Environmental criteria for road traffic noise · • establish criteria that define acceptable...

Environmental criteria for road traffic noise

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Environmentalcriteria for road trafficnoise


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Published by:

Environment Protection Authority(until end October 1999)799 Pacific HighwayChatswoodPO Box 1135Chatswood 2057Phone: (02) 9795 5000 (switchboard)Phone: 131 555 (information & publications requests)Fax: (02) 9325 5678(from November 1999)59–61 Goulburn StreetPO Box A290Sydney South 1232Phone: (02) 9733 5000 (switchboard)Phone: 131 555 (information & publications requests)Fax: (02) 9733 5002

E-mail: [email protected]: www.epa.nsw.gov.au

For technical information about this report, please contact:

Noise Policy SectionEnvironmental Policy BranchEnvironment Protection AuthorityPhone: (02) 9795 5000 (until end October 1999)Phone: (02) 9733 5000 (from November 1999)

The EPA is pleased to allow this material to be reproduced in whole or in part, provided the meaning isunchanged and its source, publisher and authorship are acknowledged.

ISBN 0 7313 0203 6EPA 99/3

May 1999Printed on recycled paper


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Contents

1 Introduction 1

1.1 Traffic noise impacts in NSW 1

1.2 History of the criteria 1

1.3 Objectives of the criteria 1

1.4 Development of the criteria 3

2 The criteria 4

2.1 Assessing noise impacts 4

2.2 Road traffic noise criteria 4

Road traffic noise levels 4

Functional categories of roads 4

The criteria tables 5

Guide to terms used in the tables 11

Technical notes to the tables 11

Maximum noise levels 12

Where noise levels are already exceeded 13

Internal noise levels 14

3 Applying the criteria 15

3.1 Points to consider 15

3.2 Existing roads not subject to redevelopment 15

3.3 Individual road projects 16

3.4 New residential developments affected by road traffic noise 17

3.5 Land use developments that create traffic 18

3.6 General strategies 18

Appendix A: A history of road traffic noise criteria in NSW 20

Appendix B: Technical background to the road traffic noise criteria 22

Appendix C: Measuring traffic noise and preparing a noise impact statement 31

Bibliography 39

Glossary 41


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1 Introduction1.1 Traffic noise impacts in NSW

Our road system provides extensive benefits interms of the economic and social wellbeing of thecommunity. However, we need to reach a balancebetween providing efficient road transport infra-structure and controlling the adverse affects ofroad use.

The Government’s Action for Air Policy and theIntegrated Transport Plan for NSW set in placeoverall strategies for reducing the use of motorvehicles, in the interests of avoiding their environ-mental effects.

This policy also needs to be understood in thecontext of the Government’s metropolitan strategicobjectives. The Metropolitan Strategy provides thebroad framework for urban management in theGreater Metropolitan Region. A core goal of theMetropolitan Strategy is to establish a compact,efficient and accessible city. Encouraging higherdensity residential development and employmentclose to public transport and centres will be vital toachieving this goal. We must integrate land useand transport planning to increase accessibility andpublic transport use and reduce private vehicleuse; we need responsible noise management tomake this task easier.

Motor vehicle ownership in NSW has increasedsubstantially over the last 30 years, from 260vehicles per 1000 people in 1960 to 558 vehicles per1000 people in 1991. General levels of road trafficnoise throughout NSW have increased significantlythrough this period. There are currently fourmillion vehicles registered in NSW, and 86% of allfreight is moved by road.

A study conducted in 1986 (Hede et al. 1986)indicates the extent of road traffic noise impactsthroughout Australia. The study involved inter-views with a large random sample of the Austral-ian population. Twenty-one per cent of Australiansdescribed themselves as being personally affectedby noise pollution—more than for water, air orwaste pollution. Of the sources of environmentalnoise, the most important was road traffic noise,with 17% of the population describing it as thenoise they would most like to get rid of. Thesurvey found that 6% of Australians were highly

annoyed, and 21% moderately annoyed, by trafficnoise, with 13% claiming disturbance to listeningactivities, and 12% claiming disturbance to sleep.

This research shows that we need programs tocomplement strategies that are geared towardsreducing motor vehicle use with more effectiveways of managing existing levels of traffic noise,through influencing the nature of road design, roaduse and development adjacent to roads.

The Environmental Criteria for Road Traffic Noise area response to this need.

1.2 History of the criteria

The State Road Traffic Noise Task Force wasestablished in 1989 to develop strategies for thecontrol of traffic noise. The Task Force was com-posed of representatives from relevant Stateagencies, community groups, industry and theNRMA. The Task Force undertook a process ofextensive public consultation and released its FinalReport in November 1994.

The Final Report proposed under its general policyrecommendations that the EPA finalise ‘controlguidelines and environmental criteria for roadtraffic noise’ (p. 20).

1.3 Objectives of the criteria

The primary aims of this document are to:

• institute a more comprehensive and effectiveapproach to managing road traffic noise

• refocus the approach to mitigating roadtraffic noise from relatively late in the roaddevelopment process to a much earlier stage.This will allow land use planning andregulatory and policy decisions to beapplied to avoid noise wherever possible,which is a less costly and more effective wayto mitigate noise

• encourage the range of strategies that shouldbe applied to reducing traffic noise (forexample, traffic management, control of


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vehicle emissions, and driver education),and prevent over-reliance on engineeringnoise controls, such as noise barriers

• revise the noise level targets so that themethodology and levels provide criteria thatcan assess noise impacts and recognise thebenefits of all noise mitigation measures.

To control road traffic noise we need to:

• establish criteria that define acceptable noiselevels

• establish standard methods for assessing andmeasuring noise impacts

• identify all the strategies that can be adoptedto reduce traffic noise.

These are needed to provide a basis for:

• land use planners to consider how welljudicious location and design ofdevelopment can mitigate or avoidunacceptable noise impacts

• road designers and builders, regulators andthe community to consider the nature andextent of measures to avoid or reduce noisefrom new roads or from the redevelopmentof existing roads

• users of vehicles to consider how they canreduce noise.

The approach must reflect the fact that, in additionto road design and development controls, anumber of other strategies must be used to reducethe impact of traffic noise. They include:

• governing maximum noise levels fromindividual vehicles

• continuing encouragement of thecommunity to use public transport and toincrease the numbers of passengerstravelling in private vehicles.

This document provides a framework that guidesthe consideration and management of traffic noiseissues associated with new building developmentsnear existing or new roads, and new or upgradedroad developments adjacent to new or plannedbuilding developments. The framework mustallow the best mix of short-, medium- and long-term strategies to be selected to meet the appropri-ate noise level, given existing and emerging condi-tions. Noise impacts and mitigation measures mustbe considered early in the planning process. Whereplanning approaches are appropriate, they can bethe most effective and lowest cost means of miti-gating noise impacts.

The framework embodies a non-mandatory per-formance-based approach. The criteria are appliedas targets, but recognise that there will be situa-tions where planning strategies are not feasible.Solutions that can be reasonably applied in theshort term may not always meet the target. Forthese cases, a longer-term perspective needs to betaken to institute ongoing strategies that willminimise traffic noise impacts over time.

The approach embodied in this document is animportant departure from the traditional approach,which relies almost solely on addressing trafficnoise impacts in the road development process andthrough road engineering strategies such as noisebarriers. The ‘engineering’ approach is proving tobe increasingly costly and, equally importantly,does not always ensure that the community getsthe best protection from excessive noise. It ignoresthe considerable (and often less costly) gains thatcan be secured through land use planning, regula-tion of vehicles, driver education and carefulbuilding design.

In relation to land use planning, road planning androad design, the noise level criteria set out in thisdocument should be taken into account at an earlystage in planning a new development near aplanned or existing road, or in planning a newroad or new road use. If this is done, the effects ofroad traffic noise can be assessed and controlledthroughout the planning process. To the fullestextent possible, a new road should be aligned,

• developing programs to monitor and controlnoisy vehicles on the roads

• controlling noise from heavy vehicle exhaustand engine brakes

• implementing traffic management policies atlocal and regional levels (such as the use ofdedicated truck routes, enforcement of quietzones, and restricted access in residentialareas during sleeping hours)


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designed and constructed to meet the criteria. Ifthis is not practicable, other initiatives, such ascontrols on road-use behaviour—including speedor the use of exhaust brakes—and on land use andbuilding design, will need to be instituted toreduce impacts.

Similarly, it is expected that if planners of newdevelopments near roads consider these criteria,they will be able to develop formal planningmechanisms to avoid exposing future buildingoccupants to excessive noise.

The policy is not designed to be applied to existingroads for the purpose of retrofitting engineering-based noise mitigation works. Nevertheless, thenoise assessment methodology can be used to helpassess the impact of existing roads, bridges orfreeways on existing developments, and to developfeasible and reasonable approaches to reducingany excessive impacts over time.

A secondary aim of the policy is to institute anaccurate way of measuring the level of noiseimpact in existing and potential situations. Thiswill allow proper quantification of the extent ofnoise impact, and will also help assess the relativeimpacts for particular sites.

This will be particularly valuable for cost–benefitassessments of the options for mitigating noisefrom the redevelopment of existing road facilities,and also for selecting appropriate strategies forareas shown to have high levels of traffic noise.Strategies that may be adopted include enhancingroad design (such as improving pavement qualityand using noise barriers), enforcing noisy vehicleregulations, better traffic management, and (in thelonger term) improved vehicle noise controls andbetter land use planning.

Ultimately the intentions are:

• to allow the Department of Urban Affairsand Planning and local councils to developand set appropriate criteria, controls anduses for land affected by road traffic noise

• to help integrate land use planning and roadtransport planning

• to help road builders and managers to select

feasible and reasonable noise mitigationmeasures where these prove to be necessary

• to discourage road users from owning andoperating noisy vehicles.

1.4 Development of the criteria

The criteria have been developed on the basis ofthe most recent Australian and overseas data andresearch on best practice approaches to noiseprediction and management.

The EPA has identified a number of areas in whichthe current approach to noise assessment andlevels is deficient, including:

• for developments other than freeways, nospecific account is taken of the potential ofnoise to cause sleep disturbance

• there are serious practical difficulties in theevaluation of the traffic noise level (TNL)index previously relied upon to guide newroad developments

• the TNL index is based on technicallyachievable levels for road design, with nosensitivity to the relative cost orenvironmental effectiveness of other noisemanagement strategies

• there are apparent deficiencies in using asingle value for LAeq and L10 descriptors forpredicting certain types of disturbance,particularly to sleep

• no criteria are provided for assessing andmanaging impacts on land use other thanresidential

• existing noise criteria for local roads havebeen developed over a period of time,resulting in a piecemeal approach that hasrelied on both LAeq and L10 descriptors andthat does not differentiate day/nightperiods.

These Environmental Criteria for Road Traffic Noiseare intended to address the above perceiveddeficiencies. (Details of the old EPA traffic noiseguidelines, research findings and overseas ap-proaches are set down in Appendixes A and B).


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2 The criteria

2.1 Assessing noise impacts

Noise measurement and assessment methods arean integral part of implementing any set of noisecriteria. Noise measurement procedures are de-scribed in Appendix C, together with a step-by-step methodology for assessing the noise impactfrom road traffic.

