

64.5

67.3

69

M10

70.5

73.3

65

M11

63.5

66.3

70

                Note

*   Corrected by traffic flow, speed and percentage of heavy vehicles.

**  Time period with construction noise data erased.

*** Time period with nearby construction activities included.

                                   

 


5                     CONCLUSION

5.1               Traffic noise measurements were conducted on three weekdays during the AM peak traffic hour from 08:00 to 09:00 of 5, 6 and 7 September 2006. The weather conditions were sunny, fine or cloudy respectively.  The traffic conditions, including traffic flows, type of vehicles and average traffic speeds were also monitored during the monitoring events.

5.2               Activities which generated extraneous noise were recorded, and these irrelevant noise data were not taken into the evaluation of traffic noise levels.

5.3               Sound pressure levels, in L10 (1hr), were recorded at the 11 designated monitoring locations. Results indicated that all measurement L10 (1 hour) levels were below the noise standard of 70 dB(A) except the monitoring locations at M5 (which was due to the construction noise in the vicinity) and M10.

5.4               The traffic flow, speed and percentage of heavy vehicles were recorded during each monitoring period.  The correction factors for M1 – M4 and M6 – 11 were evaluated based on the differences of traffic conditions between these noise measurement events and the predicted traffic condition in year 2021. The corrected noise levels were also compared with the predicted noise levels.

5.5               All corrected noise levels for the ten monitoring locations in the year 2021 did not exceed  the noise standard of 70 dB(A) under the predicted traffic condition in 2021 except for monitoring location at M10 after applying the appropriate correction factor.


6                     REFERENCES

1.                   Department of Transport, UK (1988), Calculation of Road Traffic Noise

 

2.                   Scott Wilson (Hong Kong) Ltd. (2001), Agreement No. CE 98/98 - Preliminary Design and Ground Investigation for Widening of Yuen Long Highway Between Lam Tei and Shap Pat Heung Interchange - Environmental Impact Assessment Final Report