Road Traffic Noise
Guidelines
Transport Services Division
ENVIRONMENT
Standards & Guidelines
Department of Planning Transport and Infrastructure
Road Traffic Noise Guidelines
First published:
1990
First Update:
February 2002
Second Update:
March 2007
Third Update:
December 2014
Version:
4
Copyright Department of Planning Transport and Infrastructure
77 Grenfell Street Adelaide, SA 5000
The guidelines were developed by the Environmental Group, Projects Directorate, Safety and
Services Division with the assistance of Resonate Acoustics and Roads and Maritime Services.
It has been approved and authorised for use by Departmental staff and its authorised agents by:
General Manager, Asset Management
23 December 2014
and endorsed by the Environment Protection Authority on 28 January 2015.
Extracts may be reproduced providing the subject is kept in context and the source is
acknowledged. Every effort has been made to supply complete and accurate information. This
document is subject to continual revision and may change.
To ensure you have the most up-to-date version of this document refer to:
http://www.dpti.sa.gov.au/standards/environment
For information regarding the interpretation of this document contact:
Environmental Systems Unit, Asset Management
Telephone: (08) 8343 2686 Facsimile: (08) 8343 2905
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DPTI Road Traffic Noise Guidelines
TABLE OF CONTENTS
GLOSSARY .................................................................................................................... 5
1 INTRODUCTION ....................................................................................................... 6
2 THE NATURE OF ROAD TRAFFIC NOISE .............................................................. 8
2.1
WHAT IS NOISE? ............................................................................................................................... 8
2.2
PRESSURE OR LOUDNESS ............................................................................................................. 8
2.3
HUMAN PERCEPTION TO A NOISE LEVEL CHANGE .................................................................... 9
2.4
THE A-WEIGHTED DECIBEL SCALE ............................................................................................... 9
2.5
TYPES OF ROAD NOISE ................................................................................................................. 11
2.6
FACTORS INFLUENCING ROAD TRAFFIC NOISE GENERATION .............................................. 11
2.7
NOISE DESCRIPTORS..................................................................................................................... 13
2.8 NOISE MITIGATION MEASURES .................................................................................................... 13
2.8.1 Noise control at the source ......................................................................................................... 14
2.8.2 Noise control along the transmission path .................................................................................. 14
2.8.3 Noise control at the receiver ....................................................................................................... 14
3 ASSESSMENT PROCESS ...................................................................................... 16
3.1 SCOPE OR APPLICATION OF THE GUIDELINES ......................................................................... 16
3.1.1 Scope Definition .......................................................................................................................... 16
3.1.2 Noise Sensitive Receivers .......................................................................................................... 16
3.1.3 Noise Catchment Areas and Grouping Receivers ...................................................................... 17
3.1.4 Responsibility for Mitigating Traffic Noise ................................................................................... 17
3.2 NOISE ASSESSMENT CRITERIA.................................................................................................... 18
3.2.1 Noise Descriptors ........................................................................................................................ 18
3.2.2 Noise Criteria .............................................................................................................................. 18
3.2.3 Relative Increase Criterion .......................................................................................................... 19
3.2.4 Transitioning Between Noise Catchment Areas with Different Criteria ...................................... 19
3.2.5 Noise Assessment Location........................................................................................................ 19
3.2.6 When should Noise Mitigation be considered?........................................................................... 20
3.2.7 Flowchart of Assessment Process .............................................................................................. 20
4 NOISE MITIGATION DESIGN ................................................................................. 23
4.1
ROAD DESIGN ................................................................................................................................. 23
4.2 NOISE BARRIERS ............................................................................................................................ 23
4.2.1 Barrier Design ............................................................................................................................. 24
4.2.2 Noise Barrier Benefit ................................................................................................................... 24
4.2.3 Barrier Materials .......................................................................................................................... 25
4.3
PROPERTY TREATMENT ................................................................................................................ 25
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DPTI Road Traffic Noise Guidelines
4.3.1
4.3.2
4.3.3
4.3.4
4.3.5
4.4
Facade Treatment Criteria .......................................................................................................... 26
Facade Treatment Packages ...................................................................................................... 27
Facade Treatments to Noise Sensitive Non-Habitable Spaces .................................................. 30
Mechanical Ventilation ................................................................................................................ 30
Acoustic Screening ..................................................................................................................... 30
NOISE MITIGATION GENERAL NOTES ......................................................................................... 30
5 PROCESS FOR ASSESSING ROAD TRAFFIC NOISE ......................................... 31
5.1
GENERAL ......................................................................................................................................... 31
5.2
FORMAL NOTIFICATION OF A ROAD PROJECT ......................................................................... 32
5.3
NOISE ASSESSMENT BOUNDARY ................................................................................................ 32
5.4 MODELLING ROAD TRAFFIC NOISE ............................................................................................. 33
5.4.1 Noise Model Validation ............................................................................................................... 33
5.4.2 Noise Model inputs ..................................................................................................................... 33
5.4.3 Road surface corrections ............................................................................................................ 34
5.4.4 Meteorological Effects................................................................................................................. 34
5.5 DEVELOPMENT OF A NOISE MITIGATION PLAN ........................................................................ 34
5.5.1 Reasonable and Practicable Mitigation ...................................................................................... 34
5.5.2 Community Acceptance .............................................................................................................. 35
5.5.3 Noise Mitigation Plan .................................................................................................................. 36
5.6
DATABASE OF NOISE MITIGATION TREATMENTS .................................................................... 36
5.7
POST CONSTRUCTION VERIFICATION ........................................................................................ 36
6. BIBLIOGRAPHY .................................................................................................... 37
APPENDIX A................................................................................................................. 38
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DPTI Road Traffic Noise Guidelines
GLOSSARY
dB
Decibel. A unit of measurement used to express sound level. It is based
on a logarithmic scale, which means a sound that is 3 dB higher has
twice as much energy.
dB(A)
Units of the A-weighted sound level. A-weighting is defined in the
International standard IEC 61672:2003 and relates to the measurement
of sound pressure level. A-weighting is applied to instrument-measured
sound levels in effort to account for the relative loudness perceived by
the human ear at typical sound pressure levels, as the ear is less
sensitive to low audio frequencies.
EPA
South Australian Environment Protection Authority.
Equivalent
The Leq is the value of a steady noise that would have the same
Noise Level - acoustic energy as the varying noise, over the same time period. All
Leq
references in these Guidelines are to A-weighted noise levels i.e. LAeq
LAeq (15hr)
(LAeq day)
The noise descriptor refers to the A-weighted energy averaged
equivalent noise level over a 15 hour day time period between 7 a m
and 10 p m.
LAeq (9hr)
(LAeq night)
The noise descriptor refers to the A-weighted energy averaged
equivalent noise level over a 9 hour night time period between 10 p m
and 7 a m.
L10
The noise descriptor L10 refers to the noise level which is exceeded for
10% of the time in a given measurement period, and corresponds to the
average of the upper noise levels.
RW
Weighted Sound Reduction Index—A laboratory measured value of the
acoustic separation provided by a single building element (such as a
partition). The higher the RW the better the noise isolation provided by a
building element.
Rw + Ctr
A measure of the sound insulation performance of a building element
with a Ctr spectrum adaptation term placing greater emphasis on the
low frequency performance.
Insertion
Loss (IL)
Insertion loss of barriers is the difference in sound pressure levels at a
specified receiver position before and after the installation of barrier,
provided that the noise source, terrain profiles, interfering obstructions
and reflecting surfaces, if any, have not changed.
Significant
When used in context with a change in noise level, the term ‘significant’
relates to an increase in level of greater than 2 dB(A) (i.e. ≥ 2.1 dB(A))
Residual
Exceedance