2.2 Road traffic noise criteria

Road traffic noise levels

A number of factors should be considered insetting road traffic noise levels:

• whether there is an existing road corridorand, if so, whether the road project isintended to increase traffic-carrying capacitysubstantially, or whether the mix of trafficwould be substantially changed. Residentstend to be more sensitive to new noisesources than to existing noise sources of thesame noise level. The difference in sensitivityhas been identified in studies, and these arediscussed in Appendix B4. Furthermore,existing road corridors generally provideless scope for reducing noise levels

• whether or not substantial changes to thealignment of a road are proposed, orwhether the road is on a ‘new’ corridor. Incases where substantial road alignmentchanges are proposed or there is a new roadcorridor, there is maximum flexibility toselect best measures to meet noise levels atthe planning stage. This is a goodopportunity to achieve optimum noisemanagement through choosing a minimumimpact alignment, appropriate road design,and/or appropriate management ofdevelopment adjacent to an existing road

• whether the design/profile of a proposedroad is to be altered substantially. In thesecases, there is an opportunity to considernoise reduction options in the design phase(for example, putting a large proportion ofthe road in a tunnel, rather than at surfacelevel).

• whether the criteria are being applied inrelation to any redevelopment occurringadjacent to an established road. In thesecases, there is an opportunity to use theorientation and/or design of thedevelopment to control or reduce noiseimpact.

• whether the area affected is in an urban orrural environment where existing noiselevels will inevitably vary substantially, andwhere the response to additional noise willalso vary.

All these factors have been considered in thedevelopment of the noise level criteria.

Functional categories of roads

In Table 1, roads have been classified according tothe functional categories applied by the RTA. In theRTA Road Design Guide 1996 roads are differenti-ated by a range of factors, including traffic volume,heavy vehicle use, through or local traffic, vehiclespeeds and applicable traffic management options.The functional categories for roads consist of:

• arterial roads (including freeways), whichcarry predominantly through-traffic fromone region to another, forming principalavenues of communication for urban trafficmovements

• sub-arterial roads, which connect the arterialroads to areas of development and carrytraffic from one part of a region to another.They may also relieve traffic on arterialroads in some circumstances.

• collector roads, which connect the sub-arterial roads to the local road system indeveloped areas

• local roads, which are the subdivisionalroads within a particular developed area.These are used solely as local access roads.

It is noted that some industries (such as mines andextractive industries) are, by necessity, in locationsthat are often not served by arterial roads. Heavy


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vehicles must be able to get to their bases of opera-tion, and this may mean travelling on local roads.Good planning practice recognises that we mustacknowledge this type of road use and developways of managing any associated adverse impacts.To this end, the concept of ‘principal haulageroutes’ has been endorsed by the Department ofUrban Affairs and Planning’s North Coast Extrac-tive Industries Standing Committee. Ways ofidentifying ‘principal haulage routes’ and manag-ing associated adverse impacts have not yet beenfully defined. Where local authorities identify a‘principal haulage route’, the noise criteria for theroute should match those for collector roads,recognising the intent that they carry a differentlevel and mix of traffic to local roads.

The criteria tables

Table 1 sets out the criteria to be applied to particu-lar types of road and land uses, including residen-tial-, rural- and urban-zoned lands occupied bydwellings. In Table 1 arterial roads (includingfreeways) and sub-arterial roads are groupedtogether and are referred to as freeways/arterialroads.

Table 2 recognises that in some cases there will beextra noise sensitivities (for example, in hospitals

and schools) where more stringent standards areexpected. For the specific land uses of schools,hospitals and places of worship and recreation,criteria have been set with regard to the principlethat the characteristic activities for each of theseland uses should not be unduly disturbed.

The noise criteria in Table 2 are to be applied forassessing impact and determining mitigationmeasures in the following situations:

• a new road or road redevelopment

• a new noise-sensitive land use developmentaffected by road traffic noise

• a land use with the potential to createadditional traffic on local and/or collectorroads.

The values presented in the tables are intended topreserve amenity appropriate to the land use. Theconfidence for such an outcome occurring for thespecified noise levels is based on well-documentedsocial surveys defining a dose–response relation-ship between noise level and annoyance. Thesevalues are also supported by the comparison withoverseas criteria.


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Table 1. Road traffic noise criteria for proposed road or residential land usedevelopments

For an explanation of the terms used here, see the sections ‘Guide to terms used in the tables’ and ’Techni-cal notes to the tables’ immediately following the tables.

TYPE OF

DEVELOPMENT

CRITERIA

DAY

(7 am–10 pm)

dB(A)

NIGHT

(10 pm–7 am)

dB(A)

WHERE CRITERIA ARE ALREADYEXCEEDED

1. New freeway orarterial roadcorridor

LAeq(15hr)55 LAeq(9hr)50 The new road should be designed so as not toincrease existing noise levels by more than0.5 dB.

Where feasible and reasonable, noise levelsfrom existing roads should be reduced tomeet the noise criteria. In some instances thismay be achievable only through long-termstrategies such as improved planning, designand construction of adjoining land usedevelopments; reduced vehicle emissionlevels through new vehicle standards andregulation of in-service vehicles; greater use ofpublic transport; and alternative methods offreight haulage.

2. New residentialland usedevelopmentsaffected byfreeway/arterialtraffic noise

LAeq(15hr)55 LAeq(9hr)50 Where feasible and reasonable, existing noiselevels should be reduced to meet the noisecriteria via judicious design and constructionof the development.

Locations, internal layouts, building materialsand construction should be chosen so as tominimise noise impacts.

3. Redevelopmentof existingfreeway/arterialroad

LAeq(15hr)60 LAeq(9hr)55 In all cases, the redevelopment should bedesigned so as not to increase existing noiselevels by more than 2 dB.

Where feasible and reasonable, noise levelsfrom existing roads should be reduced tomeet the noise criteria. In many instances thismay be achievable only through long-termstrategies such as improved planning, designand construction of adjoining land usedevelopments; reduced vehicle emissionlevels through new vehicle standards andregulation of in-service vehicles; greater use ofpublic transport; and alternative methods offreight haulage.


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TYPE OF

DEVELOPMENT

CRITERIA

DAY

(7 am–

10 pm)

dB(A)

NIGHT

(10 pm–

7 am)

dB(A)


4. New collectorroad corridor

LAeq(1hr)60 LAeq(1hr)55 The new road should be designed so as not toincrease existing noise levels by more than 0.5 dB.

Where feasible and reasonable, noise levels fromexisting roads should be reduced to meet thenoise criteria. In some instances this may only beachievable through long-term strategies, such asimproved planning, design and construction ofadjoining land use developments; reduced vehicleemission levels through new vehicle standardsand regulation of in-service vehicles; greater useof public transport; and alternative methods offreight haulage.

5. New residentialdevelopmentsaffected by collectortraffic noise

LAeq(1hr)60 LAeq(1hr)55 Where feasible and reasonable, existing noiselevels should be reduced to meet the noise criteriavia judicious design and construction of thedevelopment.

Locations, internal layouts, building materials andconstruction should be chosen so as to minimisenoise impacts.

6. Redevelopmentof existing collectorroad

LAeq(1hr)60 LAeq(1hr)55 In all cases, the redevelopment should bedesigned so as not to increase existing noise levelsby more than 2 dB.

Where feasible and reasonable, noise levels fromexisting roads should be reduced to meet thenoise criteria. In many instances this may beachievable only through long-term strategies,such as improved planning, design andconstruction of adjoining land use developments;reduced vehicle emission levels through newvehicle standards and regulation of in-servicevehicles; greater use of public transport; andalternative methods of freight haulage.

7. Land usedevelopments withpotential to createadditional traffic onexistingfreeways/arterials

Leq(15hr)60 Leq(9hr)55 Where feasible, existing noise levels should bemitigated to meet the noise criteria. Examples ofapplicable strategies include appropriate locationof private access roads; regulating times of use;using clustering; using ‘quiet’ vehicles; and usingbarriers and acoustic treatments.

In all cases, traffic arising from the developmentshould not lead to an increase in existing noiselevels of more than 2 dB.


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CRITERIATYPE OF

DEVELOPMENT

DAY

(7 am–10 pm)dB(A)

NIGHT

(10 pm–7 am)dB(A)


8. Land usedevelopmentswith potential tocreate additionaltraffic on collectorroad

LAeq(1hr)60 LAeq(1hr)55 Where feasible and reasonable, existing noiselevels should be mitigated to meet the noisecriteria. Examples of applicable strategies includeappropriate location of private access roads;regulating times of use; using clustering; using‘quiet’ vehicles; and using barriers and acoustictreatments.

In all cases, traffic arising from the developmentshould not lead to an increase in existing noiselevels of more than 2 dB.

9. New local roadcorridor in ametropolitan area

LAeq(1hr)55 LAeq(1hr)50 The new road should be designed so as not toincrease existing noise levels by more than 0.5dB.

Where feasible and reasonable, noise levels fromexisting roads should be reduced to meet thenoise criteria. In many instances this may beachievable only through medium-term and long-term strategies, such as regulation of exhaustnoise from in-service vehicles; limitations onexhaust brake use; restricted access for sensitiveareas or during sensitive times to low-noisevehicles; improved planning, design andconstruction of adjoining land use developments;reduced vehicle emission levels through newvehicle standards; and alternative methods offreight haulage.

10. New localroad corridor in arural area

LAeq(1hr)50 LAeq(1hr)45

11. Newresidentialdevelopmentsaffected by trafficnoise from localroads

LAeq(1hr)55 LAeq(1hr)50 Where feasible and reasonable, existing noiselevels should be mitigated to meet the noisecriteria for occupants by judicious design andconstruction of the development.

Relevant strategies will include optimum locationand orientation of buildings on the site; planninginternal layouts carefully; choosing the mostappropriate building materials; and using goodconstruction techniques.


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CRITERIATYPE OF

DEVELOPMENT

DAY

(7 am–10 pm)dB(A)

NIGHT

(10 pm–7 am)dB(A)


12. Redevelopmentof existing localroads

LAeq(1hr)55 LAeq(1hr)50 In all cases, the redevelopment should bedesigned so as not to increase existing noiselevels by more than 2 dB.

Where feasible and reasonable, noise levelsfrom existing roads should be reduced tomeet the noise criteria. In many instancesthis may be achievable only throughmedium-term and long-term strategies, suchas regulation of exhaust noise from in-service vehicles; limitations on exhaustbrake use; restricted access for sensitiveareas or during sensitive times to low-noisevehicles; improved planning, design andconstruction of adjoining land usedevelopments; reduced vehicle emissionlevels through new vehicle standards; andalternative methods of freight haulage.

13. Land usedevelopments withpotential to createadditional traffic onlocal roads

LAeq(1hr)55 LAeq(1hr)50 Where feasible and reasonable, existingnoise levels should be mitigated to meet thenoise criteria. Examples of applicablestrategies include appropriate location ofprivate access roads; regulating times of use;using clustering; using ‘quiet’ vehicles; andusing barriers and acoustic treatments.

In all cases, traffic arising from thedevelopment should not lead to an increasein existing noise levels of more than 2 dB.


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Table 2. Road traffic noise criteria for sensitive land uses

For an explanation of terms used here see the sections ‘Guide to terms used in the tables’ and ‘Technicalnotes to the tables’ immediately following the tables.

CRITERIA SENSITIVELAND USE

DAY7 am–10 pm

dB(A)

NIGHT 10 pm–7 am

dB(A)

NOISE MITIGATION MEASURES

1. Proposedschoolclassrooms(For existingschools seeTechnical Notex)

L Aeq(1h) 40(internal)

-

2. Hospitalwards



3. Places ofworship



4. Activerecreation (forexample, golfcourses)

Collector andlocal roads:L Aeq(1h) 60

Freeway/arterial roads:L Aeq(15h) 60

-

5. Passiverecreation andschoolplaygrounds

Collector andlocal roads:L Aeq(1h) 55

Freeway/arterial roads:L Aeq(15h) 55

-

To achieve internal noise criteria in theshort term, the most practicablemitigation measures are often related tobuilding or façade treatments.

