Appendix 5.13.4 Helicopter Noise Measurement Methodology

Introduction

This technical note is to present the noise measurement methodology for helicopters operated at Macau Ferry Terminal Helipad.

Measurement Methodology

Integrating Sound Level Meters were ill beas used for helicopter (Sikorsky 76C+) noise monitoring at the existing MFT Helipad. The equipment willwas complyied with International Electrotechnical Commission Publications 651:1979 (Type 1) and 804:1985 (Type 1). Table 1 summarises the noise monitoring equipment model to be used during measurement.

Table 1 Noise Monitoring Equipment

Equipment	Model
Integrating Sound Level Meter	B&K Brand Type 2238
Calibrator	B&K Brand Type 4231
Portable Wind Speed Meter	Davis Instruments

Monitoring Locations

The worst affected sensitive receivers arising from helicopter operation at MFT Building wereas identified according to the findings of the site visit and were proposed as monitoring locations. Based on the existing information, Tthree sensitive facades were identified as monitoring stations are selected from the identified noise sensitive receivers for noise measurement. If access was not allowed or noise monitoring was found not practical to be carried out at these sensitive receivers, the measurement would be conducted at alternative monitoring locations, such as rooftop of the identified sensitive building or alternative locations adjacent to the selected buildings, as the back-up monitoring points. The alternative monitoring points would be selected with similar nature as the sensitive receivers in terms of height of building, angle of view and the similar surrounding environment. Appropriate correction of noise impact at the worst affected receivers would be applied if other points are adopted for noise measurements.

As the monitoring stations are partially screened by Shun Tak Centre and mode of operation cannot bye clearly observed, a reference monitoring location at the rooftop of Shun Tak Centre Carpark (which is at a similar level to the existing MFT Helipad) iwas selected. Alternative monitoring locations adjacent to the selected buildings will be considered as the back up monitoring points, in case noise monitoring is found not practical to be carried out at the sensitive receivers. The alternative monitoring points will be selected with similar nature as the sensitive receivers in terms of height of building, angle of view and the similar surrounding environment.

Details of the noise monitoring locations are summarized in Table 2 while Figures A3.1 and 2 shows the locations of proposed monitoring locations and alternative monitoring locations. The whole operation mode including Approach, Hovering, Idling and Take- Ooff of the helicopters willere be recorded at the reference point. All noise monitoring locations wereill beas set at a point 1m from the exterior of the sensitive receiver façade of the following buildings so as to include the façade effect.

Table 2 Noise Monitoring Locations

Proposed Monitoring Locations	Alternative Measurement Location	RemarksSelected Monitoring Location for Measurement
The Bauhinia (Korea Centre) – affected receiver / rooftop (NSR N5)	Harbour Commercial Building (Monitoring Point A5) An alternative location next to the Bauhinia and have similar angle to MFT Helipad and screening effect from Shun Tak Centre	Roof of Harbour Commercial Building (Not allowed by the property management office to conduct the noise measurement at Bauhinia) Alternative location next to the Bauhinia and have similar angle to MFT Helipad and screening effect from Shun Tak Centre
Ka On Building – affected receiver / rooftop (NSR N6)	Soonvar House (Monitoring Point A6) Alternative location next to the Ka On Building and have similar angle to MFT Helipad and screening effect from Shun Tak Centre	Roof of Alternative location next to the Ka On Building and have similar angle to MFT Helipad and screening effect from Shun Tak CentreKai On Building
Talon Tower- affected receiver / rooftop (NSR N6a)	B2BWayson Commercial Building Centre (Monitoring Point A6a) Alternative location next to the Talon Tower and have similar angle to MFT Helipad and screening effect from Shun Tak Centre	Roof of Wayson Commercial Building (Not allowed by the property management office to conduct the noise measurement at Talon Tower)Alternative location next to the Talon Tower and have similar angle to MFT Helipad and screening effect from Shun Tak Centre
Reference Monitoring Location	Alternative Reference Measurement Location	Selected Monitoring Location for MeasurementRemarks
Shun Tak Centre Carpark -– rooftop (R1)	China Merchants Tower (level to be similar to the level of helipad) (Reference Point2) Alternative location next to the Carpark and have direct line of sight to the helipad	Rooftop of Shun Tak Centre CarparkAlternative location next to the Carpark and have direct line of sight to the helipad

Monitoring Parameters, Frequency and Duration

The sound pressure level, Due to the limitation of the monitoring equipment, L_Aeq(0.1s) , will beas continuously recorded over a period of 11 hour which will covered different modes of operations of helicopters including Approach, Hovering, Idling and Take Off. Sample log sheets are attached. The relevant noise level of all operation models in terms of other noise parameters such as maximum noise levels (L_max), etc was also recorded.

