East Derwent Highway UpgradeDevelopment Application

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Appendix H.

Acoustic Assessment

Received 21.08.2020

Jacobs Group (Australia) Pty Limited ABN 37 001 024 095

IS262318.MM.20200324

East Derwent Highway Upgrade

Road Traffic Noise Assessment

27 July 2020

Department of State Growth

IS262318 | REV B

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Road Traffic Noise Assessment

2

1. Introduction

Jacobs Group (Australia) Pty Ltd was engaged by Department of State Growth to undertake a noise

impact assessment of the proposed upgrade to East Derwent Highway (A0029) between Golf Links

Road (Link 6 – 3.00km) and Sugarloaf Road (Link 6 – 4.40km) at Geilston Bay.

The planned upgrade works include duplication of the existing single carriageway to provide four

through lanes (two each way) and installation of traffic signals at the Geilston Bay Road/Clinton Road

intersection. Figure 1 shows the project location. The proposed improvements are a component of the

overall commitment by the Tasmanian Government to improve the East Derwent Highway between

Lindisfarne and Grasstree Hill Roundabout.

Figure 1 - Project overview (source: https://www.transport.tas.gov.au/road/projects/eastderwenthighwayupgrade)

Terms and definitions used in this report are summarised in Appendix A: Acoustic Glossary.

2. Applicable noise requirements

The applicable noise requirements for each planning zone impacted by the upgrade to East Derwent

Highway are provided by the Clarence City Council’s Interim Planning Scheme 2015 (the Scheme). The

Scheme Zones impacted are a) Utility Zone, b) Community Purpose Zone and c) Open Space Zone.

Each of these Zones has an ‘Applicable Standard’ specifically for noise. Pursuant to Clause 7.5.3,

compliance with an Applicable Standard is achieved by either meeting the Standard’s Acceptable

Solution or Performance Criteria. To ensure that noise emissions do not cause environmental harm

and do not have unreasonable impact on residential amenity on land within a residential zone, it is

required to comply with either the applicable Acceptable Solution or Performance Criteria within the

Scheme. Each of the impacted Zone’s Acceptable Solution for noise is:

Acceptable Solution A1 Noise emissions measured at the boundary of a residential zone must

not exceed the following:

(a) 55 dB(A) (LAeq) between the hours of 7.00 am to 7.00 pm;

(b) 5dB(A) above the background (LA90) level or 40dB(A) (LAeq), whichever is the lower,

between the hours of 7.00 pm to 7.00 am;

(c) 65dB(A) (LAmax) at any time.

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Measurement of noise levels must be in accordance with the methods in the Tasmanian Noise

Measurement Procedures Manual, issued by the Director of Environmental Management,

including adjustment of noise levels for tonality and impulsiveness. Noise levels are to be

averaged over a 15 minute time interval.

However, through undertaking a noise assessment for the project, through means of noise

measurement and computer-based model predictions, it was determined that the project currently,

and in its 10-year future build scenario, will exceed the requirements of Acceptable Solution A1.

Therefore, the Performance Criteria P1 is relied upon to ensure that noise emissions do not cause

environmental harm and do not have unreasonable impact on residential amenity on land within a

residential zone.

Each of the impacted Zone’s Performance Criteria for Noise is:

Performance Criteria P1 Noise emissions measured at the boundary of a residential zone must

not cause environmental harm within the residential zone.

Environmental harm is a defined term within the Scheme which refers to the definition in the

Tasmanian Environmental Protection Authority’s (EPA) Environmental Management and Pollution

Control Act 1994 (the Act). Environmental harm is not quantitively defined with respect to noise

emissions in the Act, rather a series of definitions and provisions are provided. In the context of noise,

environmental harm is to be treated as material environmental harm, particularly if it “involves an

actual adverse effect on the health or safety of human beings that is not negligible.”

For the purpose of the Development Application, and as agreed with Clarence City Council, the adverse

impact measure of environmental harm has been assessed using State Growth’s Tasmanian State

Road Traffic Noise Management Guidelines (2015). This is the most fit-for-purpose document to

assess the impacts of road traffic noise in the Tasmanian road network and is also endorsed by EPA

Tasmania. Based on the Guidelines, the adverse impact criteria include both an exceedance of 63

dB(A) LA10, 18hour and a change in noise level of ≥3 dB(A) (which represents the minimum change in

noise level humanly perceptible). This measure has been chosen to measure the extent of

"environmental harm" from traffic noise, associated with the proposed development.