In the medium to longer term, strategiessuch as regulation of exhaust noise fromin-service vehicles, limitations onexhaust brake use, and restricting accessfor sensitive areas or during sensitivetimes to low noise vehicles can beapplied to mitigate noise impacts acrossthe road system. Other measuresinclude improved planning, design andconstruction of sensitive land usedevelopments; reduced new vehicleemission standards; greater use ofpublic transport; and alternativemethods of freight haulage. Thesemedium- to long-term strategies applyequally to mitigating internal andexternal noise levels.

Where existing levels of traffic noiseexceed the criteria, all feasible andreasonable noise control measuresshould be evaluated and applied. Wherethis has been done and the internal orexternal criteria (as appropriate) cannotbe achieved, the proposed road or landuse development should be designed soas not to increase existing road trafficnoise levels by more than 0.5 dB(A) fornew roads and 2 dB(A) for redevelopedroads or land use development withpotential to create additional traffic.


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Guide to terms used in the tables

Freeway/arterial includes sub-arterial roads andrefers to roads handling through-traffic, withcharacteristically heavy and continuous trafficflows during peak periods. Through-traffic istraffic passing through a locality bound for anotherlocality.

New freeway/arterial refers to a freeway, arterialor sub-arterial road that is proposed on a ‘corridor’that has not previously been a freeway, arterial orsub-arterial road; or an existing freeway, arterial orsub-arterial that is being substantially realigned.

Redevelop existing freeway/arterial refers to anexisting freeway, arterial or sub-arterial corridorwhere it is proposed to increase traffic-carryingcapacity, change the traffic mix or change the roadalignment through design or engineering changes.Redevelopment does not cover minor road worksdesigned to improve safety, such as straighteningcurves, installing traffic control devices or makingminor road alignments.

Collector road refers to a road situated in a built-up area that collects local traffic leaving a localityand connects to a sub-arterial road.

Redevelop existing collector road refers tochanges to a collector road corridor where it isproposed to increase the traffic-carrying capacity,change the traffic mix or change the road align-ment through design or engineering changes.Redevelopment does not cover minor road worksdesigned to improve safety, such as straighteningcurves, installing traffic control devices or makingminor road alignments.

Local road—metropolitan refers to a road situatedin built-up areas and handling local traffic. Theseroads characteristically have intermittent trafficflows. Metropolitan refers to the built-up area of acity or town, and includes both the urban zone ofthe CBD and adjacent localities, and the suburbanzone situated between the urban and rural zones.

Local road—rural refers to a road situated in ruralareas and handling local traffic with characteristi-cally intermittent traffic flows.

Redevelop existing local road refers to changes toa local road corridor where it is proposed toincrease the traffic-carrying capacity, change thetraffic mix or change the road alignment through

design or engineering changes. Redevelopmentdoes not cover minor road works designed toimprove safety, such as straightening curves,installing traffic control devices or making minorroad alignments.

Land use development with potential to createadditional traffic on existing roads implies in-creases to the magnitude of the traffic flow and/orchanges to the traffic mix brought about by newland use developments or significant alterations toexisting land use developments, which may notinvolve any construction to the road. This categorydoes not cover minor changes that are not subjectto either development consent or amendment to anEPA licence.

New residential development affected by trafficnoise addresses the acceptable level of road trafficnoise impact for new residential developments.

Technical notes to the tables

Details of the approaches to take when measuringand predicting noise are set out in Appendix C, butit is worthwhile to note here the key points ininterpreting the specified noise levels from atechnical perspective.

i Specified noise values refer to noise fromtraffic on roads, road bridges and freeways,and do not include ambient noise from othersources. However, they rely on all trafficnoise at the receiver location—not only noisedue to the project under consideration.

ii LAeq(1hr) represents the highest tenth percen-tile hourly A-weighted Leq during the period7 am to 10 pm or the period 10 pm to 7 am(whichever is relevant). If this cannot bedefined accurately, use the highest hourly A-weighted Leq noise level. More informationon LAeq is in Appendix C.

—LAeq(15hr) represents the Leq noise level forthe period 7 am to 10 pm.

—LAeq(9hr) represents the Leq noise level forthe period 10 pm to 7 am.

—The ‘A’ weighted Leq noise leveldescriptor has been chosen for use withthe criteria, and is designed to measure alevel of annoyance reaction caused byroad traffic noise. As explained in Appen-dix B, social surveys have shown that for


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existing noise, a level of LAeq 55 dB(A)equates to about 10% of a populationexposed to this noise level being highlyannoyed.

—Freeways and arterial roads handle highvolumes of through-traffic over extendedperiods of time; hence the need for a noisedescriptor that measures noise exposurefor the full day and night periods. Localroads in metropolitan areas, by contrast,handle only intermittent local traffic andrequire a shorter measurement period.

iii In assessing noise levels at residences, thenoise level is to be measured at 1 m from thefacade that is the most exposed to trafficnoise, and at a height of 1.5 m from the floorlevel. The residential noise level criterionincludes an allowance for noise reflectedfrom the facade (‘facade correction’). Ifreflection during measurement is unlikely(as, for instance, when measuring on openland before a residence is built), add anappropriate correction—generally2.5 dB(A)—to the measured value.

iv Where internal noise levels are specified,they refer to the noise level at the centre ofthe habitable room that is most exposed tothe traffic noise.

v In the case of multi-level residential build-ings, the external point of reference formeasurement for the criteria is the two floorsof the building that are most exposed totraffic noise (generally the ground and firstfloors). On other floors, the guideline is thatthe internal noise level should not exceed avalue 10 dB below the relevant externalnoise level on the basis of openable windowsbeing opened sufficiently to provide ad-equate ventilation (Refer to Building Code ofAustralia for additional information.) Formost residences this equates to a minimumof 20% of the window area left open.

vi For all road developments, the criteriashould apply on the basis of the trafficvolumes projected for 10 years’ time. Thenoise criteria should also apply immediatelyafter the road opens. In the case of buildingsused for education or health care, noise levelcriteria for spaces other than classrooms andwards may be obtained by interpolationfrom the ‘maximum’ levels shown in Aus-

tralian Standard 2107 Acoustics—Recom-mended design sound levels and reverberationtimes for building interiors.

vii For commercial and industrial develop-ments, information on desirable noise levelsis contained in Australian Standard 2107Acoustics—Recommended design sound levelsand reverberation times for building interiors.

viii In Table 1, for categories 3, 6 and 12 (rede-velopment of existing roads) and 7, 8 and 13(land use developments with the potential tocreate additional traffic), where the existingroad traffic noise levels lie within 2 dB of thenoise criteria, the 2 dB allowance can beapplied where all feasible and reasonablemitigation measures have been used. Thesame approach applies to categories 1, 4, 9and 10 (new road corridors) in Table 1,where a 0.5 dB allowance is assigned.

ix If the existing noise level is below the criteriabut within 2 dB of the criteria, then the 2dBallowance may be applied to the existingnoise level.

x In cases where existing schools are affectedby noise from proposed roads, the daytimecriterion is L Aeq(1h) 45dB(A) (internal).

Maximum noise levels

Unlike LAeq levels and annoyance reactions, therelationship between maximum noise levels andsleep disturbance is not currently well defined.(See Appendix B.) In addition, the effects of sleepdisturbance on health are not clear. While researchindicates that noise at low levels can cause auto-nomic reactions (including changes ingastrointestinal activity and cardiovascular re-sponses), there is no clear indication of what, if any,impact these reactions may have on health.

Based on a review of the relevant research (seeAppendix B), the following conclusions have beendrawn.

• Sleep disturbance occurs through twomechanisms: changes in sleep state andawakenings.

• Awakenings are better correlated tosubjective assessments of sleep quality thanare changes in sleep state.


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• Factors (other than noise) that contributesignificantly to awakening reactions includesleep state and subject age.

• The maximum noise level, the extent thatnoise exceeds the ambient noise level, andthe number of noise events, all contribute tosleep disturbance.

There are some unresolved points regarding sleepdisturbance and maximum noise levels. Evenwhere noise is not a factor, awakenings may stilloccur. Typically this level of awakening is 1 to 1.5per night. Thus, some level of sleep disturbancethrough awakenings that are not related to noiseincidents is quite usual. Further, the number ofadditional awakenings that would have a signifi-cant effect on health and wellbeing is yet to bedemonstrated. Similarly, the extent to which sleepstate and other sleep disturbance indicators affecthealth is still to be determined.

Therefore, at the current level of understanding, itis not possible to establish absolute noise levelcriteria that would correlate to an acceptable levelof sleep disturbance.

This does not mean that we should avoid consider-ing maximum noise levels. It does mean that weshould start to consider these levels broadly, andthat we should start more rigorous assessment andresearch on the sleep disturbance effects of trafficnoise.

At our present level of understanding, it is impor-tant that all of the noise characteristics of roadtraffic noise known to affect sleep are assessed.

This means that we should assess the likely maxi-mum noise levels from road traffic, the extent towhich these maximum noise levels exceed theambient noise level, and the likely number of noiseevents from road traffic during the night.

Because the relationship between noise, sleepdisturbance and health is not fully understood atthis stage, is not possible to define fully how thedifferent noise characteristics of road traffic shouldbe measured to best estimate effects on sleep.

The intention is to refine the definition of theimportant noise characteristics of road traffic noiseas understanding improves.

Maximum noise levels during each hour of thenight-time period should be assessed and reportedto give an indication of the likelihood of awaken-ing reactions.

Where noise levels are already exceeded

The fourth column in the tables shows the pre-ferred approach where existing noise levels alreadyexceed the noise criteria.

In areas where the criteria are exceeded by highexisting levels of road traffic noise, the capacity toemploy noise reduction measures will depend oncurrent circumstances and on whether any changeto the road and/or adjoining development is alsoproposed. The most stringent criteria apply to thedevelopment category with the most noise reduc-tion options, and the least stringent criteria applywhere there is little potential for noise control. Thisis discussed more fully below.

As a general principle, where reduction of existingnoise levels is possible, a reduction in noise levelsin line with the noise criteria is desirable. The bestcombination of short-term and long-term measuresshould be applied. In some instances it is expectedthat reduction in traffic noise levels will be practi-cable only over time. Long-term measures, such asreducing vehicle noise emissions through newAustralian Design Rules (ADRs), consideringexisting noise levels in planning decisions, anddeveloping alternative methods of transport, areexamples of applicable long-term strategies.

New road development in greenfield sites is likelyto present a wide range of potential noise controlmeasures and would not be expected to add toexisting noise levels from road traffic noise bymore than 0.5 dB.

The redevelopment of existing corridors offers amore limited range of noise control measuresbecause of likely limitations to using corridor routeadjustment, proximity of residents to the road andlimited road re-design options. Constructionactivity may, however, provide some potential atleast to contain noise increases as a result of thedevelopment. Measures should be formulated witha view to achieving the noise criteria. However,where this is demonstrated not to be feasible, it isexpected that strategies be implemented to contain


14

any increases to 2 dB above the prevailing noiselevel before re-development begins.

Upgrading of roads not designed to increase roadtraffic inherently should not create significant noiseimpacts.