The remaining exceedance of a noise assessment criterion following
the application of noise mitigation measures.
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DPTI Road Traffic Noise Guidelines
1 INTRODUCTION
Increasing volumes of traffic and rising community awareness of the environment has led
to traffic noise becoming an increasingly important consideration in urban development.
The conflicting requirements of providing a quiet environment for people to live in, whilst
maintaining a high standard road network for the safe and efficient transportation of
increasing numbers of goods and people, presents a challenge to planners and designers
involved in land-use planning and road location and design.
As road traffic noise is related to the volume of traffic, high levels are generally associated
with the arterial road system. In 2010/11 the South Australian transport task totalled 28.8
billion passenger-kilometres and 37.5 billion tonne-kilometres. Since 2000/01 the South
Australian domestic passenger and freight tasks have grown by 5.1% and 17.4%
respectively.
Exposure to high traffic noise levels can give rise to various problems, including
annoyance from disruption to leisure activities such as listening to music or watching
television; speech interference; sleep disruption; decreased work efficiency and
proficiency; and fatigue. The control of road traffic noise is therefore seen as having
social and economic benefits to the community.
There is, however, a wide range of sensitivity to noise within the community. Some
people are likely to be disturbed at relatively low levels of traffic noise, while others may
not be disturbed even at relatively high levels. Similarly a range of individual responses
could be expected for any given change in noise level. Tolerance to noise is influenced
by the degree of acclimatisation, the level and nature of the intruding noise and the level
of the background or ambient noise. The annoyance a person feels can also be
influenced by the extent to which traffic noise interferes with activities such as reading,
sleeping or watching television.
The Department, along with a range of other Federal, State and local agencies has a role
in addressing the issue. The Department has a General Environmental Duty under
Section 25 of the Environment Protection Act 1993. The Road Traffic Noise Guidelines is
the Departments response to satisfying the General Environmental Duty in relation to
infrastructure works. The Department will take reasonable and practicable measures to
reduce the impact of traffic noise.
Complementary measures being undertaken by the Department to reduce the impacts of
road traffic noise include enforcement of in-service vehicle noise emissions, contributing
to setting national standards for new vehicles, and measures to manage travel demand
and promote alternative modes.
The Development Division of DPTI provides guidance to planning authorities, developers
and builders on measures that can be adopted to mitigate the impacts of traffic noise. In
2013 the Minister’s Specification SA 78B and the Noise and Air Emissions Overlay policy
was introduced to protect sensitive land uses (e.g. residential) from noise emissions
generated by major transit corridors. Where the Overlay is applied by Councils through
the Development Plan Amendment process this provides protection to new dwellings from
traffic noise. Further information is available in Reducing Noise and Air Impacts from road,
rail and mixed land use – A Guide for builders, designers and the community.
The Road Traffic Noise Guidelines provides guidance to Departmental staff, consultants
and contractors in addressing road traffic noise as a key part of infrastructure project
development.
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DPTI Road Traffic Noise Guidelines
These Guidelines set out the process to be followed and criteria to be applied when
assessing the road traffic noise impacts of infrastructure projects involving new roads
and/or major upgrading of existing roads. This assessment is to be undertaken during the
planning and design phase of such projects and documented in a Noise Mitigation Plan
and the Environmental Impact Assessment Report or Project Impact Report, then
implemented during construction.
These Guidelines should also be used in conjunction with the Department’s Noise
Mitigation Manual that provides details on acoustic issues and design principles in relation
to the use of noise barriers and architectural acoustic treatments for noise sensitive
properties.
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DPTI Road Traffic Noise Guidelines
2 THE NATURE OF ROAD TRAFFIC NOISE
2.1
WHAT IS NOISE?
Noise can be defined as unwanted sound. Sound is the sensation produced in the ear as
a result of fluctuations in air pressure, superimposed on the steady atmospheric pressure.
The ear responds to these much smaller fluctuations with great sensitivity.
The frequency of a sound is the rate at which the fluctuations occur. Practically all sounds
contain a mixture of frequencies. Screeching or whistling noises are composed mainly of
high frequency sound while rumbles or booms are composed mainly of low frequency
sound. As an illustration, middle C on a piano is 256 Hz (hertz, or cycles per second),
while 1,000 Hz is about the frequency of the high C that sopranos strive for.
The auditory senses are normally limited to frequencies between 20 and 20,000 Hz in a
young person. The ability to hear the higher frequencies decreases with age, such that it
is not uncommon for a 50 year old person to be unable to hear sounds above 8,000 Hz.
2.2
PRESSURE OR LOUDNESS
The range of sound pressures (loudness) encountered in everyday life extends from those
which the human ear can just detect (the ‘threshold of hearing’) to those many times as
great (approaching, and sometimes exceeding, the ‘threshold of pain’). The international
standard unit of acoustic pressure is the micropascal (µPa), but as the range between the
faintest audible sound and the loudest the ear can stand is so enormous (20 µPa to 63
million µPa), it would be very awkward to express sound pressure fluctuations in these
units. Instead, this range is ‘compressed’ by expressing the sound pressure on a
logarithmic scale, which is also the way the human hearing mechanism responds to
pressure variations.
Sound is therefore described in terms of the Sound Pressure Level (SPL), the unit of
which is the decibel (dB). In decibel notation, the entire audible range of sound pressure,
described above with such large numbers in micropascals, runs from 0 to 130 dB. Zero
decibels is an arbitrary noise energy intensity approximately equal to the lower limit of
hearing of a young adult.
It must be remembered that the decibel scale is logarithmic. On a linear scale, the total
sound pressure from two identical noise sources would be twice that from one of the
sources alone. However, on the logarithmic decibel scale, the total sound pressure level
from two identical noise sources is 3 dB higher than the level from either source alone. In
other words, in the case of road traffic noise, a doubling of traffic flow leads to a 3 dB
increase in the sound pressure level. Similarly, a halving of traffic flow results in a 3 dB
decrease.
Although the ear can distinguish change of about 1 dB in a pure tone, the minimum that
can be detected for a varying source such as traffic noise is about 3 dB. In addition, each
increase of approximately 10 dB sounds subjectively twice as loud to the ear (Refer
Section 2.3). Therefore a noise measured at 80 dB will sound twice as loud as one which
registers 70 dB, which in turn will appear twice as loud as one which registers 60 dB.
Although a risk of temporary or permanent damage exists for people exposed for
prolonged periods to noise levels above about 90 dB, higher levels can be tolerated
without damage for shorter exposure times.
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DPTI Road Traffic Noise Guidelines
2.3
HUMAN PERCEPTION TO A NOISE LEVEL CHANGE
How we subjectively perceive a change to traffic noise exposure under typical living
conditions versus a noise level change is outlined in the table below:
2.4
Perceived volume change
Noise level change (dB)
Doubling or halving
6 – 10
Noticeable change
3–5
Not noticeable change
0–2
THE A-WEIGHTED DECIBEL SCALE
Although the perceived loudness of a sound depends primarily on sound pressure, it is
also influenced by frequency. The human ear is most sensitive to mid-range and high
frequencies (approximately 1,000 – 8,000 Hz) and is less sensitive to the lower
frequencies.
To ensure measured levels approximate the human response, a weighting scale is used.
It is known as the ‘A’ scale and the units are referred to as ‘A’ weighted decibels (written
as dB(A)). The dB(A) scale discriminates between sounds in much the same way as
people do.
It should be noted that noise levels (whether predicted or measured) are usually
expressed as whole numbers. Decimals below 0.5 should be rounded down, and those
equal to or greater than 0.5 should be rounded up to the nearest dB.
Figure 2.1 The “A-Weighted” Curve
NOISE LEVEL DIFFERENCE dB
+10
0
-10
-20
-30
-40
31
63
125
250
500
1000
2000
4000
8000
16000
FEQUENCY Hz
The noise levels emitted by vehicles typically varies with frequency, and a typical
relationship between noise level and frequency is shown in Figure 2.2.
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DPTI Road Traffic Noise Guidelines
Figure 2.2 Typical Noise Level - Frequency Relationship
NOISE LEVEL dB(A)
80
70
60
50
40
63
125
250
500
1000
2000
4000
8000
FREQUENCY Hz
Some examples of typical sound levels in dB(A) are shown in Figure 2.3 below. All further
reference to noise levels in these Guidelines will be in dB(A).
Figure 2.3 The level of common sounds on the dB(A) scale
140
Threshold of pain
120
Jet aircraft, 250 metres overhead
100
Hazard to hearing from
continuous exposure
Freight train at 40 km/h,7 metres away
Large truck at 40 km/h,7 metres away
80
Car at 60 km/h, 7 metres away
Communication starts
becoming difficult
60
Busy office
40
Quiet bedroom
20
Threshold of hearing
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DPTI Road Traffic Noise Guidelines
2.5
TYPES OF ROAD NOISE
There are two types of road traffic noise:
(a) from ‘bulk’ traffic flow (i.e. a reasonably continuous stream of vehicles), and
(b) from individual noisy vehicles.
The first occurs on busier roads and manifests itself as a continuous hum or backdrop of
noise, although it can have peaks and troughs according to the traffic flow. It is the
aggregate noise of all the vehicles in the traffic stream.
The second is produced by single vehicles (typically a high-revving motorbike, a car with a
modified exhaust system, or a commercial vehicle’s exhaust brakes) and can occur
anywhere and at any time. This may be loud enough to rise above bulk flow traffic noise
and can be extremely disruptive, particularly at night in quiet residential areas where sleep
can be disturbed.
Although measures can be taken to protect the community against both types, the second
is by far the harder to deal with because of the random nature of occurrences, and can
only be controlled by vehicle design requirements and in-service monitoring of these
requirements. These Guidelines essentially deal with bulk flow traffic noise resulting from
normal operation of the road system.
2.6
FACTORS INFLUENCING ROAD TRAFFIC NOISE GENERATION
Individual vehicle noise is a combination of noises produced by:

