Noise Monitoring Report - Shire of Cranbrook · Lloyd George Acoustics PO Box 717 Hillarys WA 6923...

Lloyd George Acoustics

PO Box 717 Hillarys WA 6923

T: 9401 7770 F: 9401 7770 E: [email protected] W: www.lgacoustics.com.au

Noise Monitoring Report

Cranbrook Motocross Reference: 12092214-01.docx

Member Firm of Association of Australian Acoustical Consultants

Report: 12092214-01.docx

Lloyd George Acoustics Pty Ltd ABN: 79 125 812 544

PO Box 717 Hillarys WA 6923

Offices: Ocean Reef Padbury Scarborough Waterford

Phone: Fax:

Email: Mobile:

9300 4188 9300 4199 [email protected]

0439 032 844

9401 7770 9401 7770 [email protected]

0400 414 197

9245 3223 9300 4199 [email protected]

0438 201 071

9313 3655 9300 4199 [email protected]

0427 388 876

Member of the Association of Australian Acoustical Consultants – (AAAC)

Prepared By: Lisa Douglas

Position: Project Director

Verified Daniel Lloyd

Date: 16 October 2012

This report has been prepared in accordance with the scope of services described in the contract

or agreement between Lloyd George Acoustics Pty Ltd and the Client. The report relies upon

data, surveys, measurements and results taken at or under the particular times and conditions

specified herein. Any findings, conclusions or recommendations only apply to the

aforementioned circumstances and no greater reliance should be assumed or drawn by the

Client. Furthermore, the report has been prepared solely for use by the Client, and Lloyd

George Acoustics Pty Ltd accepts no responsibility for its use by other parties.


CONTENTS

1 INTRODUCTION ___________________________________________________________ 1

2 APPROVAL CONDITIONS ____________________________________________________ 1

3 METHODOLOGY ___________________________________________________________ 1

3.1 NOISE MONITORNG LOCATIONS _________________________________________ 2

4 RESULTS _________________________________________________________________ 3

4.1 CLUB DAY ___________________________________________________________ 3 4.2 RACE DAY ___________________________________________________________ 3

5 STARTING AND FINISHING TIMES _____________________________________________ 6

6 DISCUSSION ______________________________________________________________ 6

APPENDICES

A Terminology


Reference: 12092214-01.docx Page 1

1 INTRODUCTION

This report has been prepared to provide details of the noise monitoring undertaken at the ‘Cranbrook Motocross Track’, located in Cranbrook, Western Australia.

The Shire of Cranbrook requested that noise monitoring be undertaken for two events to be held at the Motocross Track and these were:

Club Day held Saturday 8th September 2012

Race Day held Saturday 22nd September 2012

Lloyd George Acoustics undertook the noise monitoring for both Events.

Appendix A contains a description of some of the terminology used throughout this report.

2 APPROVAL CONDITIONS

It is understood that the ‘Cranbrook Motocross Association WA’ have developed their own Noise Management Plan and that the Shire of Cranbrook will use the results of the noise monitoring in the development with the Noise Management Plan.

The proposed new Noise Regulation Amendments recognise the community benefits of motor racing facilities and provides for the approval of such facilities by the Shire CEO. The approval would be considered following an approved Noise Management Plan and consideration of the noise sensitive premises affected by the noise.

3 METHODOLOGY

Under the Regulations, there are certain requirements that must be satisfied when undertaking measurements and are defined in Regulations 19, 20, 22 and 23 and Schedule 4. In undertaking the measurements, these have been satisfied, specifically noting the following:

The noise data loggers used were:

o ARL Type 315 (S/N: 15-203-533);

o ARL Type 315 (S/N: 15-301-468);

o ARL Type 316 (S/N: 16-004-041);

o ARL Type 316 (S/N: 16-707-041);

All equipment holds current laboratory certificates of calibration that are available upon request. The equipment was also field calibrated before and after the Event and found to be within +/- 0.5 dB.

Each microphone was fitted with a standard wind screen.