New industrial, commercial or residential develop-ments that generate additional traffic on existingroads are likely to provide limited potential fornoise control, because such developments are notusually linked to road improvements. The criteriarecognise the difficulties in these cases by specify-ing that any road traffic noise increase should belimited to 2 dB above existing levels before thedevelopment takes place, where it is shown thatmeeting the criteria is not feasible and reasonable.

Where there is new residential development thatcan be affected by noise from existing roads, it isexpected that developers will be able to use anumber of noise control options to mitigate trafficnoise. These options include designing develop-ments so that sensitive land uses are protected fromexcessive noise through the use of options such asoptimum location and orientation on the site, well-planned internal layouts, noise insulating buildingmaterials and construction methods that facilitatenoise control.

Similarly, these principles can be applied toschools, hospitals, places of worship and thelocation of recreational areas.

Opportunities are more limited for existing landuses affected by existing roads, but where opportu-nities such as building improvements arise, noisecontrol measures should be applied as far aspracticable.

In the longer term, for all development and exist-ing use categories, strategies should be developedfor overall reductions in road traffic noise using thecriteria as the target.

Internal noise levels

It is preferable for internal noise level criteria to beset by the relevant planning or building authority.The internal levels that are set may vary dependingon the type of development the planning authoritywants to encourage for an area. The Hornsby Shireand Sydney City councils have codes for internalnoise level criteria in place. Sleeping areas areusually the most sensitive to noise impact, so in theabsence of any local codes internal levels of35–40 dBA at night are recommended. As a guidefor other living areas, internal noise levels 10 dBbelow external levels are recommended on thebasis of openable windows being opened suffi-ciently to provide adequate ventilation (refer toBuilding Code of Australia for additional informa-tion). For most residences this equates to a mini-mum of 20% of the window area left open.


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3 Applying the criteria

3.1 Points to consider

It is clear that to apply the road traffic noise criteriasuccessfully we will need an integrated manage-ment approach, involving a number of strategiesadministered by a number of agencies, over boththe short and longer terms. Some measures shouldbe adopted across the board; others need to bepursued in the context of individual road projects.

The non-mandatory nature of the criteria implies aprocess that needs to be followed to derive achiev-able noise levels for specific projects. That processcommences with the criteria providing the targetlevel that should be sought to be met and thenincorporates considerations of cost, feasibility,equity and community preferences. Where it can bedemonstrated that the target is not practicable,feasible or reasonable to achieve within the projectplanning, design and implementation for justifablereasons, then the criteria should be approached asclosely as possible, with the aim of adoptingbroader supporting strategies for achieving thecriteria in the longer term.

In this context, feasibility relates to engineeringconsiderations and what can practically be built(for example, whether the type of building wouldallow acoustic treatment of the facade, or whethera particular road design is possible given theavailable road corridor site constraints).

Reasonableness relates to the application of judge-ment, taking into account the following factors:

• noise mitigation benefits—amount of noisereduction provided, number of peopleprotected

• cost of mitigation—total cost and costvariation with benefit provided

• community views—aesthetic impacts andcommunity wishes

• noise levels for affected land uses—existingand future levels, and changes in noiselevels

• benefits arising from the development.

Although the criteria are non-mandatory, theyprovide the basis for establishing appropriate noiselevels that can be incorporated into conditions indevelopment consents issued by consent authori-ties (such as local authorities and DUAP) and intolicences issued by the EPA. Where noise levelconditions are set, they would result from startingwith the noise criteria as the targets and thenapplying all feasible and reasonable measures.Noise levels higher than the criteria may need to beapplied as a condition of consent where it isdemonstrated that the criteria cannot be met byapplying all feasible and reasonable mitigationmeasures.

3.2 Existing roads not subject toredevelopment

For existing roads (where no redevelopment istaking place), the primary role of the policy is toprovide a basis for measuring and defining theextent of any existing traffic noise impacts.

The targets for existing roads not subject to rede-velopment are:

• for existing freeway/arterial:

LAeq(15hr) 60 dB(A) day

LAeq(9hr) 55 dB(A) night

• for existing collector roads:


LAeq(1hr) 55 dB(A) night

• for existing local roads:


LAeq(1hr) 50 dB(A) night.

Resources are generally limited for noise control onexisting roads, and strategies need to take intoaccount what is reasonable and feasible; in manycases noise levels will have increased incrementallyover long periods of time, allowing for a degree ofhabituation to noise.


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Retrofitting of engineering-type noise controls isgenerally not recommended as a suitable strategyfor addressing existing undesirable levels of roadtraffic noise impact where no upgrading or rede-velopment is occurring. The reasons for this in-clude:

• relatively large urban areas are alreadysubjected to undesirable levels of road trafficnoise, and the benefits from retrofitting noisecontrols are usually limited to relativelysmall areas. To be effective, any strategyneeds to be able to address the widespreadnature of the impacts

• there are often high costs and practicaldifficulties associated with retrofitting noisecontrols.

The retrofitting of engineering-type noise controlsto existing roads where no upgrading or redevelop-ment is occurring should be limited to situationswhere there are acute noise impacts that requireprompt attention.

The Noise Abatement Strategy that has beendeveloped and implemented by the RTA on apriority basis for State-owned roads is an appropri-ate response for addressing acute existing trafficnoise impacts. This strategy directs resources toreceivers experiencing the highest road traffic noiseimpacts.

The preferred approach to addressing existing (andpotential) traffic noise impacts are through State-wide or region-wide strategies, such as: progres-sive reduction of vehicle noise emission standards;in-service inspections to ensure vehicle mufflers arewell maintained; driver education; traffic manage-ment (including limited access area for heavyvehicles); regulation of exhaust brakes; the integra-tion of transportation and land use planning; andthe promotion of design and construction of newhousing alongside transport corridors to minimisenoise impacts. These strategies offer the mostpromise in addressing existing (and potential)noise impacts in an overall fashion, rather thanrelying on piecemeal approaches such as theerection of noise barriers.

appropriate criteria (see Table 1 and Table 2) andstrategies should be applied. For new roads there isan even greater opportunity to ensure that noisecriteria are met.

In arriving at the level of traffic noise that wouldoccur in relation to any given road project, a techni-cal and economic assessment would normally bedone to establish feasible and reasonable options fornoise mitigation. Such an assessment would includetraffic noise criteria as a primary consideration.Other relevant factors—such as aesthetics, cost-effectiveness, engineering feasibility, equity issuesand community preferences—would also be consid-ered in the assessment process.

Where noise barriers are identified as the primarymeans of noise mitigation, then aesthetic consid-erations will include the protection of views, thepresence of shadowing, and the design of the noisebarriers.

Developing the details of the process to be fol-lowed in assessing noise mitigation for roaddevelopments is the job of road managers, whohave both the responsibility for assessing theimpacts of road developments and the relevantexpertise in noise mitigation works. The assess-ment process for determining feasible and reason-able noise mitigation works for individual roadprojects needs to provide the community with atransparent decision-making process and to ad-dress what can be done in situations where thechosen noise mitigation works do not meet thenoise targets.

For some transport corridors, the criteria would bereadily met through judicious road corridor selec-tion and road design. For more difficult situations,existing uses in the transport corridor may preventthe selection of a corridor that avoids impacts, andthe use of more effective road design strategiesmay still mean that noise exceeds the criteria. Inparticular, there may be practical problems incor-porating appropriate engineering solutions inexisting road corridors. In these cases, the propo-nent would be expected to collaborate with landuse authorities, and to identify the additionalstrategies needed to achieve the noise level criteria.

Where the existing traffic noise already exceeds thecriteria, the marginal noise allowance of 0.5 dB(new road) or 2 dB (road redevelopment) shouldbe applied only after all feasible mitigation meas-

3.3 Individual road projects

Opportunities to improve road traffic noise levelsarise when an existing road is redeveloped, and the


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ures have been assessed and all reasonable mitiga-tion measures applied. Before applying the allow-ance, the following issues need to be considered:

• Identify how all feasible and reasonablemeasures have been considered in seeking toachieve the noise criteria.

• Identify how road traffic noise levels can bereduced over time, from a strategicperspective, by applying measures such aslower vehicle noise emission limits (ADRs),driver education (on issues such as exhaustbrake use) and traffic management (forexample, on defined truck routes).

• Where it is not possible to show thatsignificant noise reductions would resultfrom these strategic approaches for theproject or location being considered, thenfeasibility and reasonableness of engineeringoptions such as road surface treatments andother acoustic treatments needs to beassessed.

• Finally, where strategic and project-specificmitigation measures have been shown not tobe feasible and reasonable, then a 0.5 dB (fornew roads) or a 2 dB (for redeveloped roadsand land use developments with potential tocreate additional traffic) increase in existingnoise levels is allowed.

Information on maximum noise levels can be usedto assess the relative impacts on sleep of differentoptions for new roadway developments, and torank maximum noise level impacts on residencesso that noise control measures can be prioritised.

Note that the impact of noise on sleep relates tonoise levels experienced inside the home1 . On thisbasis, approaches used to control noise impacts onsleep can be different from those used to addressannoyance.

• enforcing in-service noise emission limits

• improved land use planning

• improved noise design requirements forbuildings near heavily trafficked roads

• management of traffic through heavy vehicleroutes, with limited access to residentialareas.

3.4 New residential developmentsaffected by road traffic noise

New residential areas provide greater opportuni-ties for noise mitigation than existing develop-ments, because strategies can be implemented atboth the planning stages of a development as wellas at the individual allotment stage. In planningand designing a development it is important thatnoise be considered and balanced against otherdesign considerations, such as solar access, privacyand security.

Noise mitigation measures for new residentialdevelopments would include:

1 Considering traffic noise impacts whenplanning the development of areas andincorporating suitable measures such as:

—spatial separation between noisy activitiesand noise-sensitive areas through locatingless noise-sensitive land uses (activerecreation areas or access ways) in highnoise areas

—taking advantage of any natural topo-graphic features that can be used to screennoise impacts when planning land use inan area

—laying out subdivisions in ways thatmaximise the area shielded from noise

—using intervening structures such as multi-level buildings to act as barriers. Buildingsused as barriers should incorporate noise-quietening principles into their buildingdesign to ensure appropriate internalconditions.

2 Appropriate building design on develop-ment around roads to minimise noise im-pacts, for example by:

—including acoustic design principles when

1Appendix B5 reviews the current level of knowledge andconcludes that maximum internal noise levels below 50–55dBA are unlikely to cause awakening reactions, and that one ortwo noise events per night with maximum internal noise levelsof 65–70 dBA are not likely to affect health and wellbeingsignificantly.

The most promising strategies for limiting maxi-mum noise levels are:• reducing noise at the source through stricter

noise emission requirements on new vehicles


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planning landscaping for a site by examin-ing the suitability of earth berms, walls orfences to act as barriers

—designing buildings to locate noise-insensitive areas such as the kitchen,storage areas and laundry towards thenoise source; minimising the numbers andsize of windows oriented towards thenoise source; replacing a conventional roofdesign with eaves by a flat roof withparapets; and using the building structureto shield outdoor areas

—using construction techniques that paygood attention to sealing air gaps arounddoors and windows exposed to noise;using solid core doors; and using thickerwindow glass or double glazing.

There are a number of documents that provideadvice on planning and building design options tomitigate road traffic noise, including:

• A Guide for Homeowners, Designers andBuilders—Reducing Traffic Noise, availablefrom the RTA, dated August 1991.

• Traffic Noise and Your Next Home—brochureavailable from the RTA

• AMCORD—A National Resource Document forResidential Development, published by theformer Commonwealth Department ofHousing and Regional Development

• Better Urban Living, ‘Acoustic Privacy’section, pages 33–4, published by DUAP andthe Government Architect

• NSW Model Code published by DUAP.