the engine;

the transmission;

the exhaust;

the interaction of tyres and road pavement;

air turbulence; and

body and load rattles.
At lower traffic speeds (typically less than 60 km/hr), engine and exhaust noise tend to
dominate. Tyre noise is a component of vehicle noise which significantly increases with
speed. Studies suggest that at speeds between 30 and 50 km/hr, tyre noise of cars is
increased to a level which dominates the overall vehicle noise. For trucks, this ‘cross-over’
point tends to occur between 40 and 80 km/hr.
Given the increasing stringency of vehicle design regulations on engine and exhaust
emissions, tyre noise is increasingly becoming the major factor influencing overall traffic
noise. The tyre noise component is highly dependent on tyre / pavement design and on
vehicle speed. For heavy vehicles the exhaust outlet location is often elevated, which
tends to increase the spread of noise. Air turbulence is not usually important, even at
highway speeds.
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DPTI Road Traffic Noise Guidelines
Figure 2.4 Passenger car noise sources at speeds below 70 km/h (ARRB, 1998a)
27%
34%
Exhaust Systems
Air Intake System
Tyres
9%
Engine
30%
Apart from individual vehicle noise, there are five main factors upon which the level of
traffic noise depends:

traffic volume;

traffic speed;

traffic composition (i.e. the number of commercial vehicles);

the road gradient, and

the pavement surface type and texture.
A change in noise levels may occur if one, or more, of the above factors change. In
addition, there are six major factors which influence the propagation of traffic noise:

the road profile (at grade, depressed or elevated);

the distance from the source to the reception point;

the nature of the ground between the source and the reception point;

the angle of view of the traffic stream from the reception point;

the presence of screening (by fences, earth mounds, barriers or buildings), and

meteorological effects, particularly wind strength and direction.
With the exception of the meteorological effects (refer Section 5.4.4), attention can be paid
to all of the above factors in order to reduce the impacts of road traffic noise.
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DPTI Road Traffic Noise Guidelines
2.7
NOISE DESCRIPTORS
There are two descriptors commonly used to describe road traffic noise which varies over
time. These are L10 and Leq.
The noise descriptor L10 refers to the noise level which is exceeded for 10% of the time in
a given measurement period, and corresponds to the average of the upper noise levels.
In Figure 2.5 below, which shows typical noise level variations over a one hour
measurement period, L10 is the noise level which is exceeded for 6 minutes (10% of one
hour).
The noise descriptor Leq (the equivalent noise level) refers to the value of a steady noise
that would have the same acoustic energy as the varying noise, over the same time
period. Figure 2.5 below also shows the Leq level.
The descriptor L10 is used by some organisations as the descriptor for traffic noise. The
descriptor Leq has now replaced L10 as the commonly used descriptor. Generally, L10 is
around 3 dB higher than Leq, although this difference varies.
Figure 2.5 Common Road Traffic Noise Descriptors.
0.5 minutes
2 minutes
1.5 minutes
2 minutes
LIO
NOISE
LEVEL
Leq
60 minutes
2.8
NOISE MITIGATION MEASURES
There are several ways in which the impacts of road traffic noise can be reduced, the
main ones being (also Refer Figure 2.6):
(a) at the source, by controlling the noise emitted by the vehicle;
(b) along the transmission path, by reducing (attenuating) the noise level as it
travels from the source to the reception point by providing intervening barriers
or buffer zones; and
(c) at the reception point itself, by means of a barrier, building location and
architectural design details to reduce the transmission of noise into the interior.
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DPTI Road Traffic Noise Guidelines
2.8.1
Noise control at the source
Noise control at source is the most effective and equitable way of reducing the impacts of
road traffic noise. This is accomplished by means of the relevant Australian Design Rules
which stipulate the amount of noise various classes of new vehicles are permitted to emit
under certain conditions. Although there are moves to make the rules more stringent, this
can only be done slowly in line with progress in vehicle technology and the attendant cost
penalties. Control at source is however, the most effective way of reducing both bulk flow
noise and individual vehicle noise.
The Department participates in national forums which formulate and administer the
Design Rules and actively encourage and support related research and development of
quieter vehicles.
Other measures include travel demand management initiatives, ensuring the smooth flow
of traffic by reducing vehicle stop / starts and adopting low noise pavement types.
2.8.2
Noise control along the transmission path
Control along the transmission path is the main way that traffic noise impacts can be
reduced at a project level and it is to this area that these Guidelines are primarily directed.
Measures include:
2.8.3

initial route location (away from houses etc);

providing distance between the source and the receiver within the road corridor
such as wide areas of grassed or planted land to absorb noise. There is an
inverse square relationship between sound intensity and distance. Noise will be
reduced by 3 dB if the distance from the source is doubled;

placing the road in cut (where practical) to shield adjacent receivers from noise;

constructing mounds, barriers or fences to shield residences by creating ‘shadow
zones’.
Noise control at the receiver
Control at the reception point can be achieved by

locating and siting the building away from the noise source;

putting the more noise-sensitive rooms in the areas least exposed to the traffic
noise; and

by architectural acoustic treatments such as thick or double glazing, solid doors,
and noise insulation of ceilings, walls and floors.
Planning Authorities can reduce or avoid potential problems with traffic noise by means of
the appropriate zoning of land adjacent to arterial roads, and through ensuring acoustic
issues are addressed in development and building controls. Further information is
available in Reducing Noise and Air Impacts from road, rail and mixed land use – A Guide
for builders, designers and the community.
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DPTI Road Traffic Noise Guidelines
Figure 2.6 Ways of controlling traffic noise
(a) control at source
(b) control along transmission path
(c) control at reception point
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DPTI Road Traffic Noise Guidelines
3 ASSESSMENT PROCESS
3.1
3.1.1
SCOPE OR APPLICATION OF THE GUIDELINES
Scope Definition
Minimising the impacts of road traffic noise should be an objective of any project involving
the construction of new or substantially upgraded or redeveloped roads adjacent to noise
sensitive receivers. Noise treatments as outlined in these Guidelines should normally be
considered under the following circumstances.
New Road

A ‘new’ road where no road previously existed.
For example the Northern Expressway
Redeveloped Road

A substantial widening or realignment of an existing road.

An alignment or realignment producing noise at a receptor from a different
direction that makes a ‘significant’ contribution to existing noise.

A substantial widening or realignment of an existing road that requires the
demolition of building structures or existing roadside noise walls that results in
receivers previously shielded from traffic noise becoming exposed.

A change in the function of a road that results in a ‘significant’ increase in received
noise levels. For example a Local Road being upgraded to an Arterial Road as part
of a heavy vehicle by-pass project. This is typically associated with re-routing
heavy vehicles along an existing road without substantial widening or realignment.
Noise treatment would not normally be considered in the following circumstances.
3.1.2

Upgrading or treating of road surfaces for maintenance, except where that road
surface has been specifically placed as part of a noise treatment package, in
which case a similar performing surface should be used.

Minor upgrading work such as realignment of an intersection, or creation of a left
turn lane, unless it is part of a major upgrade.