During the monitoring, the following information will beas recorded by using the attachedin the log sheets:

At Shun Tak Centre (Reference Location)

· Number of flights;

· Time and Duration of different modes of operations of helicopters (Approach, Hovering, Idling and Take Off);

· Flight path (Approach and Take Off); and

· Intrusive noise sources from background.

At the Three Sensitive Receivers / Alternative Monitoring Locations

· Number of flights;

· Flight path (Approach and Take Off); and

· Intrusive noise source from background.

The frequencies and parameters of noise measurement are summarized in Table 3.

Table 3 Frequency and Parameters of Noise Monitoring

Time Period	Data Logging Time, s	Parameters
Whole Monitoring Period (1 hour)	10^-1	LAeq (0.1s)

The noise levels due to different flight paths (fly in / out from the west and the east) for “Approach” and “Take Off” will bewere measured so as to obtain the maximum noise levels for each model for assessment. Measurements for approach and take-off flights (including approach, hovering, idling and take-off modes) were conducted continuously to capture the complete noise profile for noise calculation. A time history of flight was also recorded (e.g. video recording and photographing) for reference.

In addition, the following items were recorded during measurements for future noise calculation.

(i) The background noise levels at the measurement points during the absence of helicopter flight at the existing MFT Helipad;

(ii) Relative distance between noise source position and the measurement pointpoint and the locations;

(iii) The loading (number of persons) of each flight for future correction.

As agreed with EPD, replicated noise measurement (at least three sets data) for each helicopter operation mode was required to be recorded. The monitoring period may be changed subject to site situation and condition.

Noise measurements were conducted on 15 and 27 January, 23 March and 4 April 2005 afternoon respectively. On each measurement day, at least four sets of noise measurements data for each helicopter operation mode at each selected noise monitoring location were undertaken. The flight path on 15 January and 23 March 2005 was approaching from the east and take off to the west from the existing MFT Helipad; while the flight path on 27 January and 4 April 2005 was approaching from the west and take off to the east from the existing MFT Helipad.

Monitoring Procedures

The measurement wasere conducted as following the Fmield Monitoring procedure belows:

· All measurement will beas carried out simultaneously at the four selected locations. Time and duration of each helicopter operation will beas recorded at the reference monitoring point (China Merchants TowerShun Tak Centre Carpark). Therefore, the effect of each operation mode to each receiver caused by the proposed helipad will bewas evaluated using the logged data and the duration recorded based on acoustical principles.

· Parameters such as frequency weighting, the time weighting and the measurement time would beere set as follows:

- noise parameter : L_eq(0.1s)

- frequency weighting : A

- time weighting : Fast

- time measurement : Monitoring Period of 1 hour

· Prior to and after each noise measurement, the meter will beas calibrated using the Calibrator for 94 dB at 1000 Hz. If the difference in the calibration level before and after measurement is more than 1 dB (A), the measurement will beas considered invalid and repeat of noise measurement willould be required after re-calibration or repair of the equipment.

· The weather condition including wind speed and rainfall will beas collected from the Hong Kong Observatory.

· Noise monitoring iwas carried out continuously for at least 1 hour during the monitoring period. Monitoring data willas be rrecorded and stored automatically within the sound level meter system. In addition, site conditions and noise sources willwere be recorded during the monitoring process.

· All monitoring data within the sound level meter system will bewere downloaded through the computer software. Observation iwas recorded when intrusive noise iwas encountered.

· Noise monitoring will ould be cancelled in the presence of fog, rain, and wind with a steady speed exceeding 5 m/s, or wind with gusts exceeding 10 m/s. A potable wind speed meter would bewas used to check the wind speed during noise measurement.

Data Analysis

By using different sets of data registered from the sensitive receivers and the records obtained from the reference monitoring point, the noise level data L_max and L_Aeq(0.1s) at the sensitive receivers during different modes of operation of helicopters will beere obtained and measurement data for four days were summarised in Appendix 3.5..

Based on the data, the maximum noise levels of each mode of helicopter operation at each sensitive receiver will beere identified for assessment. Duration of each operation mode of helicopter and the respective measured noise levels L_Aeq(0.1s) would beere recorded during measurement. Based on the number of flights to be operated at the helipad, the noise level Leq_{(4 hours)} during 1900-2300 would be calculated by the following formula.:

Should iIntrusive noise from the background beif significant, these noise data will be excluded in the calculation.