3.5 Land use developments thatcreate traffic

Land use developments may have the potential tocreate additional traffic and affect existing residen-tial or other noise-sensitive land uses.

The criteria contemplate accepting an increase inlevels of existing traffic noise only after all feasibleand reasonable mitigation measures have beenapplied. The intent is to limit any additional trafficnoise impacts as far as practicable. In practice, theapplication of the 2 dB(A) allowance would need to

take into account the prevailing circumstances. Forexample, a development will not be able to obtainmultiple use of the 2 dB(A) allowance simply bydividing a large development into small segments.However, where a single development covers alarge area and separate changes are expected toincrease traffic noise to two widely separated areasaround the site (so as not to have any cumulativenoise impact), then the 2 dB(A) allowance may beapplied for each area. This, of course, would needto be assessed on a case-by-case basis. Whereseveral separate developments are proposed in anarea, and each is expected to contribute to anoverall cumulative noise impact, then as far aspossible these developments should be consideredboth individually and as a group for the purposesof assessing impacts and deciding mitigationmeasures.

For developments that create additional traffic,there may be situations where it is reasonable andnecessary to vary the standard time periods ap-plied to the day and night periods. For example,there will be instances where the noise levels in anarea begin to rise earlier than 7 am (the standardtime delineating day and night) due to normalearly morning activity from the general commu-nity. For these situations it is reasonable to considervarying the standard day- and night-time periodsto better reflect the actual temporal changes innoise for that location. In these situations, appro-priate noise level targets for the ‘shoulder periods’may be negotiated with the determining or regula-tory authority on a case-by-case basis.

3.6 General strategies

These strategies cover the three approaches tonoise control; that is, control of the source, controlin transmission, and control at the receiver. Solu-tions to the traffic noise problem can rarely befound through any single strategy. Any real gainwill generally depend on a combination of strate-gies.

The strategies listed in Table 3 are considered to beareas of high priority.


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Table 3. General traffic noise management strategies and responsible organisations

GENERAL TRAFFIC NOISE MANAGEMENT

STRATEGIES

RESPONSIBLEORGANISATIONS

HEAVY VEHICLE NOISE CONTROL

This includes engine/exhaust brakes,development/implementation of new AustralianDesign Rules, identification and policing of heavyvehicle preferred routes, and in-serviceenforcement.

RTA, EPA, local councils

PLANNING, DEVELOPMENT CONTROL ANDTRANSPORTATION PLANNING

This includes: DUAP and local councils developingformal mechanisms for ensuring that newdevelopment and redevelopment activities takeinto account noise from existing and proposed roaddevelopments; the inclusion of traffic noiseamelioration provisions for residential areas inAMCORD—Australian Model Code for ResidentialDevelopment; and the development of a ModelDevelopment Control Code.

DUAP, local councils, RTA, EPA

NOISE ABATEMENT STRATEGY

A priority ranking scheme and a range ofmitigation measures have been developed andimplemented for noise abatement on existing State-owned roads.

RTA

COMMUNITY EDUCATION ON VEHICLE USEAND NOISE MITIGATION

Develop education campaigns targeted at:

• vehicle repairers and heavy vehicle users

• the housing development industry and localcouncils.

Ongoing encouragement for the community to usepublic transport and to increase the numbers ofpassengers travelling per vehicle.

RTA, EPA

DUAP, EPA, local councils

EPA, DUAP, RTA

IN-SERVICE ENFORCEMENT

Strategies include programs to monitor andregulate noisy vehicles on the roads through in-service enforcement, and regulating againstmodifications to motor vehicle noise controlequipment that increase noise emissions.

RTA, EPA, police

Note: Organisations holding prime responsibility for the strategies are shown in bold.


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A1 Early EPA traffic noise guidelines

The first formal expression of traffic noise policy bya regulatory authority in NSW was in the Environ-mental Noise Control Manual, published by the(then) State Pollution Control Commission (SPCC)in 1985. This recommended a traffic noise levelgoal of 60 dB(A), L10(18hr) for major arterial roads. Italso recommended levels of 58 dB(A) L10(18hr) fornon-arterial roads, and 55 dB(A) L eq for intermit-tently-used roads.

Some concern was expressed at that time thatachieving the 60 dB(A) goal for arterial roadswould involve significant and unjustifiable addi-tional costs for housing and road construction. As aresult of subsequent interdepartmental consulta-tion, it was concluded that a noise level of 63 dB(A)L10(18hr) should be adopted as a provisional workingobjective for arterial road design and residentialarea planning. This traffic noise level was adoptedas the objective for major roads, with lower noiselevels set for minor roads and rural areas (see TableA.1).

A2 Use of TNL noise descriptor fornew freeways

Another significant influence in the developmentof traffic noise policy within the SPCC was therealisation that night-time noise levels (and par-ticularly noise levels from heavy vehicles) weresignificant in determining the reaction of residentsto traffic noise. Evidence for this came both fromthe results of Australian and overseas research andfrom practical experience, notably following theopening of the F3 freeway. Noise from this sectionof road generated considerable public reaction, as aresult of which the previously-designed noisemitigation measures were significantly (andexpensively) upgraded by the Roads and TrafficAuthority. This experience was considered to besub-optimal from both the economic and environ-mental perspectives.

In preparing its submission to the Commission ofInquiry into the proposed F2 freeway in 1992, the

Appendix A: A history of road traffic noisecriteria in NSW

EPA suggested the use of a noise level goal for newfreeways and similar roads, determined as thelevel at which about 10% of the population wouldbe highly annoyed by traffic noise. (Researchliterature provided a basis for the choice of a 10%highly annoyed figure.) On the basis of a re-analysis of research performed by Hede, a noisedescriptor referred to as the TNL (traffic noiselevel) was proposed. This descriptor is given by

TNL = Leq(24hr) + 0.1 MNH

where Leq(24hr) represents the Leq noise level over a24-hour period and MNH represents the meannumber of heavy vehicles per hour between 10 pmand 7 am. Hede’s research suggested that a level ofTNL 55 corresponds approximately with 10% ofresidents being highly annoyed by traffic noise.

The EPA emphasised at the F2 Commission ofInquiry that it understood the practical problems ofconstructing a new freeway to meet TNL 55 at allresidences, but recommended that efforts be madeto approach that level, subject to cost and technicalrestraints. A TNL level of 55 was regarded as anenvironmental goal, with the RTA being the appro-priate body to propose and evaluate the bestpracticable means to meet or approach the environ-mental criteria for specific individual circum-stances.

With the incorporation of this measure, the EPA’spreviously recommended traffic noise criteriachanged to the criteria set out in Table A1.

In cases where the noise levels in Table A1 werealready exceeded, the guideline recommended thatnew developments should not increase existinglevels by more than 2 dB.


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Table A1 Old EPA road traffic noise guidelines

ROAD TYPE DESCRIPTOR ENVIRONMENTALGOAL*

Freeways, tollways, etc. TNL 55 dB(A)

Arterial—urban and rural L10(18hrs) 63 dB(A)

Non-arterial—urban andrural

L10(18hrs) 58 dB(A)

Intermittent or low trafficflow, suburban

Leq(1hr) 55 dB(A) (new)

60 dB(A) (existing)

Low traffic flow, rural Leq(1hr) 50 dB(A) (new)

55 dB(A) (existing)

* measured within 1 m of a residential facade or other noise-sensitive location


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B1 Overseas criteria

In considering appropriate guidelines for roadtraffic noise, it is important to look at the criteriaused in other countries, as a guide to the noiselevels considered appropriate in residential areas.Table B1 shows criteria currently in place in anumber of countries (Lambert & Vallet 1993). Mostcountries have a variety of criteria, depending onthe zoning of the area receiving noise. Table B1compares criteria in residential areas.

The noise descriptor used by most countries todefine noise criteria is Leq. Where L eq is not used,usually a descriptor such as L10 or L50 is used.Lambert and Vallet (1993) point out that thedescriptor Ldn, used in the USA, is insensitive tonight-time noise level variations, and state that forthis reason it is an inappropriate descriptor to usein setting a criterion. They also comment that Leq iseasy to calculate, but it is not liked by residents,who find it hard to understand. They state thatresidents prefer L10, as it is perceived as better attaking traffic noise peaks into account. For continu-ous traffic noise, Leq and L10 are strongly correlated,L 10 being approximately 3 dB higher than Leq.

Daytime noise criteria range from 55 to 75 dB(A)Leq, while night-time criteria range from 45 to65 dB(A) Leq. Many countries place a more strin-gent limit on the night-time L eq level from roadtraffic noise than on the daytime level. Leq ismeasured or calculated over a variety of periods,from 24 hours (NSW RTA daytime criterion) to asingle peak-hour value (USA), with some countries(including France, Britain and America) assumingthat a single criterion will assure that both daytimeand night-time noise levels will be satisfactory. Theperiod over which the night-time Leq is to becalculated also varies considerably from country tocountry, and sometimes between regions in onecountry. This may partly be explained by a differ-ence in normal sleeping hours from one country tothe next.

A planning level of 50 to 55 dB(A) Leq appears to bethe most widely used night-time criterion, with adaytime criterion, also measured in Leq, set 10 dB

Appendix B: Technical background to theroad traffic noise criteria

above this. In many countries, variations in thecriteria are used in order to allow higher noiselevels on existing roads or roads in industrial areas,and lower noise levels on rural roads or roads nearnoise-sensitive land uses such as hospitals.


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Table B1 Comparison of residential traffic noise criteria

COUNTRY DAYTIME

CRITERIA

NIGHT-TIMECRITERIA

COMMENTS

France 60–70 dB(A) Leq

(8 am–8 pm)Not normally set Daytime criterion considered

acceptable, unless

Leq(day)–Leq(night)<6 dB(A).

Germany 62–70 dB(A) Leq(15h); inpractice 55 dB(A) isused.

52–60 dB(A) Leq(9h); inpractice 45 dB(A) isused.

Federal law

Greece Interior levels of 30–35 dB(A) in new buildings(all noise sources)

Criteria on traffic noise are beingdeveloped. Leq traffic noisecriterion is likely to be used infuture.

TheNetherlands

60–75 dB(A) Leq(7am–7pm) 50–65 dB(A) Leq(11pm–7am) 60 criteria to choose from,depending on zoning and stageof construction of road andresidences

Italy 55 dB(A) Leq(15h) 45 dB(A) Leq(9h) National law

Japan 60 dB(A) L50 50 dB(A) L50

55dB(A) L50 earlyam/late pm

Criteria increase if more than oneroad is nearby. L50 and Leq arecorrelated.

Spain Proposed criteria of55–75 dB(A) Leq

Proposed criteria of45–65 dB(A) Leq

No fixed laws—awaiting an EECdirective.

Switzerland 60 dB(A) Leq(15h)

reference level50 dB(A) Leq(9h)

reference levelPlanning levels 5 dB below thesecriteria.

UK 68 dB(A) L10(18h) Not set Equivalent to a criterion of

65 dB(A) Leq.

Proposed future planningcriterion is 55 dB(A) Leq.

USA 55 dB(A) Leq(peak hour) is ‘interference level’;67 dB(A) Leq(peak hour) is ‘intervention level’.

Criterion of Ldn = 65 dB(A) is alsosometimes used.