Noise sensitive receivers located outside of the defined Noise Assessment
Boundary to which these Guidelines are applied (Refer to Section 5.3).
Noise Sensitive Receivers
Noise sensitive receivers include:
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
Existing dwellings in a zone where dwellings are contemplated as defined by the
relevant Development Plan;

Aged care facilities;

Hospital wards;

Caravan parks that accommodate existing long term residential use;

Churches/places of worship (where reasonable and practicable on a case-bycase basis);
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DPTI Road Traffic Noise Guidelines
3.1.3

The impact of traffic noise on parks should be considered on a case-by-case basis
with protection considered for areas used for passive recreation; and

The impact of traffic noise on existing educational institutions, childcare centres
and kindergartens should be assessed on a case-by-case basis for daytime criteria
only and only to protect teaching areas. Teaching areas within schools may
include an outdoor space provided there are no alternative quiet locations for that
space.
Noise Catchment Areas and Grouping Receivers
Noise level predictions should be undertaken for each noise sensitive receiver. However,
in relation to determining noise mitigation requirements, noise sensitive receivers may be
considered on an individual basis or grouped where there is similar exposure to noise.
The intent of grouping receivers is to ensure a common assessment or mitigation
approach for those receivers that have a similar exposure to noise to provide a more
reasonable and practical approach.
Where individual receivers are grouped together, they are referred to as a Noise
Catchment Area under these Guidelines. A noise catchment should include:

at least three noise sensitive receivers in close proximity; and

all receivers are exposed to similar noise levels (i.e. typically within 2 dB(A) of
each other) and are usually at a similar proximity to the noise source; and

a logical delineation of the catchment area (e.g. by topography, cuttings, setbacks,
road, rail or utility corridors, breaks in the landscape etc.).
When grouping noise sensitive receivers into a noise catchment area, the decision to
investigate or provide noise mitigation should be based on the extent of criteria
exceedances across the group. If mitigation is required, applying a consistent approach
across the catchment and wider project is advised.
For example, if the predicted noise levels across a noise catchment area indicate
compliance with the noise assessment criteria at more than two-thirds of receivers, and
the remaining receivers have minor exceedances of 2 dB(A) or less, then no further noise
mitigation is required to be considered. In a similar way, each storey and facade of a
multi-storey apartment block may be considered individually or managed as a group.
Further consideration should be given to any individual receivers that exceed the noise
assessment criteria (refer Section 3.2) by more than 2 dB(A).
3.1.4
Responsibility for Mitigating Traffic Noise
The Department is responsible for the provision of noise mitigation measures which
protect developed noise sensitive receivers within the defined Noise Assessment
Boundary for a new or redeveloped road project.
Noise mitigation measures will also be provided to protect any noise sensitive receivers
for which a Development Consent under the Development Act 1993 has been granted
before the date that the road project was publically announced.
It is the property owner or developer’s responsibility to provide noise mitigation measures
for developments submitted for planning approval after a road project has been publicly
announced. Developments should comply with provisions in the relevant Development
Plan and where applicable the requirements of the Minister’s Specification SA 78B.
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3.2
NOISE ASSESSMENT CRITERIA
3.2.1
Noise Descriptors
The noise descriptors in the table below refer to the energy averaged equivalent (Leq)
noise level over each period, and are defined as:
3.2.2
Time Period
Descriptor
Day (7am to 10 pm)
dB(A)Leq (15hr) or LAeq day
Night (10pm to 7 am)
dB(A)Leq (9hr) or LAeq night
Noise Criteria
The following table sets out the Noise Criteria applicable for either ‘new’ or ‘redeveloped’
road projects (Refer Section 3.1.1). The application is also explained in Figure 3.1.
Noise Criteria(1) – dB(A)Leq
Project Type
New Road
Redeveloped
Road
Applicable situation
Day
Night
55
50
Existing receivers affected by
noise from a redeveloped road
60
55
Existing receivers affected by
noise from a redeveloped road
and where demolition of building
structures or existing roadside
noise walls(2) results in receivers
previously shielded from traffic
noise becoming exposed.
57
52
Existing receivers affected
noise from a new road
by
Note:
(1) Assessed at 1 metre from the facade (refer Section 3.2.5).
(2) Does not include property fencing.
Note that the redeveloped road criteria are reduced by 3 dB in situations where a sensitive
receiver may experience a perceived increase in noise exposure due to the demolition of
adjacent building structures or existing roadside noise walls (that are not replaced).
It is typically applicable in situations where the front rows of houses or an existing noise
wall has been demolished to make way for the project, thereby exposing the rows behind
to a further increase in noise. The reduced Noise Criteria is not applicable in situations
where an existing property fence has been removed.
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3.2.3
Relative Increase Criterion
A large increase in existing noise can cause a major change to the acoustic environment
of a location. Under these guidelines, this is assessed using a Relative Increase Criterion
(RIC). The application is also explained in Figure 3.1.
The Relative Increase Criterion (RIC) should be applied to receivers where it is more
stringent than the new or redeveloped road criteria (refer Section 3.2.2). This would
generally only occur where a new road is being developed in an area where there is no or
low levels of existing traffic noise. In this instance only the RIC needs to be applied to the
receiver. Note that the lowest assessable existing noise level is 30 dB(A)Leq.
The most stringent criterion of either the day or night time period is applicable. The RIC is
defined as:
3.2.4
Time Period
Descriptor
Day (7am to 10 pm)
Existing LAeq day + 12 dB
Night (10pm to 7 am)
Existing LAeq night + 12 dB
Transitioning Between Noise Catchment Areas with Different Criteria
A criteria transition will need to be considered when a project spans across multiple noise
catchments that have different noise assessment criteria. In these situations, the method
of criteria transition can either be a gradual or immediate transition depending upon how
logical the delineation of the noise catchment area is (e.g. delineation by topography,
cuttings, setbacks, road, rail or utility corridors, breaks in the landscape etc.).
For example:
3.2.5

A local road extends perpendicular to a ‘redeveloped’ road project between two
noise catchment areas, namely Catchment A and Catchment B. Catchment B has
had the front row of houses demolished due to a shift in the road alignment, while
Catchment A houses are untouched. In this case an immediate transition is likely
to be the preferred approach i.e. where the Noise Criteria changes immediately
from 55 dB(A) at Catchment A to 52 dB(A) at Catchment B.