The microphone was at least 1.2 metres above ground level and at least 3.0 metres from reflecting facades (other than the ground plane).



3.1 NOISE MONITORNG LOCATIONS

The Shire of Cranbrook selected the noise measurement locations. The noise levels were continually monitoring throughout the events on both days at the three fixed measurement locations, consisting of two residential locations and one within the motocross venue.

The fixed measurement locations include:

Logger 1 - at the Motocross venue, Rockwell Road Cranbrook

Logger 2 - at the boundary fence of the nearest noise sensitive receiver, opposite Motocross track

Logger 3 - cricket pitch at Fredrick Square, Town Centre.

The measurement locations are shown in Figure 3.1.

Figure 3.1 – Fixed Noise Measurement Locations



4 RESULTS

4.1 CLUB DAY

The noise monitoring results at the three fixed locations are presented graphically in Figure 4.1. Meteorological conditions during the day were light north to northeasterly winds. Wind from this direction would enhance the noise from the motocross track within the town.

The results show an increase in levels during racing with average levels at the nearest noise sensitive receiver during some races around 66 dB(A). A correlation coefficient was calculated to be 0.74. This indicates a reasonable relationship between the noise levels at the Motocross site and those measured simultaneously at the nearest noise sensitive receiver.

The correlation coefficient was also calculated between the noise levels measured at the motocross track and the noise levels measured at the cricket pitch, Fredrick Square. In this case, the correlation coefficient was 0.25. This indicates a moderate relationship between these measurements. The results indicate average levels during racing around 50-52 dB(A).

4.2 RACE DAY

The noise monitoring results at the three fixed measurement locations are presented graphically in Figure 4.2. . Meteorological conditions during the day were very strong southwesterly winds in the morning and a strong westerly winds in the afternoon. These winds would significantly influence the results, in particular as the noise from the motocross would have been reduced as well as being masked by noise from the wind in the trees etc.

The graph shows that there was a very poor relationship between noise levels measured at the motocross track and those measured simultaneously at the nearest noise sensitive receiver and the cricket pitch at Fredrick Square. The correlation between the motocross site and each of these locations was calculated to be 0.02 and -0.04 respectively. This indicates that there is no relationship between the measured noise levels. Noise levels were also monitored on a roving basis during the morning of the Event when weather permitted. The locations were selected to represent the residential areas surrounding the venue.

The results of the roving monitoring measurements are presented in Table 4.1.

Table 4.1 - Results of Roving Noise Measurements

Location Time (am) Sound level LAeq, dB(A)

Sound level LA10, dB(A) Comments

Three metres away from motocross trackside 10.10 70 75 During racing of 85cc motorbikes

At boundary of the nearest resident Rockwell Road

10.30 55 57

During racing worst case bikes, open class 450cc and larger.

Audible Intermittently at boundary, not dominant

At boundary of residence at 110 Grenfell Street 11.00 50 53.2

During racing worst case bikes, open class 450cc and larger. Barely audible intermittently.

At boundary of residence corner of King and Armstrong Street

11.20 46 48 Barely audible

40

50

60

70

80

90

100

9:30

9:40

9:50

10:00

10:10

10:20

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15:10

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15:30

So

un

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MX Trackside Nearest Noise Sensitive Receiver Cricket Pitch, Fredrick Square

Figure 4.1 Club Day Combined Noise Monitoring Results

40

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100

9:30

9:40

9:50

10:00

10:10

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So

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MX Trackside Nearest Noise Sensitive Receiver Cricket Pitch, Fredrick Square

Figure 4.2 Race Day Combined Noise Monitoring Results



5 STARTING AND FINISHING TIMES

The following starting and finishing times were noted for each Event days.

Club day started at 9.30am and finished at 3.30pm

Race day started at 9.30am and finished at 3.00pm

6 DISCUSSION

The results show that sound levels from the motocross track varied considerably between the two race days. This was due to the weather conditions.

For the club day, the wind was from the north (worst-case) and the noise from the event was clearly audible at the nearest noise sensitive premises as well as in the town. When compared to the noise impacts assessment prepared for the venue (Lloyd George Acoustics Ref 11021762-01 March 2011), there is an excellent correlation between measured and predicted levels.