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B2 Reaction to road traffic noise

Noise reaction is a term used to describe theemotional response that is evoked by a loud noise.For most people, this response can be described asannoyance, but for some people other responsesare evoked. For example, people may choosewords related to annoyance to describe theirreaction (such as ‘annoyed’, ‘irritated’, ‘bothered’),but some may choose words related to fear (‘nerv-ous’, ‘scared’, ‘edgy’) or anger (‘cranky’, ‘angry’).All these types of responses are included in theterm ‘noise reaction’.

The only way that has been found reliably to assessthe strength of an individual’s noise reaction isthrough a social survey. Typically, the purpose ofthe survey would initially be disguised, to allowrespondents to rate their reaction to traffic noise inthe context of other environmental or neighbour-hood issues. Later, respondents would be askedquestions relating specifically to reaction to trafficnoise. Noise social surveys consistently focus onresidents as being the group potentially mostaffected by environmental noise.

In surveys, it is consistently found that measurednoise exposure explains only a small proportion ofthe variation in individuals’ noise reaction. Typi-cally between 10% and 25% of the total variation innoise reaction is explained by variation in noiseexposure. The remaining variation appears to bedue to individual differences in sensitivity to noisein general, or to traffic noise in particular.

However, the average reaction of a group ofpeople, or the proportion of people showing a highlevel of reaction, can be predicted relatively accu-rately from the noise exposure. One useful measureof noise reaction for a group of people is theproportion of those people who are ‘highly an-noyed’ by the noise. This term may have a specificmeaning in the context of an individual survey, butin general it is used to describe people who wouldchoose the designation ’highly annoyed’ from a listof categories to describe their annoyance.

The proportion of residents found to be seriouslyand moderately affected by road traffic noise isshown in Figure B1, plotted against noise exposureas measured by the daytime Leq noise level. Data inthis figure are drawn from a number of interna-tional studies, including one conducted in Bris-bane, Sydney and Melbourne (Brown 1978).

From Figure B1, 55 dB(A) Leq corresponds toapproximately 10% of residents highly annoyed,and 60 dB(A) Leq corresponds to approximately 18% of residents highly annoyed.

Based on research findings, the practice has devel-oped that environmental objectives for transporta-tion-related noise sources be set approximately atthe point at which 10 % of residents are highlyannoyed by the noise. This is the case, for example,with aircraft noise, where the 20 Australian NoiseExposure Forecast (ANEF) noise contour (belowwhich the construction of new residences is consid-ered ‘acceptable’) represents approximately the

Figure B1 Percentage of people highly annoyed by road traffic noise


25

point at which 10 % of residents are highly an-noyed.

This would indicate that, for road traffic noise,such objectives should be set at approximately 55dB(A) Leq for daytime noise exposure. However,other factors also influence the choice of a criterion,including the practicality of achieving the criterionin high-noise areas and the additional impact ofthe introduction of a new noise source to a rela-tively quiet environment. The latter factor isdiscussed in Section B4.

B3 Sleep disturbance due to trafficnoise—results of recent research

In addition to causing annoyance, traffic noise canalso significantly disturb specific activities withinresidences. Among these are:

• conversation, either in person or on thetelephone

• watching and listening to television

• sleeping

• relaxing, listening to music, reading andother passive indoor activities.

In general, studies of reaction to environmentalnoise indicate that the activity that most peoplewould like to have free from noise disturbance iswatching television. However, if only those peoplewho are seriously affected by the noise are consid-ered, the most important disturbance for thesepeople is to sleeping.

Disturbance to sleep as a result of environmentalnoise is a particularly emotive issue, raising thepossibility of effects on health, and other effects ofwhich a resident may not be fully aware. For thisreason, most researchers have preferred experi-mental methodologies to study the degree of sleepdisturbance caused by noise, rather than socialsurveys. The sleep disturbance can be assessed bysubjectively-reported sleep quality, number ofawakenings during the night (either self-reportedor as assessed with an electroencephalograph) ornumber of changes in sleep state.

The present review of results from this researchincludes studies of single noise events other thanmotor vehicle passbys, such as individual train and

aircraft passbys. The effects of these various noiseson sleep are assumed to be similar, for the samenoise level, so that results from the various studiescan be compared.

A number of experimental studies have concludedthat the use of the Leq noise level alone does notprovide an adequate measure of the sleep distur-bance produced by noise, and that a better meas-ure would be one that also takes account of thelevel and number of individual noise events, ornoise ‘peaks’. For example, Brown and Rutherford(1991), in their assessment of several publishedstudies of the effects of noise on sleep, concludethat, for continuous traffic noise conditions, Leqappears to provide an appropriate measure ofsleep disturbance, but that in cases where trafficnoise is intermittent (which is often the case atnight) sleep disturbance is affected more by thenumber of individual noise events exceeding aparticular level. They point out that various studiesindicate that it is the emergence of a noise eventabove the background that tends to lead to sleepdisturbance, rather than the actual peak noise levelof the event.

Eberhardt (1988) and Eberhardt et al. (1987) statethat the results of their studies indicate that incases of intermittent traffic flow Leq is an inad-equate descriptor of sleep disturbance, and needsto be complemented with some measure of noisepeaks. Eberhardt states that the emergence of noiseevents from the background—rather than theabsolute noise level of such events—determinesthe frequency of sleep disturbance. Eberhardt alsostates that high continuous traffic noise levels havean undesirable effect on REM sleep.

Vallet et al. (1983) conclude that it is possible to useLeq as a single noise index to measure sleep distur-bance due to continuous traffic flow. Vallet statesthat both Leq and Lmax are important in assessingsleep disturbance, but that for continuous trafficflow these two levels are correlated; therefore Leqalone can be used as an index. On the other hand,for intermittent traffic flow where the emergence ofa noise event, the number of noise events and theintervals between them become important, the useof Leq is not considered adequate, although Valletdoes postulate an approach whereby the Leq levelsof individual noise events are used to characteriseintermittent traffic noise. It is difficult to see howthis could be done in practice for road traffic noise.


26

Vernet (1979) finds that sleep disturbance is relatedto both Leq and Lmax, as well as to signal emergence.However, because in his results the Lmax andemergence were strongly correlated, he commentsthat it is difficult to discriminate between theireffects. Vernet (1983) also finds that in quiet areas itis emergence that is most closely related to sleepdisturbance, but that in noisier areas it is the noiseduration and peak level that are the more domi-nant factors.

Griefahn and Muzet (1978) find that the greater thedifference between the peak level of noise and theambient noise (that is, the greater the emergence ofa noise event) the greater the level of sleep distur-bance. Griefahn (1992) also finds that people aregenerally more disturbed by intermittent than bycontinuous noises, and he suggests that this indi-cates that Leq alone is not generally suitable for theprediction of sleep disturbance.

Ohrstrom and Bjorkman (1988), and Ohrstrom andRylander (1982), state that intermittent noise wasfound to have a significantly more noticeable effecton sleep quality than continuous noise at the sameLeq level; they suggest that these results imply thatpeak noise levels should be taken into accountwhen setting criteria for nocturnal noise. In one setof studies, Ohrstrom concludes that the Leq noiselevel was totally unrelated to sleep disturbanceeffects.

Horonjeff et al. (1982) conclude that the maximumlevel, duration and signal-to-noise ratio of a noiseevent are all closely related to the probability ofawakening. They suggest that awakening may bemore closely related to signal detectability (emer-gence) than to absolute level.

Griefahn and Muzet (1978) note that although thenumber of awakenings increases with the numberof noise events, this relationship is not a linear one,with less awakenings per event occurring as thenumber of events increases. Similarly, Ohrstromand Rylander (1990) indicate that the number ofawakenings from 64 events per night was fourtimes the number from eight events, rather thaneight times as expected. However, Vernet (1979)concludes that the number of noise events isclosely related to the number of disturbances tosleep.

In summary, the current literature concerning sleepdisturbance due to noise indicates that the main

noise characteristics that influence sleep distur-bance are the number of noisy events heard dis-tinctly above the background level, and the peaklevel and emergence of these events. The Leq,which is the energy average level of the noisesignal, takes some account of the number and levelof the louder events in a signal, due to the highamount of energy such events carry. However, theconsensus is that Leq by itself is an inadequatepredictor of the potential of a noise signal todisturb sleep. For continuous traffic flow, Leqappears to be acceptably correlated with sleepdisturbance, since under these conditions there arefew emergent noise events above the main hum ofthe traffic. However, for intermittent traffic flow,which often occurs at night, some other measurethat takes into account the emergence, peak leveland number of noise events is required.

B4 Response to a change in noiselevel

The data presented above are based on the re-sponses of people living in residences that havebeen exposed to road traffic noise for some time.However, the level of reaction to a newly intro-duced noise may not be directly predictable fromthese results. In simple terms, while people mayexpress a certain level of acceptance of theirexisting noise environment, they may feel stronglyabout any increase in noise.

There is evidence to suggest that reaction to anewly introduced noise source is considerablyhigher than reaction to a source that has beenpresent for some time. One study (reported inSchultz 1979), conducted in Japan, compared thereaction to noise near a newly-opened Shinkansen(fast train) line with the reaction near a line thathad been open for eight years. For the same noiselevel, reaction was higher near the newly openedline. The difference in reported annoyance wasequivalent to a difference of approximately 8 dB innoise exposure (Leq). The difference in reportedawakenings from sleep was equivalent to a differ-ence of 7dB in maximum noise levels.

An Australian study (Brown 1987) consideredreaction to a sudden increase in road traffic noiselevels. It was found that while reported reaction totraffic noise was consistent with other studiesbefore the change in exposure, after the change itwas higher than would have been predicted from


27

studies performed under conditions of constantexposure. The difference was equivalent to adifference of between 3 and 15 dB in noise expo-sure, this variation reflecting the uncertainty inpredicting reaction for a given exposure understeady conditions.

In addition, one study (Geoplan Resource Planning1992) investigated reaction to traffic noise inresidents living near the newly opened F3 freeway.The level of reaction was compared with that ofresidents living near the Pacific Highway, beforethe opening of the freeway, who were exposed tosimilar noise levels. The reaction of residents nearthe F3 freeway was found to be higher than that ofresidents near the Pacific Highway for the samenoise level, the difference being equivalent to adifference of approximately 9 dB in noise level.

The results of these studies are consistent, andindicate that where noise exposure is suddenly andsubstantially increased, reaction is higher thanwould be predicted from studies of steady condi-tions. Converse findings have been reported for thecase of reaction to a sudden decrease in exposure,that is, the reaction to the altered situation is lowerthan would have been predicted from the reactionto steady conditions.

On the other hand, very small increases (or de-creases) in noise exposure can be assumed to resultin only minor changes in noise reaction. Theminimum detectable change in a constant noiselevel is approximately 1 dB under ideal conditions,or 2 dB under field conditions. Given the fact that achange of this magnitude is likely not to be noticedby residents experiencing it, it can be assumed thatthe significant increase in noise reaction describedabove would not apply to changes in noise expo-sure of 2 dB or less.

B5 Potential noise level descriptorsfor assessing the impact of roadtraffic noise on sleep

The first step in determining a practical noise levelgoal for limiting sleep disturbance due to roadtraffic noise is to determine the units in which thegoal is to be expressed.

From the discussion in Appendix B3, the character-istics of a noise signal that are most stronglyrelated to sleep disturbance are:

• the peak level of noise events, described byLmax

• the emergence of noise events above thegeneral noise level, described by measuressuch as (Lmax– Leq) or (Lmax– L 90)

• the number of such noise events occurringduring the sleeping period.