A ‘new’ road project merges into a ‘redeveloped’ road project. In this case a
gradual criteria transition from 50 dB(A) (New Road) to 55 dB(A) (Redeveloped
Road) in 1 dB(A) steps is likely to be the preferred approach.
Noise Assessment Location
Noise levels are to be predicted or measured outside at a position one metre from the
most exposed window at a height of 1.5 metres above floor level for each noise sensitivereceiver building facade. Noise levels at this location are influenced by reflections from the
building facade, and all predictions are to include a facade reflection factor of +2.5 dB.
If noise levels for individual properties are measured at locations not subject to reflections
from the building facade, they should also be subject to an adjustment factor of +2.5 dB to
ensure that the comparison of noise levels against the noise assessment criteria are
consistent. Each floor level of a multi-storey building should be considered separately
when predicting noise levels for comparison against the noise assessment criteria.
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3.2.6
When should Noise Mitigation be considered?
Receivers with exceedances (or residual exceedances) of the Noise Criteria or Relative
Increase Criterion (RIC) should be assessed as outlined below and in Figures 3.1 and 3.2
to determine if they are eligible for noise mitigation.
Noise levels and noise increases should be assessed at each affected receiver facade
noting that the largest noise increase may not be at the noisiest facade.
The receiver’s eligibility for consideration of noise mitigation should be based on the
change in noise level due to operational changes associated with the proposed road
design at the project-opening year. For this comparison, it is important that project related
noise barriers are not included, however road design measures such as road surface type
and jersey barriers should be included.
Once a receiver is eligible for consideration of noise mitigation, the mitigation measures
should then be designed to meet either the Noise Criteria or the RIC (whichever is the
most stringent) for the predicted traffic volume 10 years post project opening, where
reasonable and practicable.
When evaluating if a receiver is eligible (at the project-opening year), one of either the
following tests must be satisfied:
(a)
is the predicted noise level greater than the Relative Increase Criterion, if it is the
most stringent noise assessment criteria (refer Section 3.2.3)?
(b)
is the project predicted noise level more than 2 dB(A) (i.e. ≥ 2.1 dB(A)) above the
existing predicted noise level for the same year (or an earlier year as elected by
the project) and above the Noise Criteria?
(c)
is the predicted noise level greater than or equal to 5 dB(A) (i.e. ≥ 5.0 dB(A))
above the Noise Criteria?
The above tests provide for a reasonable and practicable approach to identifying eligible
receivers through managing large relative increases in noise, high noise exposure
situations, as well as small noise increases not perceptible to the human ear (i.e. less than
2 dB(A)).
3.2.7
Flowchart of Assessment Process
The flowchart provided on the following pages (Figure 3.1 and 3.2) outlines noise the
assessment process to be undertaken under these Guidelines. It applies to each noise
sensitive receiver as outlined in Sections 3.1.2 and 3.1.3.
Note that selecting the most reasonable and practicable noise mitigation measures may
be an iterative process reflecting a mixture of treatment options.
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Figure 3.1 Noise Assessment Criteria flow chart
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Figure 3.2 Noise Mitigation flow chart
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4 NOISE MITIGATION DESIGN
4.1
ROAD DESIGN
Road design measures may include adjustment to the vertical and horizontal alignments,
low noise pavement surfaces, road gradient modifications, speed limit reduction, traffic
management measures, New Jersey style barriers and the like.
These measures should only be implemented where there are no significant impacts on
other road design considerations such as cost, access, security, community acceptance
and safety.
Although the noise reducing road design measures are to be considered as the first
stage of the acoustic assessment, they should be revisited during consideration of
subsequent stages such as barrier design and house treatment determination. That is,
the selection of the most cost effective mix of treatment is expected to require an
iterative design process across all stages.
For example, when determining a barrier height, if further noise reduction is required to
achieve a noise benefit, it may be more cost effective to change the pavement type than
increase the barrier height. However when low noise pavement surfaces are used for
noise attenuation there must be a commitment to continue the use of these surfacings in
future maintenance of the road.
4.2
NOISE BARRIERS
A guide to reasonable heights for roadside noise barriers and acoustic fences are
detailed in the following table.
Proposed Barrier Location
Property boundary
Access to property is through the barrier
Property boundary
Property access is from another road
Within road reserve
Height
Up to 2.4 with solid gates(1)
Up to 4m(2),(3)
Up to 7m(3)
Notes:
(1) Fences with gates may be constructed to a height above 2.1 metres as long as the gate is
designed so as not to degrade the acoustic performance of the fence and the functionality of
the gate is acceptable.
(2) Individual project circumstances may result in a project specific requirement to alter the
height above 4m.
(3) Barriers that are greater than 3.5m in height must take into account factors such as the noise
reduction benefit versus cost, practical construction limitations, visual amenity and
overshadowing issues. Generally, these barriers should be set back from an adjacent
property boundary taking into account the ability to maintain the space and the potential to
reduce the impact of the barrier by using clear barrier material.
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Where acoustic fences are to incorporate gates for access reasons, the fence should not
normally be constructed to a height greater than 2.1 metres as the gate may degrade the
acoustic performance of the fence and be difficult to open. However, a higher fence
incorporating a gate may be constructed where it can be demonstrated that the gate will
not degrade the acoustic performance of the fence and the functionality is acceptable
(e.g. the gate is automated).
Safety aspects for access to the property, such as ability to open the gate with the
vehicle off of the road should also be considered, i.e. situations that would present a
danger for the resident to stop and exit a vehicle on an arterial road in order to open the
gate manually.
4.2.1
Barrier Design
This section describes the objectives/process to be used to design noise barriers for
receivers that have been identified as eligible for consideration of noise mitigation under
Section 3.2.6. The objectives to be considered during barrier design are as follows:
(a) Communities should receive reasonable and equitable outcomes.
(b) Noise mitigation should be designed to reduce noise levels to the criteria.
(c) Noise barrier evaluation processes must:
-
Give preference to reducing outdoor noise levels and the number of property
treatments.
-
Provide efficient barrier heights and extents without disregarding lengths of
effective noise barrier in front of eligible groups of receivers.
-
The average barrier length per property should typically be restricted to 50
metres in recognition that appropriate property treatments (refer Section 4.3)
for dwellings more than 50 metres apart represent a significantly more cost
effective solution than the construction of a barrier.
(d) Noise mitigation should be evaluated and installed where reasonable and
practicable.
Noise barrier designs can vary in height along the barrier length, subject to urban design
and community views. However if a barrier is to vary in height along its length it must
achieve an equivalent noise outcome for the community as a constant height noise
barrier.
Before assessing barrier height the location of the barrier should be reviewed to ensure
that it provides the best opportunity to use the topography and road geometry to
maximise shielding.
4.2.2
Noise Barrier Benefit
As a guide noise walls or mounds are considered to be a reasonable noise mitigation
option where they are capable of providing an insertion loss of:
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For noise barriers more than 3 m high, the insertion loss must be more than 5
dB(A) at the most affected receiver, or

10 dB(A) at representative receivers for heights above 5 metres and up to 7
metres high.
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When considering the above insertion loss requirements, the following provides
additional clarification:
4.2.3

Where a location exceeds the noise assessment criteria by less than 5 dB(A) this
could lead to designing to achieve an insertion loss of less than 5 dB(A). Under
these circumstances, where two-thirds of the noise sensitive residences no longer
require property treatment a noise barrier should not be abandoned because it did
not provide 5 dB(A) insertion loss.

Small barriers that are low cost to install, such as jersey barriers, but do not
provide an insertion loss of 5 dB(A), may also form part of an overall noise
mitigation strategy.

Where noise barriers greater than 5 metres in height do not provide 10 dB(A) of
noise reduction, additional consideration needs to be given to the number of
receivers that benefit, any unusual topography and whether the barrier placement
could be improved. If it is not reasonable to provide a barrier with height above 5
metres then lower heights should be considered.
Barrier Materials
A noise barrier should generally be constructed from the most cost effective materials
that will not significantly degrade the acoustic performance of the barrier. In relation to
residential fences the material should generally be Colorbond or equivalent or if there is
an existing fence it should be replaced with similar materials to existing. However, other
criteria such as maintenance, longevity, existing fencing, amenity, urban design and
streetscape issues, Council requirements in relation to the character of the area and
heritage issues may also need to be considered in the material selection process.
It may be possible for individual land owners to upgrade the barrier construction on their
property, over that offered by the Department, by paying the difference in cost, provided
that the acoustic performance is not compromised.
Refer to the Noise Mitigation Manual for more information on acceptable barrier
materials.
4.3
PROPERTY TREATMENT
This section describes the process to be used to design property treatments for
receivers that have been identified as eligible for consideration of noise mitigation under
Section 3.2.6. Property noise mitigation measures may replace road corridor mitigation,
subject to a reasonable and practicable assessment, and only in the following
circumstances:
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Isolated single residences or isolated groups of closely spaced residences.

Where the affected community expresses a preference for at-property treatment
and the cost is less than a combination of a barrier and at-property treatment.

Where noise barriers cannot achieve the level of noise mitigation (insertion loss)
required.