Table 1: Noise Impact Criteria

Compares existing traffic noise with 10-year future traffic

noise

10-Year Future Build Scenario

No. of receivers with ≥3 dB(A) increase above existing levels

Existing

No. of receivers with L10,18hour

≤ 63 dB(A) Not impacted

No. of receivers with L10,18hour

> 63 dB(A) Adversely impacted

3. Methodology

The methodology used to undertake the noise impact assessment against the Scheme was discussed

and agreed with Clarence City Council.

The following approach has been adopted in accordance with State Growth’s Tasmanian State Road

Traffic Noise Management Guidelines (October, 2015) to assess airborne noise from road traffic:

Measurement of road traffic noise at sensitive receivers in the vicinity of the road alignment. This

has been undertaken by Jacobs.

Creation of an acoustic model of the existing operational highway and proposed upgrade in the

vicinity of the project area.

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Prediction of noise levels for the following scenarios:

Existing, unchanged highway (no build);

nominal 10 years after project opening, including expected growth in road traffic (10-Year

future build).

Comparison of the predicted noise levels with the relevant noise criteria.

4. Assessment

4.1 Identification of receivers

There are approximately 919 buildings within a 300 metre radius of the project, and of the 919

buildings, 724 residential buildings have been identified to be relevant to the operational road traffic

noise assessment. A summary of residential building receivers is provided in Figure 2.

There are also two existing approved subdivisions at the north-west end of the project site, one of

which is currently under construction, which will comprise approximately 130 residential lots adjacent

to the highway. Noise assessments were required to be undertaken for both subdivision developments,

based on a duplicated highway and applying appropriate mitigations (if required).

As the Guidelines would only provide mitigation to residential receivers, depending on assessment of

any adverse impacts, this assessment focuses on the Project impacts on surrounding residential

receivers and therefore, does not include assessment of the school or any other small commercial

businesses in the project area.

Figure 2 - Overview image of residential buildings within a 300 metre radius of the project

Project Location - Site Map

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4.2 Noise measurements

Noise monitoring has been conducted by Jacobs at four locations along the East Derwent Highway

road alignment between 17th October to 25th October 2019, as shown in Figure 2. All acoustic

monitoring has been conducted in accordance with EPA Tasmania’s Noise Measurement Procedures

Manual (July 2008). The noise monitoring locations were undertaken at the following residential

addresses:

Location 1: 296 East Derwent Hwy, Geilston Bay

Location 2: 6 Dumbarton Drive, Geilston Bay

Location 3: 4/41 Clinton Road, Geilston Bay

Location 4: 13/73 Clinton Road, Geilston Bay

Traffic counts were conducted simultaneously at three locations, along the East Derwent Hwy.

4.3 Predicted noise levels

The acoustic software SoundPLAN version 8.1 has been used to implement the Calculation of Road

Traffic Noise (CoRTN) methodology1 to predict the noise impact assessment at residential buildings

along the project alignment.

The prediction was based on current (Year 2021) traffic volumes for the unchanged, existing road

alignment and based on Year 2031 traffic volumes for the future design road alignment. The CoRTN

algorithms have been used widely in Tasmania and nationally for road traffic noise assessments and

were developed to calculate LA10,18hr noise levels for road traffic noise, in accordance with the

Guidelines.

Other modelling inputs included in the acoustic model include terrain, road surface details, noise

source heights (tyres, engines and exhausts), receiver heights, traffic volumes and speeds.

The predicted existing LA10, 18hr traffic noise levels at measurement locations 1 to 4 were compared

with the measured LA10, 18hr traffic noise levels and used to validate the acoustic model to within ± 2

dB(A) of the measured noise levels. The validation was found to be consistent with Section 6.4, point 7

of the Guidelines.

5. Results

Key findings of the road traffic noise impact assessment are summarised in Table 2 below, including an

assessment of predicted noise levels against the target limits in the Guidelines and the perceptible

change in noise level criterion.

The figures in Appendix B provide further detail on the findings of the assessment through a graphical

representation of the predicted noise levels for all residential receivers considered, including a change

in noise level analysis.

1 Calculation of Road Traffic Noise, Department of Transport, Welsh Office, HMSO, 1988.

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Table 2: Summary of project noise impact assessment

Compares existing traffic noise with 10-year future traffic

noise

10-Year Future Build Scenario

No. of receivers with ≥3 dB(A) increase above existing levels

Existing

No. of receivers with L10,18hour

≤ 63 dB(A) 0

No. of receivers with L10,18hour

> 63 dB(A) 0

Results from the acoustic model predicted that a total of 0 receivers are predicted to be adversely

impacted by traffic noise levels in the 10-Year (2031) Future Build scenario for the East Derwent

Highway Upgrade, Geilston Bay. That is, no receivers are predicted to experience a change equal to or

greater than 3 dB(A) and a noise level of above 63 dB(A).