Ideally, any night-time noise assessment methodol-ogy should take each of these factors into accountif it is to provide effective protection against sleepdisturbance. The use of single level indicators, suchas Leq, which is widely used to define night-timenoise criteria, does not take full account of all thesefactors.

In the light of studies such as Horonjeff et al.(1982), the SPCC incorporated a guideline in itsEnvironmental Noise Control Manual (1985) aimed atlimiting the level of sleep disturbance due toenvironmental noise—namely that the L1 level ofany noise should not exceed the ambient L 90 noiselevel by more than 15 dB. This criterion takes intoaccount the emergence of noise events, but doesnot directly limit the number of such events ortheir peak level, which are also found to affectsleep disturbance.

The use of an indicator such as L1 may appearfavourable, in that it represents the higher noiselevels experienced, and also takes some account ofthe number of events. However, L1 also dependson other characteristics of the noise (notably theduration of events) that are not strongly correlatedwith sleep disturbance. In addition, the value ofthis index is very difficult to predict using standardtraffic noise prediction methodologies.

Ultimately, a descriptor used to assess the impactof road traffic noise on sleep should be able topredict the level of sleep disturbance directly, as ispossible for annoyance using the daytime Leq level(Figure B1). This would necessarily involve arelatively complex methodology, taking intoaccount the distribution of numbers of noise eventsby noise level, as well as the emergence of noiseevents. Such a methodology has not yet beenadequately demonstrated or tested.

There is a large difference in the level of effects ofnoise on sleep between studies conducted in the


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laboratory and those conducted in the field. Labo-ratory studies usually show much greater levels ofsleep disturbance than for field studies at a givennoise level. The reason for such large variations hasnot been fully explained, but is probably due to thedifference in sleeping environments between thefield and laboratory studies.

Figure B2, extracted from Pearson et al. (1995),demonstrates the difference between laboratoryand field studies.

A number of researchers have produced resultsdesigned to allow an assessment of noisy events onsleep. The following examples provide a perspec-tive of the approaches and their results.

Figure B3, produced by Bullen et al. 1996, synthe-sises a number of studies that have been conductedinto sleep disturbance due to noise.

This graph demonstrates the problems in using thecurrent level of understanding of the effects of

Figure B2 Example of the different effects of noise on sleep in the laboratory and inthe field (Pearson et al. 1995)

Pearson, Barber, Tabachnick, Fidell, 1995

0

20

40

60

80

100

30 40 50 60 70 80 90 100 110 120

Sound Exposure Level (SEL)

Per

cent

Aro

used

or

Aw

aken

ed

Laboratory

Field

Figure B3 Awakenings due to noise (compiled from various studies)

0

2

4

6

8

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35 40 45 50 55 60 65 70 75 80

MAXIMUM INTERNAL NOISE LEVEL, dB(A)

AW

AK

EN

ING

S P

ER

100

EV

EN

TS

Eberhardt, '87(a)

Eberhardt, '87(b)

Eberhardt, '88

Ohrstrom,'82

Ohrstrom, '88(a)

Ohrstrom, '88(b)

Ohrstrom, '89

Ohrstrom, '90

Griefahn, '78

Vernet, '79

Thiessen, '78

Best-Fit Line

Bullen et al. (1996)

Pearson et al. (1995)


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noise on sleep to predict awakenings. For instance,the same probability of sleep disturbance is givenfor one event of 70 dB(A), ten events of 49 dB(A)and thirty events of 46 dB(A). However, it isunlikely that even a relatively high number ofnoise events at a low noise level would causeawakening reactions.

Figure B4 is adapted from Griefahn (1992). It showstwo lines: one derived from survey results, and asecond line adjusted to incorporate the increasedreaction to noise with age and adjusted to showawakening reaction in the most sensitive sleepstate.

Griefahn’s results show a very different level ofawakening reaction from that in Bullen’s figure B3.

Figure B5 is from Finegold et al. (1994), andpresents percentage awakenings compared withnoise events expressed in ASEL (A-weighted soundexposure level). The authors acknowledge theproblem with differences between laboratory andfield data and the need for further research. Theypresent their graph as a possible interim means ofevaluating awakening reactions from generaltransportation.

Griefahn 1992

0

10

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30

40

50

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70

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50 55 60 65 70 75 80 85 90 95 100 105 110 115 120

Maximum Noise Level, dB(A)

Pro

babi

lity

of A

wak

enin

g (%

)

Average level

Adjusted for age andsleep state

Figure B4 Probability of awakening related to age and sleep state (Griefahn 1992)

Again, the results presented in this graph bear littlerelationship to those in the previous two graphs. Toallow for a rough comparison, if it can be assumedthat the ASEL levels presented in figure B5 corre-spond to maximum noise levels of about 10 dBlower, then it is clear that Finegold’s results indi-cate a much higher level of reaction than thesynthesis presented by either Bullen or Griefahn.

Considering all of the foregoing information thefollowing conclusions can be drawn:

• Maximum internal noise levels below 50–55dBA are unlikely to cause awakeningreactions.

• One or two noise events per night, withmaximum internal noise levels of 65–70dBA, are not likely to affect health andwellbeing significantly.

More work is required to answer two essentialquestions:

• What is the cause–effect relationshipbetween noisy events and awakeningreactions in the home?

Greifahn (1992)


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• At what level do awakenings affect ourhealth and wellbeing?

Until more definitive information becomes avail-able, it will not be possible to develop noise levelcriteria for sleep disturbance that would have theequivalent level of confidence as those noisecriteria used for annoyance reactions.

Figure B5 Percentage awakenings from noise events expressed as ASEL (Finegold etal. 1994)

Finegold, Harris & von Gierke, 1994

0

10

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30

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20 30 40 50 60 70 80 90 100 110 120

Indoor A-weighted Sound Exposure Level, dB(A)

% A

wak

enin

gs

The EPA will continue to review research on sleepdisturbance as it becomes available. A more com-plete review exploring the two essential issuesraised above is planned.

Finegold et al. (1994)


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Appendix C: Measuring traffic noise andpreparing a noise impact statement

This appendix gives detailed guidance on measur-ing and predicting traffic noise levels and prepar-ing a noise impact statement. Three situations areconsidered—a new road, a new road use and anew development near an existing road. Details arealso given of the procedures required for monitor-ing existing noise levels, and of specific require-ments in noise calculation.

C1 Traffic noise assessment for a newroad

This section applies to assessments of traffic noisefrom new roads, road bridges and freeways wherea new road corridor is proposed, or to changes innoise levels due to substantial realignments ofexisting roads.

1 Determine land uses and area classifications,as set out in Tables 1 and 2 in section 2 of thisdocument, along the length of the new orupgraded road. (This is not necessary for afreeway or main arterial in Table 1, where asingle noise level criterion applies.)

2 Determine environmental noise level criteriafor each section of the road, using the levelsgiven in Tables 1 and 2 for each land use.

3 Conduct noise monitoring to determinewhether existing traffic noise levels alreadyexceed the noise level criteria for somelocations. Measurement procedures aredescribed in section C4. In cases where non-traffic noise constitutes an important part ofthe ambient noise in an area, monitoringneeds to be supplemented by calculation ofthe traffic noise component, carried out asdescribed in section C5.

Note that all noise descriptors that will beused in the assessment should be monitored.This may include LAeq(1hr), LAeq(15h), LAeq(9h)and maximum noise levels, depending onthe area classification and types of land useinvolved.

For the purpose of determining environmen-

these criteria may already be exceeded or arelikely to be exceeded; only limited monitor-ing would be required in areas with lowexisting traffic noise, where criteria areunlikely to be exceeded. However, if trafficnoise levels from existing roads are close tothe noise level goal, they could have aninfluence on the total traffic noise level afterroad construction. Note that in such casesany change in traffic volume on theseexisting roads, resulting from construction ofthe new road, would also need to be takeninto account.

4 Identify every potentially affected receiveralong the length of the proposed road, andassign a noise level criterion to each one.

5 Obtain accurate data on:

—the alignment of the proposed road,including gradient and heights of cuttingsand fill

—projected traffic speeds

—projected traffic volumes immediatelyafter opening and for a time ten yearsafter opening. (Break this down at leastinto the periods 7 am–10 pm and 10 pm–7 am, and specify the proportion of heavyvehicles for each period. Preferably, obtainprojected volumes for each hour and useaverage weekday volumes.)

6 Calculate noise levels, expressed in terms ofthe required descriptors, for each receiver, asdescribed in section C5, assuming no noiseamelioration measures are introduced.Calculated levels should include noise fromtraffic on the new road, and on any otherroads, which may influence the total trafficnoise level at the receiver.

7 Where the calculated noise level exceeds theenvironmental noise level criteria for anyreceiver, investigate the following ameliora-tive measures:

tal noise level criteria, the monitoringprogram needs only to define areas where

—use of alternative transport modes, orother methods of avoiding the new roadconstruction


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—alternative road alignments

—control of traffic (for example, limiting times of access or speed limitations)

—use of a quiet road surface

—use of noise barriers or bunds

—for non-residential buildings or residentialbuildings where the night-time criteria arethe major concern, treatment of the facadeto reduce internal noise levels.

8 If appropriate, re-calculate noise levels toinclude the effect of the proposed ameliora-tive measures. If noise levels still exceed theenvironmental level criteria, repeat theprocess.

9 In cases where (after the levels are calculatedas set out above and ameliorative measuresevaluated) it is considered impractical tomeet the required environmental noise levelcriteria, provide an assessment that addresses cost-versus-equity considerations,community preferences and actions thatcould achieve the criteria in the long term.

10 Include the following details in the acousticreport:

—diagrams showing the road alignment,land uses along the proposed road andnoise measurement locations. Theseshould be to a scale big enough to deline-ate individual residential blocks.

—details of the environmental noise levelcriteria at each potentially affected re-ceiver

—details of noise monitoring proceduresand/or calculations of existing noiselevels. This should include raw measure-ment data from each site, and assump-tions made in calculations, includingassumed traffic volumes and proportionsof heavy vehicles, as well as details of thecalculation procedure

—details of assumed data for the new road,including traffic volumes and percentageof heavy vehicles by time of day; anddetails of the calculation process, includ-ing assumed noise source heights forvehicles

—if required, a description of the ameliora-tive measures considered, reasons for

inclusion or exclusion, and procedures forcalculating noise levels, including amelio-rative measures

—a diagram showing noise level contours,or other methods of determining thecalculated noise level at each receiver,both with and without ameliorativemeasures

—if necessary, discussion of any potentialproblems associated with the proposedameliorative measures, such as overshad-owing effects.

—where the environmental noise levelcriteria set out in Tables 1 and 2 have notbeen met, a socioeconomic assessment ofthe proposal or the relevant part of theproposal, as discussed in point 9 undersection C1.

C2 Traffic noise assessment for a newroad use

This section applies to assessments of traffic noisefrom redeveloping an existing road and roadbridge, and for land use developments with thepotential to create additional traffic on existinglocal or collector roads.

1 Determine land uses and area classifications,as set out in Tables 1 and 2 in section 2 ofthis document, along the affected section ofthe road. (This is not necessary for a freewayor main arterial in Table 1, where a singlenoise level criterion applies.)

2 Determine environmental noise level criteriafor each section of the road, using the levelsgiven in Tables 1 and 2 for each land use.