Where other noise mitigation measures have been shown not to be reasonable or
practicable.
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These treatments are generally limited to facade treatments to habitable spaces.
However on a case-by case basis the installation of acoustic screening close to the
dwelling may be considered in lieu of facade treatments.
4.3.1
Facade Treatment Criteria
Under these guidelines, facade treatments to habitable spaces relate to National
Construction Code (NCC) Class 1, 2, 3 and 4 buildings and 9c aged care buildings (refer
to Appendix A for NCC building classifications). Note that transportable buildings are not
eligible for treatment unless it can be demonstrated that upgrade of the facade glazing is
likely to result in a noticeable noise reduction for the resident.
Noise sensitive receivers that do not fall under the NCC categories are typically
assessed on a case-by-case basis (e.g. educational institutions or hospital wards). In
these instances, the current revision of Australian Standard AS 2107 – Acoustics –
Recommended design sound levels and reverberation times for building interiors may be
referred to as the basis for acoustic design.
If receivers have been identified as eligible for consideration of noise mitigation under
Section 3.2.6, the facade treatment package is determined from the table below.
Habitable Space
Applicable Facade Treatment Package for Noise Levels
above the Noise Criteria or Relative Increase Criterion
>2 - 5 dB(A)
6 - 9 dB(A)
10 - 13 dB(A)
>14 dB(A)
Bedrooms
1
2
3
4
Other habitable rooms
n/a
1
2
3
Notes:
(1) Predictions must be at 1 metre from the facade, include the 2.5 dB(A) facade reflection
correction and rounded to the nearest decibel to ensure correct determination of the Sound
Exposure Category.
(2) For Facade Treatment Package 3 and 4, alternative ventilation in addition to openable
windows must be provided in accordance with the requirements of Section 4.3.4.
(3) Non-habitable rooms include walk-in wardrobes, en-suites and enclosed kitchens. However,
where these spaces are part of an open plan arrangement with adjoining habitable rooms,
such as a living/dining area or bedroom, they need to be treated as part of the habitable
room.
(4) Treatments to residential dwellings will be restricted to bedrooms, studies, living, dining and
kitchen areas that have windows or doors in the façade being treated. Corridors, laundries,
bathrooms, garages, sheds and workshops will not be treated.
(5) When the Noise Criteria is less than 50 dB(A), treatments to residential dwellings will be
restricted to bedrooms that have windows or doors in the façade being treated.
For example, if the predicted outdoor noise level at 1 metre from the most exposed
facade is 63 LAeq night, the Facade Package Treatment for a redeveloped road criteria of
55 dB(A) is ‘2‘ for bedrooms and ‘1’ for other habitable rooms.
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4.3.2
Facade Treatment Packages
The following table outlines the applicable Facade Treatment Package with reference to
the applicable package number obtained from Section 4.3.1.
Note that the Facade Treatment Packages are a deemed to satisfy solution to meet the
requirements of these Guidelines. An alternative solution is not required to be designed
by an acoustic engineer. However, an acoustic engineer may design alternative
treatment options to achieve an equivalent acoustic performance to the specified
package treatments.
Facade
Treatment
Package
Acoustic Performance Requirements
Windows and external glass doors
Window = RW + Ctr 31
For example, the acoustic equivalent of an existing window system
incorporating 3 mm thick glass, with the addition of a 4.5 mm thick acrylic
panel separated by a 150mm air gap or a single window system
incorporating at least 6 mm thick laminated glass.
Door = RW + Ctr 28
For example, the acoustic equivalent of a glass door system
incorporating at least 6 mm thick laminated glass.
Acoustic Seals
1
In order to achieve the acoustic performance, acoustic grade seals will
need to be incorporated into the above secondary or replacement
window or door systems.
External doors other than external glass doors
Door = RW 30
For example, the acoustic equivalent of a solid timber core door with
acoustic grade seals to head and jamb.
External Flanking Paths
Inspect the facade for external noise flanking paths that could potentially
degrade the installed treatment. Rectify where reasonable and
practicable. For example, block internal wall vents that have a direct path
to the external wall facade. Note that external wall or floor cavity vents
required for moisture control do not need to be treated.
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Facade
Treatment
Package
Acoustic Performance Requirements
Windows and external glass doors
Window = RW + Ctr 34
For example, the acoustic equivalent of an existing window system
incorporating 3 mm thick glass, with the addition of a 10 mm thick acrylic
panel separated by a 100 mm air gap or a single window system
incorporating at least 10 mm thick laminated glass.
Door = RW + Ctr 31
For example, the acoustic equivalent of a sliding glass door system
incorporating at least 10 mm thick laminated glass.
Acoustic Seals
2
In order to achieve the acoustic performance, acoustic grade seals will
need to be incorporated into the above secondary or replacement
window or door systems.
External doors other than external glass doors
Door = RW 30
For example, the acoustic equivalent of a solid timber core door with
acoustic grade seals to head and jamb.
External Flanking Paths
Inspect the facade for external noise flanking paths that could potentially
degrade the installed treatment. Rectify where reasonable and
practicable. For example, block internal wall vents that have a direct path
to the external wall facade. Note that external wall or floor cavity vents
required for moisture control do not need to be treated.
Windows and external glass doors
Window = RW + Ctr 37
For example, an acoustically rated single or double-glazed window
system that can achieve the acoustic performance requirement. It is
likely that a new window system will be required.
3
Door = RW + Ctr 34
For example, an acoustically rated single or double-glazed door system
that can achieve the acoustic performance requirement. It is likely that a
new door system will be required.
Acoustic Seals
In order to achieve the acoustic performance, acoustic grade seals will
need to be incorporated into the window or door system.
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External doors other than external glass doors
Door = RW 32
For example, the acoustic equivalent of a solid timber core door of not
less than 28 kg/m2 surface density, acoustic grade seals around the
head and jamb acoustically equivalent to Kilargo IS1212/1515 or Raven
RP120/150 (batwing seals) and a dropdown seal at the bottom
acoustically equivalent to Kilgaro IS8090si or Raven RP38.
Double doors to also have meeting stile seals acoustically equivalent to
Kilargo 2xIS7060si or IS7071si, or Raven 2xRP16 or 2xRP71Si.
Roof and Ceiling
3 (cont.)
Provide insulation batts to ceiling cavity if no insulation present on
inspection.
External Flanking Paths
Inspect the facade for external noise flanking paths that could potentially
degrade the installed treatment. Rectify where reasonable and
practicable. For example, block internal wall vents that have a direct path
to the external wall facade. Note that external wall or floor cavity vents
required for moisture control do not need to be treated.
Ventilation
Mechanical ventilation is required in accordance with Section 4.3.4 and
should be designed such that the facade acoustic performance is not
degraded.
Package 3 architectural treatments (above) are applicable.
4
An offer for voluntary acquisition of the property may also be considered
on a case-by-case basis.
The following should be considered before and during the application of facade
treatments:
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Only facades of habitable rooms being used at the time of the project will be
treated. Future renovations (not yet approved by Council) that will change the use
of a space will not be considered during the treatment process.

Facades of rooms that are not habitable and/or in a considerable state of disrepair
will not be treated.

Facades that contain asbestos can be treated under the provision that the owner
pays for cost of asbestos removal and clean up.

Electrical wiring that is considered not safe to supply a mechanical ventilation
system can be repaired at the owners cost.

Architectural treatments may be substituted with alternative treatments at the
discretion of Departmental representatives, where the alternative provides an
equivalent level of noise reduction.

While due care must be taken in the design and selection of acoustic treatments
the Department makes no guarantee that any particular internal noise level will be
achieved.
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4.3.3
Facade Treatments to Noise Sensitive Non-Habitable Spaces
Noise sensitive non-habitable spaces relate to educational institutions, childcare centres
and kindergartens. Facade treatments to these receivers will be determined on a caseby-case basis using AS/NZS 2107:2000 (or current issue).
4.3.4
Mechanical Ventilation
The provision of mechanical ventilation is required to be considered for Facade
Treatment Packages 3 and 4, where no suitable existing mechanical ventilation exists.
Note that mechanical ventilation is not required for Facade Treatment Packages 1 and 2,
although may be provided at the discretion of the Department where it is required under
the Building Code.
Where a mechanical ventilation system is required, the ventilation system must be
installed:
4.3.5
(a)
In accordance with the Building Code of Australia and complying with AS 1668.2
- The use of mechanical ventilation and air-conditioning in buildings, and
(b)
The relief air path/s should be fully ducted to allow operation of the system with
windows and external doors closed, and
(c)
The fresh air (or make up air) inlets and exhaust air outlets shall be at a point on
the building furthest from the road corridor where practicable.
Acoustic Screening
As an alternative to facade treatments (for eligible receivers), property treatments can
also utilise acoustic screening situated close to the dwelling for the purpose of shielding
an outdoor entertainment area (and associated facade) if this is considered a preferred
approach. Acoustic screening is considered on a case-by-case basis where practical
and in consultation with the resident.
Acoustic screening should be treated in the same way as a property boundary fence in
terms of height limits, materials and value for money insertion loss performance.
4.4
NOISE MITIGATION GENERAL NOTES
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Under no circumstances will the Department offer monetary compensation to
property owners instead of noise mitigation treatments.

A property owner can reject offered noise mitigation treatments but must sign a
Statement of Agreement to Refuse Noise Mitigation Treatment.

Alternative treatments providing less acoustic attenuation may be provided where
the property owner prefers the alternative and understands they will not be
provided with an equivalent level of noise mitigation. In this case, a waiver must be
signed by the property owner. Refer to the Noise Mitigation Manual for information
on suitable alternative treatments.