6. Discussion – Performance Criteria and Mitigation Eligibility

This assessment has addressed environmental harm considerations under noise specific Performance

Criteria P1 for the zones impacted by the East Derwent Highway Upgrade project through a change in

noise level analysis. The analysis determined if changes in noise levels as a result of the project would

have a noticeable, adverse effect on residential receivers. Residential receivers were said to be at risk of

environmental harm if noise levels in the 10-Year Future build scenario;

Exceeded the target noise level of 63 dB(A) specified in the Guidelines, and

Resulted in a noticeable increase in noise level, numerically defined in the Guidelines as +3 dB(A).

Whilst a number of receivers already exceed the target noise level of 63 dB(A) in the existing “no

build” scenario, no residential receivers were identified as experiencing a noticeable increase in noise

level in the 10-Year Future build scenario. As such, since both of the above criteria are satisfied for all

receivers, the assessment has found no receivers will be at risk of environmental harm due to the

highway upgrade and therefore Performance Criteria P1 relating to noise requirements for each of the

impacted planning zones within the Scheme have been satisfied.

It is acknowledged that the building eligibility matrix for determining mitigation requirements in State

Growth’s Guidelines focuses solely on numerical target values, and not on the change in noise levels as

a result of a project. However, page 10 of the Guidelines (Part A: Non-Technical Summary) also

stipulates;

“…the Department may not always be able to achieve the 63 dB(A) target limit anyway. In each case it

will apply tests of reasonableness, practicality and cost-effectiveness. Because noise increase of 3

dB(A) or less will not be readily perceptible, a numerical exceedance of 63 dB(A) by less than 3 dB(A)

will not necessarily result in a perceptible loss of amenity.”

Tests of “reasonableness, practicality and cost-effectiveness” described above must consider

perceptible consequences to houses relative to the cost of mitigation, recognising that exceedances of

a target noise level by less than 3 dB(A) will not actually be perceptible to most people, even though

they are numerically measurable (page 5, Part C: Full Guidelines).

As such, the eligibility matrix was used in conjunction with a change in noise level analysis to

determine if increases in noise resulting from the upgrade would be noticeable and contribute to

environmental harm, thereby requiring mitigation. As previously indicated, since no receivers will

experience a perceptible increase in noise level due to the upgrade, the results of this assessment

indicate it is appropriate to proceed without mitigation, based on the Guideline’s required tests of

reasonableness, practicality and cost-effectiveness.

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Appendix A: Acoustic Glossary

Term Definition

Decibel

Sound pressure levels are expressed in units of decibels - a logarithmic ratio between the

measured sound pressure level and the reference pressure (2x10-6 Pascal). Typical noise levels

are presented below:

Sound Pressure Level dB(A) Example

130 Threshold of pain

120 Jet aircraft take-off at 100 m

110 Power tool at 1 m

100 Nightclub

90 Heavy trucks at 5 m

80 Kerbside of busy street, excavator at 15 m

70 Loud radio (in typical domestic room)

60 Office

50 Domestic fan heater at 1 m

40 Living room

30 Theatre

20 Rural environment on still night

10 Sound insulated test chamber

0 Threshold of hearing

dB(A)

The A-weighted sound pressure level in decibels, denoted dB(A) is the unit generally used for

the measurement of environmental, transportation or industrial noise. The A-weighting scale

approximates the sensitivity of the human ear and correlates well with subjective perception of

sounds.

An increase or decrease in sound level of approximately 10 dB corresponds respectively to a

subjective doubling or halving in loudness. A change in sound level of 3dB is considered just

noticeable.

LA10 The A-weighted sound pressure level that is exceeded for 10 per cent of the measurement

period. Usually used to represent the background noise level.

LA10 (18 hour)

The A-weighted noise level exceeded 10% of the time over the 18-hour period between 6 am

and midnight. When applied to traffic, it relates to the noise from the traffic only.

Noise-Sensitive

Receiver

Residential dwellings, aged persons homes, hospitals, motels, caravan parks, and other

buildings of a residential nature.

Schools, kindergartens, libraries and other noise sensitive community buildings.

Research laboratories, buildings with sensitive equipment, heritage listed structures and items.

Boundary of

Residential Zone

Boundary of (residential) noise-sensitive receiver.

Sound Pressure

Level

The sound pressure level (SPL) is the logarithmic ratio of the sound pressure (P) to a reference

pressure (Pref : 2x 10-5 for applications in air) SPL= 20 log(P/Pref) dB.

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Appendix B: Predicted Noise Levels

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B

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X

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x

B

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