For the race day, the wind direction/strength was a strong southwesterly in the morning and a strong westerly winds in the afternoon. This would result in reduced noise levels to the south as well as the noise being masked by the wind in the tress etc. As such, the correlation between the measured noise levels at trackside and those measured at the nearest residence and town was not good on this day. Our observations on this day were that the worst-case bikes (open class 450cc and larger) were audible intermittently at the nearest residence, but were not a dominant noise source. Sound level measurements conducted closer to the town site were barely audible almost inaudible.

Other observations were that the Motocross sound levels are generally louder at the commencement of a race, due to all the motorbikes being in close proximity to one another. The motorbikes then disperse throughout the motocross track and the levels are reduced.

The Noise Management Plan prepared by the WA Motocross Association would outline times of operation, and an agreed level of use along with other noise control measures to be implemented. Currently, taking into consideration the number of events proposed, the sound levels from the motocross track would not be considered a major impact, however, should there be a significant increase in the use of the venue in the future, the Noise Management Plan would need to be reviewed.

As discussed previously, the proposed new Noise Regulation Amendments recognise that although motor racing is noisy and may impact on the surrounding area, there are community benefits of motor racing facilities and provides for the approval of such facilities by the Shire CEO.


Reference: 12092214-01.docx

Appendix A Terminology

Reference: 12092214-01.docx Page A1

The following is an explanation of the terminology used throughout this report.

Decibel (dB) The decibel is the unit that describes the sound pressure and sound power levels of a noise source. It is a logarithmic scale referenced to the threshold of hearing.

A-Weighting An A-weighted noise level has been filtered in such a way as to represent the way in which the human ear perceives sound. This weighting reflects the fact that the human ear is not as sensitive to lower frequencies as it is to higher frequencies. An A-weighted sound level is described as LA dB.

Sound Pressure Level (Lp) The sound pressure level of a noise source is dependent upon its surroundings, being influenced by distance, ground absorption, topography, meteorological conditions etc and is what the human ear actually hears. Using the electric heater analogy above, the heat will vary depending upon where the heater is located, just as the sound pressure level will vary depending on the surroundings. Noise modelling predicts the sound pressure level from the sound power levels taking into account ground absorption, barrier effects, distance etc.

LASlow This is the noise level in decibels, obtained using the A frequency weighting and the S time weighting as specified in AS1259.1-1990. Unless assessing modulation, all measurements use the slow time weighting characteristic.

LAFast This is the noise level in decibels, obtained using the A frequency weighting and the F time weighting as specified in AS1259.1-1990. This is used when assessing the presence of modulation only.

LAmax An LAmax level is the maximum A-weighted noise level during a particular measurement.

LA1 An LA1 level is the A-weighted noise level which is exceeded for one percent of the measurement period and is considered to represent the average of the maximum noise levels measured.

LA10 An LA10 level is the A-weighted noise level which is exceeded for 10 percent of the measurement period and is considered to represent the “intrusive” noise level.

LAeq The equivalent steady state A-weighted sound level (“equal energy”) in decibels which, in a specified time period, contains the same acoustic energy as the time-varying level during the same period. It is considered to represent the “average” noise level.

LA90 An LA90 level is the A-weighted noise level which is exceeded for 90 percent of the measurement period and is considered to represent the “background” noise level.


Reference: 12092214-01.docx Page A2

Background Noise Background noise or residual noise is the noise level from sources other than the source of concern. When measuring environmental noise, residual sound is often a problem. One reason is that regulations often require that the noise from different types of sources be dealt with separately. This separation, e.g. of traffic noise from industrial noise, is often difficult to accomplish in practice. Another reason is that the measurements are normally carried out outdoors. Wind-induced noise, directly on the microphone and indirectly on trees, buildings, etc., may also affect the result. The character of these noise sources can make it difficult or even impossible to carry out any corrections.

Chart of Noise Level Descriptors

Typical Noise Levels

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