Mitigation treatments should consist of constructions and materials that are
deemed by the Department to be reasonable and practicable. If the property owner
desires an alternative construction or material, any additional cost will be the
responsibility of the owner.
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5 PROCESS FOR ASSESSING ROAD TRAFFIC NOISE
5.1
GENERAL
Noise impacts and mitigation measures need to be identified and implemented throughout
the project delivery process from the initial strategic and concept planning stages through
to design and construction. Noise mitigation should be considered as an integral part of
the planning and design process and not an “add-on” once the preferred solution has
been developed.
For the ground floor residential dwellings that are eligible for consideration of noise
mitigation measures, mitigation should be designed such that future traffic noise levels
(usually 10 - 15 years from opening) achieve the Noise Criteria where reasonable and
practicable. Where it is not reasonable and practicable to achieve the criteria, Facade
Package Treatments to the individual dwelling should be provided in accordance with the
process outlined in Section 4.3.
For the upper floors of any multi-story residential building, only facade treatments will be
considered. For non-residential noise sensitive receivers, where the property is not
normally used at night times, only the day time criteria need be applied.
Mitigation measures should protect exposed building facades and areas likely to be used
for outdoor entertainment. They would not normally be provided to protect areas primarily
used for parking or storage.
The process for assessment of road traffic noise is outlined below:
(a)
give formal notification of the road project;
(b)
obtain the project road design and identify traffic noise variables – this includes
data on pavement surface type, gradients, traffic volume and composition (both
day and night), traffic speed, traffic control devices and adjacent property details;
(c)
predict the existing road traffic noise levels and compare to noise logging results
representative of the existing traffic noise environment. From this, validate the
noise model using known corrections to adjust for Australian conditions. Calibrate
the noise model as required in consultation with the Department or
representatives. Calibration corrections from previous project verification
assessments should also be considered where available;
(d)
predict the future existing road traffic noise levels at the project-opening year;
(e)
predict the future project road traffic noise levels at the project-opening year
without any project related noise barriers;
(f)
determine the Noise Assessment Boundary in accordance with Section 5.3;
(g)
identify all noise sensitive receivers within the Noise Assessment Boundary and
compare the predicted noise level differences between the existing and project
model situations at the project-opening year and identify those noise sensitive
receivers that are eligible for consideration of noise mitigation (refer Section 3.2.6);
(h)
group into noise catchment areas where relevant (i.e. groups of receivers with
similar noise exposure);
(i)
predict the future project traffic noise levels (10 years into the future) and design
reasonable and practicable noise mitigation measures in accordance with Section
4 and Section 5.5.1 based on this modelling scenario;
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5.2
(j)
for a planning and concept design phase assessment, document the noise
assessment in the Planning Assessment Report, Environmental Report or
Environmental Impact Assessment Report. Note that the documentation of noise
mitigation during this phase should be focused on non-specific treatment options to
allow design flexibility during the detailed design and construction phase of a
project;
(k)
for a detailed design and construction phase assessment, a Noise Mitigation Plan
should be prepared that is suitable for consultation with the wider project team,
Councils, the community and other key stakeholders with an interest on the
proposed noise mitigation strategy. The Noise Mitigation Plan should then be
refined over the detailed design phase until it is approved for Issue For
Construction (IFC);
(l)
post construction, verification of the noise model predictions and implemented
noise mitigation measures should be carried out in accordance with Section 5.7.
FORMAL NOTIFICATION OF A ROAD PROJECT
For purposes of establishing whether a noise sensitive receiver should receive noise
mitigation measures as part of a road project it is necessary to establish if the
development of the land use has received development consent under the Development
Act 1993 prior to the formal notification of the road project. Therefore, formal notification
of the road project should be given by the Department at an appropriate stage in the
planning phase.
5.3
NOISE ASSESSMENT BOUNDARY
The extent of the Noise Assessment Boundary is defined as follows:
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The location (project footprint) in which physical works associated with the road
project occur and may extend to close-by landmarks or cadastral boundaries to
provide a logical endpoint. Note that physical works does not include pavement
reseals.

The width either side of the project is to be set to the extent where the predicted
noise level without noise mitigation equals the lowest applicable noise assessment
criteria. Note that the width may be reduced where the noise levels from the
project contribute no more than 2.0 dB(A) to the total traffic noise level, for
example, where the assessed road project intersects other Arterial Roads.

In any case, the width either side of the project should be no more than 600
meters from the centre line of the outermost traffic lane on each side of the road
project. This distance is based on the limit of accuracy of current road traffic noise
models.

The Noise Assessment Boundary should be defined using property boundaries
obtained from a current cadastral map.
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5.4
MODELLING ROAD TRAFFIC NOISE
An appropriate road traffic noise prediction software package that is acceptable to the
Department must be used for all road traffic noise assessments. The Department will
accept the use of software that correctly implements the United Kingdom, Department of
Environment (1988), Calculation of Road Traffic Noise (CoRTN) algorithm. Other models
such as the US Department of Transportation, Federal Highways Administration (FHWA)
Traffic Noise Model (TNM) may also be used upon agreement with the Department.
Details of any modelling assumptions including the model calibration or verification
procedure must be included in relevant project documentation.
5.4.1
Noise Model Validation
Validation of the noise model is considered good practice by the Department. This can be
achieved by comparing the measured versus predicted noise levels determined at a
number of representative sites for an existing situation noise model. The model may be
deemed to be validated if the average difference between the measured and predicted
levels is no more than ± 2 dB(A). Any calibration (or correction) factors used in the
modelling process must be clearly documented.
5.4.2
Noise Model inputs
To undertake a detailed investigation, the following information is generally required,
although the requirements will depend on the calculation algorithm being used:
(a)
Traffic flow counts / predictions: The predicted Annual Average Daily Traffic
(AADT) flows for the project and relevant surrounding road network is required.
The AADT data must be separated into the volume percentage occurring over 7
am to 10 pm (day) and 10 pm to 7 am (night), for the existing conditions, at projectopening ‘no build’ and ‘build’ scenarios and 10 years future from project-opening.
Furthermore, the traffic flow percentage splits for the following classifications are
also required:
- Light vehicles (Austroads Classes 1 – 2)
- Heavy Vehicles (Austroads Classes 3 – 12)
(b)
Traffic flow control devices: Details and location of any flow control devices are
required. These may include stop signs, traffic signals, and on-ramp start points.
(c)
Traffic speeds: Statutory sign posted speeds are preferred. Non-statutory speeds
may be used in special circumstances upon agreement with the Department.
(d)
Road design: Details of the road alignment and structures (i.e. bridge, underpass,
jersey barriers etc) in x,y,z CAD format such as DXF, DWG, SHP.
(e)
Topographical features: Details of relative heights, buildings, and landform etc.
are required to carry out the noise predictions.
(f)
Property identification: An identification number for all properties within the
Noise Assessment Area will generally be issued by the Department’s property
group.
(g)
Pavement surface type: Pavement surface type is an important factor in
determining overall traffic noise levels, with different surface types resulting in
either increased or decreased noise levels. Guidance should be sought from
Section 5.4.3 and agreed in consultation with the Department.
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5.4.3
Road surface corrections
The following table details typical values of noise level corrections for different road
surface types, relative to dense graded asphalt. Note that the values in the table should
be used as a guide only, as variations in road texture and porosity may affect the actual
result achieved.
Surface type
Increase (+) / decrease (-) in traffic noise
level relative to DGA
Spray seal, 10 mm or larger
+ 4 dB
Spray seal, 7 mm or larger
+ 2 dB
Dense graded asphalt (DGA)
0 dB
Stone mastic asphalt (SMA)
- 1 dB
Open graded asphalt (OGA)
- 2 dB
For more information on the acoustic performance and durability of alternative road
surfaces, including concrete road surfaces, refer to the Noise Mitigation Manual.
5.4.4
Meteorological Effects
Modelling the effects of various meteorological conditions is not a requirement for traffic
noise predictions, particularly given the capability of current traffic noise calculation
algorithms. Noise predictions under these Guidelines are indicative of the average traffic
noise received over an annual period.
5.5
DEVELOPMENT OF A NOISE MITIGATION PLAN
Should noise modelling of the proposed road design during the design and construction
phase of a project indicate the consideration of noise mitigation, the development of a
Noise Mitigation Plan (NMP) is required.
The NMP should clearly outline the Noise Assessment Area, all noise sensitive receivers,
identified noise catchment areas, and the preferred combination of noise mitigation
measures adopted for the project.
5.5.1
Reasonable and Practicable Mitigation
For all road projects where noise mitigation measures are proposed, it is necessary to
consider what measures are reasonable and practicable. Noise mitigation can be provided
in a range of ways and may be a combination of methods including barriers, dwelling
treatments and road design measures. The mix of treatments should be optimised and
consider the most cost effective for the location.
Selecting reasonable mitigation measures from those that are possible involves judging
whether the overall noise benefits outweigh the overall adverse social, economic and
environmental effects, including the cost of the measure.
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To make such a judgement, consideration may be given to:
(a)
Cost: the cost of installing the mitigation measure, including the cost of materials,
ongoing maintenance costs and any other costs likely to be incurred in scoping
and installing the measure. The cost per dB noise reduction (or insertion loss) is an
important indicator when weighing up the reasonableness of a noise mitigation
measure, and measures that provide no noise reduction benefit should be avoided.
(b)
Type of noise mitigation: consideration of the type of noise mitigation measure.
For example, where practical it is preferable to reduce noise at the source (e.g.
using road design measures) or minimise the transmittal of the noise (e.g. through
road side noise barriers) rather than treat noise at the receiver through property
fencing or architectural treatments.
(c)
Community acceptance: before noise mitigation measures are finalised, the
community’s views should be established and taken into consideration (refer
Section 5.5.2).
(d)
Urban design objectives: consideration of the visual impact, or benefits, of the
noise mitigation measure, as well as shading, safety and security aspects.
(e)
Environmental effects: noise mitigation measures such as roadside barriers and
earth mounds can have environmental impacts themselves which may affect areas
of cultural significance such as heritage buildings, areas of scenic beauty, local
views or significant vegetation.
(f)
Noise Catchment Area approach: refer Section 3.1.3.
The practicability of a mitigation measure relates to engineering considerations of what
can feasibly be constructed and installed:
5.5.2
(a)
Structural: consideration of issues for the noise wall design and installation
issues, including wind, ground conditions etc.
(b)
Access: any impacts that the mitigation measure may have on access to
properties and/or to local roads.
(c)
Safety: safety concerns associated with the mitigation measure. For example,
road safety design requirements (i.e. clear zones, sight distances etc.), CPTED
issues and pedestrian safety.
(d)
Maintenance: consideration of the amount of upkeep needed to maintain the
mitigation measure.
Community Acceptance
Roadside noise barriers or property boundary fences are frequently the most effective
acoustic treatment as they provide protection to outdoor as well as internal living areas.
However in order to achieve the criteria, they might need to be large and out of proportion
to the built environment and so significantly impact upon the aesthetic amenity of an area.
Barriers and fences may also prevent residents enjoying a particular view. Certain works,
such as high domestic fences, might not be permitted by the local planning authority.
Before noise mitigation measures are finalised for a project, consideration of the
viewpoints of the property owners and residents that will receive a noise reduction benefit
is required.
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In the case of high property boundary fences, this should involve individual discussions
with property owners after the development of a proposal for each property, which takes
account of relevant streetscape, urban design and property issues. Mitigation measures
with most support from the community should ideally be adopted where reasonable and
practical.
5.5.3
Noise Mitigation Plan
Once the preferred combination of project noise mitigation measures has been selected, it
should be clearly justified and documented in the NMP and associated Community
Engagement Strategy.
Guidance may also be sought from the Department’s Noise Mitigation Manual..
5.6
DATABASE OF NOISE MITIGATION TREATMENTS
A record of noise treatment including noise walls, fences and property treatments should
be kept to assist in responding to any future queries about the work undertaken, and as a
record of the extent of the arterial network with noise mitigation measures.
The Environmental Group in the Projects Directorate manages this database.
5.7
POST CONSTRUCTION VERIFICATION
For major projects, post construction noise monitoring should be undertaken to verify the
noise modelling predictions and the implemented noise mitigation measures by a suitably
qualified acoustic engineer.
Noise monitoring should be conducted once traffic flows have stabilised, and preferably
within 6 months of project opening. Monitoring of traffic flows and composition should be
undertaken simultaneously with the noise level monitoring. Care should be taken to locate
the noise loggers used for verification away from the traffic counters to minimise tyre noise
influence associated with travelling over the counter wire.
Furthermore, the model calibration factors derived and validated, as part of the verification
process, should be provided to the Department for record keeping. This information can
be used as a valuable resource to inform future projects.
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6. BIBLIOGRAPHY
ARRB Transport Research Ltd (1998) Road Surface Characteristics and Condition: Effects
on Road Users. Research Report ARR314.
ARRB Transport Research Ltd (1998) Overview of Noise and Spray Durability
Characteristics for Open Graded Friction Course.
Australian Building Codes Board, National Construction Code Series Volume One and
Two (Building Code of Australia)
Austroads (2003) AP-G63 03 Guide to the Selection of Road Surfacings.
Austroads (2005) APR277/05 Modelling, Measuring and Mitigating Road Traffic Noise
Berglund, B; Lindvall T, Schwela D, Goh KT (1999) World Health Organization: Guidelines
for Community Noise
Department of Planning, Transport and Infrastructure (2010) Noise Mitigation Manual
Department of Planning, Transport and Infrastructure (2013) Minister’s Specification, SA
78B, Construction Requirements for the Control of External Sound
Department of Planning Transport and Infrastructure (2013) Reducing noise and air impacts
from road, rail and mixed land use – a guide for builders, designers and the community
Department of Planning Transport and Infrastructure Reducing Transport Noise Impacts – A
Guide to Home owners
Environment Protection Authority (1993) Environment Protection Act
Environment Protection Authority (2013) Guidelines for the assessment of noise from rail
infrastructure
Kotzen, B. and English, C. (2009) Environmental Noise Barriers: A Guide to Their Acoustic
and Visual Design, 2nd Edition
Standards Australia (2000) AS 2107 Acoustics – Recommended Design Sound Levels and
Reverberation Times for Building Interiors.
UK Department of Environment (1988) Calculation of Road Traffic Noise
US Department of Transportation Federal Highway Administration (2010) Highway Traffic
Noise: Analysis and Abatement Guidance.
World Health Organisation, 2009, Night Noise Guidelines for Europe, World Health
Organisation, European Region
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APPENDIX A
Classification Summary of Buildings and Structures as defined under the Australian
Building Codes Board (ABCB) National Construction Code.
CLASSES OF BUILDING
Class 1
Class 1a
A single dwelling being a detached house, or one or more attached
dwellings, each being a building, separated by a fire-resisting wall,
including a row house, terrace house, town house or villa unit.
Class 1b
A boarding house, guest house, hostel or the like with a total area of
all floors not exceeding 300m2, and where not more than 12 reside,
and is not located above or below another dwelling or another Class
of building other than a private garage.
Class 2
A building containing 2 or more sole-occupancy units each being a
separate dwelling.
Class 3
A residential building, other than a Class 1 or 2 building, which is a
common place of long term or transient living for a number of
unrelated persons.
Example: boarding-house, hostel, backpacker’s accommodation or
residential part of a hotel, motel, school or detention centre.
Class 4
A dwelling in a building that is Class 5, 6, 7, 8 or 9 if it is the only
dwelling in the building.
Class 5
An office building used for professional or commercial purposes,
excluding buildings of Class 6, 7, 8 or 9.
Class 6
A shop or other building for the sale of goods by retail or the supply of
services direct to the public.
Example: café, restaurant, kiosk, hairdressers, showroom or service
station.
Class 7a
A building which is a car park.
Class 7b
A building which is for storage or display of goods or produce for sale
by wholesale.
Class 7
Class 8
A laboratory, or a building in which a handicraft or process for the
production, assembling, altering, repairing, packing, finishing, or
cleaning of goods or produce is carried on for trade, sale or gain.
A building of a public nature:
Class 9a
A health care building, including those parts of the building set aside
as a laboratory.
Class 9b
An assembly building, including a trade workshop, laboratory or the
like, in a primary or secondary school, but excluding any other parts of
the building that are of another class.
Class 9c
An aged care building.
Class 9
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