3 Conduct noise monitoring to determinewhether existing traffic noise levels alreadyexceed the environmental noise level criteriaat some locations. Measurement proceduresare described in section C4. In cases wherenon-traffic noise constitutes an importantpart of the ambient noise in an area, moni-toring needs to be supplemented by calcula-tion of the traffic noise component, carriedout as described in section C5. Note that allthose noise descriptors that will be used inthe assessment should be monitored. Thismay include LAeq(1hr), LAeq(15h), LAeq(9h) and


33

maximum noise levels, depending on thearea classification and types of land useinvolved.

Monitoring would generally be done only atreceivers located near the existing road, todefine areas where these criteria mightalready be exceeded.

4 Identify every potentially affected receiveralong the affected section of the road, andassign an environmental noise level criterionto each one.

5 Obtain accurate data on the alignment of theproposed road redevelopment (includinggradient and heights of cuttings and fill),and on the projected volume and speed oftraffic to be introduced, broken down at leastinto the periods 7 am–10 pm and 10 pm–7am. Specify the proportion of heavy vehiclesfor each period. Preferably, obtain projectedvolumes for each hour, and use averageweekday volumes. Obtain similar data forexisting traffic on the road, since calculatedlevels represent the total traffic noise levelfrom the road.

6 Calculate noise levels (expressed in terms ofthe required descriptors) for each receiver,assuming no new noise amelioration meas-ures are introduced. Calculations may bedone as described in section C5, or may bebased on existing measured noise levels,with a correction for the variation in trafficconditions.

7 Where the calculated noise level exceeds theenvironmental noise level criteria for anyreceiver, investigate the following ameliora-tive measures:

—use of alternative transportation modes,alternative routes, or other methods ofavoiding the new road use

—control of traffic (for example, limitingtimes of access or speed limitations)

—resurfacing of the road using a quietsurface

—use of (additional) noise barriers or bunds

—for non-residential buildings or residentialbuildings where the night-time criteria arethe major concern, treatment of the facadeto reduce internal noise levels.

8 If appropriate, re-calculate noise levels toinclude the effect of the proposed ameliora-tive measures. If noise levels still exceed thenoise level criteria, repeat the process.

9 In cases where, after levels are calculated asset out above, it is considered impractical tomeet the required environmental noise levelcriteria, provide an assessment that ad-dresses cost-versus-equity considerations,community preferences and actions thatcould achieve the criteria in the long term.


—for projects with a significant potentialimpact, diagrams showing the roadalignment, land uses along the proposedroad, and noise measurement locations.These should be to a scale big enough todelineate individual residential blocks.

—details of the environmental noise levelcriteria at each potentially affected re-ceiver

—details of noise monitoring proceduresand/or calculations of existing noiselevels. Include raw measurement datafrom each site and the assumptions madein the calculations, including assumedtraffic volumes and proportion of heavyvehicles, as well as details of the calcula-tion procedure.

—details of assumed data for the new roaduse, including traffic volumes and per-centage heavy vehicles by time of day;details of the calculation process

—if required, a description of the ameliora-tive measures considered, reasons forinclusion or exclusion, and procedures forcalculating noise levels, including amelio-rative measures

—for projects with a significant potentialimpact, a diagram showing noise levelcontours, or other methods of determiningthe calculated noise level at each receiver,both with and without ameliorativemeasures

—if necessary, a discussion of any potentialproblems associated with the proposedameliorative measures, such as overshad-owing effects.


34

—where the environmental noise levelcriteria set out in Table 1 have not beenmet, a socioeconomic assessment of theproposal or the relevant part of the pro-posal, as discussed in point 9 of sectionC1.

C3 Traffic noise assessment for a newresidential or sensitive land usedevelopment near an existingfreeway/arterial or other roadwhere traffic noise is likely to be asignificant concern

This section applies to assessments of traffic noiseat proposed new residential or noise-sensitivedevelopments adjacent to existing freeways,tollways, heavy vehicle routes or major arterials; ornear other existing roads and bridges where it islikely that noise from traffic will be a significantconcern.

1 Determine the land use and area classifica-tion for the proposed development, as setout in Tables 1 and 2 in section 2 of thepolicy.

2 Determine the environmental noise levelcriteria, using the levels given in Tables 1and 2.

3 Conduct noise monitoring to determinewhether traffic noise levels exceed the noiselevel criteria at the relevant location. Meas-urement procedures are described in sectionC4. In cases where non-traffic noise consti-tutes an important part of the ambient noisein an area, monitoring needs to be supple-mented by calculation of the traffic noisecomponent, carried out as described insection C5.

Note that all noise descriptors that will beused in the assessment should be monitored.This may include L Aeq(1hr), L Aeq(15h), L Aeq(9h)and maximum noise levels, depending onthe area classification and the types of landuse involved.

For large potential developments, noisemeasurements may be supplemented bycalculations to determine noise levels atvarious locations.

4 Where the measured and/or calculatednoise level exceeds the noise level criteria forany receiver, the site would not normally beconsidered appropriate for the land use inquestion. However, it may be possible to usea number of ameliorative measures, includ-ing:

—redesigning or reorienting the building tominimise or eliminate the noise emissionto noise-sensitive areas within the build-ing and to external areas at the rear of thebuilding

—treatment of the building or its facade toreduce internal noise levels

—using noise barriers or bunds

—re-surfacing the existing road using a quietroad surface, at the developer’s expense.

5 If treatment of the façade is being consideredto reduce internal noise levels, it is necessaryto include requirements for ventilation. Forresidential and other proposed developmentwhere the noise level criteria are expressedin terms of external noise levels, it is desir-able that internal noise level criteria be 10 dBbelow the relevant external criteria cited inthis document.


—a diagram showing the proposed develop-ment in relation to the road alignment

—the environmental noise level criteria thatare determined

—details of noise monitoring proceduresand/or calculations of existing noiselevels. This should include raw measure-ment data from each site, and assump-tions made in calculations, includingassumed traffic volumes.

—the proportion of heavy vehicles, as wellas details of the calculation procedure

—a description of the ameliorative measuresconsidered, reasons for inclusion orexclusion, and the procedures for calculat-ing noise levels, including ameliorativemeasures


35

—if necessary, discussion of any potentialproblems associated with the proposedameliorative measures, such as overshad-owing effects.

C4 Noise monitoring procedures

This section describes the procedures used togather the noise information needed to apply thisdocument. This section is not intended to provide acomplete description of the procedures required toundertake a comprehensive noise-monitoringprogram. These procedures are documentedelsewhere, and are a part of general acousticpractice.

To measure the range of noise levels specified inthis document, any noise monitoring programmust be carefully designed. Select sites to cover therange of traffic noise conditions encountered in thearea of interest. Avoid locations with significantsources of noise other than road traffic. If this is notpossible, document these other sources and esti-mate their contribution to the measured noise level.Remember that in the application of this documentit is only levels of road traffic noise that are ofimportance.

L Aeq noise levels can be measured with noisemonitors or appropriate sound level metres, usingconventional techniques. Measuring systems maybe staffed or unstaffed, depending on the require-ments of the specific project.

• LAeq(15hr) is the L Aeq noise level for the period7 am to 10 pm. It is recommended that theLAeq be measured on a 15-minute basis.LAeq(15hr) = logarithmic average of all theindividual LAeq,15 min values from 7 am to10 pm, with the first reading taken at 7:15am and the last at 10:00 pm. Logarithmicaverage = 10 x log10((∑i=1 to n 10(LAeq,15 min,i/10))/n) where n = number of LAeq,15 min values ineach assessment period over themeasurement period.

• LAeq (9hr) is the L Aeq noise level for the period10 pm to 7 am. It is recommended that theLAeq be measured on a 15-minute basis.LAeq(9hr) = logarithmic average of all theindividual LAeq,15 min values from 10pm to7am, with the first reading taken at 10:15 pmand the last at 7:00 am. Logarithmic average= 10 x log10((∑i=1 to n 10(LAeq,15 min,i/10))/n),

where n = number of LAeq,15 min values in eachassessment period over the measurementperiod.

• LAeq(1hr) is the L Aeq noise level for a specificone-hour period. LAeq(1hr) represents thehighest tenth percentile hourly LAeq noiselevel (or, if this cannot be accurately defined,the LAeq noise level for the noisiest hour)during the period 7 am to 10 pm or theperiod 10 pm to 7 am, as relevant. It isrecommended that the LAeq be measured ona 15-minute basis. Logarithmic average =10 x log10 ((∑i=1 to n 10(LAeq,15 min,i/10))/n), wheren = number of LAeq,15 min values in eachassessment period over the measurementperiod.

The most appropriate currently available methodsof determining maximum noise levels as requiredfor this document are:

• the use of a chart recorder, or

• electronic storage of instantaneous soundpressure levels at intervals of about 1/4second.

In either case, ‘fast’ speed rectification should beused. Storage of longer-period noise levels, such as1–second Leq levels, may be appropriate, butshould be justified on the basis that shorter-termfluctuations in noise levels are unlikely in thecircumstances involved.

For unstaffed monitoring, the arrangement ofinstruments would normally involve a standardnoise logger with a signal output to the storagedevice. With a chart recorder, and possibly alsowith electronic storage, the data have to be re-trieved after each monitoring night.

Maximum noise levels during the night-timeperiod (10 pm–7 am) should be assessed to analysepossible affects on sleep. The assessment shouldencompass the likely maximum noise levels due toroad traffic, the extent to which these maximumnoise levels exceed ambient noise levels, and thenumber of noise events from road traffic during thenight on an hourly basis for a ‘typical’ night.

Noise levels that are attributable to sources otherthan road traffic, including sirens on emergencyvehicles, should be discarded.


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When describing the measurement and analysisprocedures used in any monitoring program, givedetails of the method used to determine maximumnoise levels.

C5 Noise calculation procedures

The calculation of traffic noise levels may be basedon one or more of a number of modelling proce-dures, each of which has its advantages anddisadvantages. The three models generally used inAustralia are:

• ‘Calculation of Road Traffic Noise’—theCORTN model. This has the advantage ofhaving been specifically validated underAustralian conditions, and specificcorrections can be included to account forthe results of this validation study. It is alsorelatively simple to use, and for this reasonmay be the most appropriate method forrelatively small projects. However, themethod provides only relatively simplisticcorrections for percentage of heavy vehiclesand distance from the roadway. In addition,results are in terms of L10(18hr) and requirecorrections to give predicted levels for othernoise descriptors. Source of model: UKDepartment of Transport or UK Departmentof Environment.

• ‘Federal Highway Administration Model—the FHWA model. This has the advantage ofallowing direct calculation of LAeq noiselevels, based on stated assumptionsregarding the noise emission levels ofvarious classes of vehicles. Where the noiseemission levels differ from those assumed,adjustment to the model is relatively easy.Furthermore, the calculation algorithms aregenerally considered to be mathematicallymore rigorous than those of the CORTNmethod, leading to greater accuracy and awider range of validity at low traffic flows.Source of model: US Federal HighwayAdministration/US Department ofTransport.

• Environment Noise Model—the ENMmodel. This model incorporates a moresophisticated ground effect correction, andmay be the most appropriate model forcalculating noise levels at large distances

from a road. However, the model isrelatively complex to set up and use. Sourceof model: RTA Technology Pty Ltd.

For more information on the models see the follow-ing references: Brown (1989), Hede (1995) and UKDoT (1988).

The use of one or more of the above models, or anyother procedure, should be justified according tothe circumstances of the particular project.

A point that should be taken into account in anytraffic noise calculation is the effective vehicleheight. This can be crucial in determining thepredicted attenuation from barriers. The effectiveheight of light vehicles is generally taken as0.5 metres, and this appears to give acceptableresults. However, for heavy vehicles there are oftentwo distinct sources, representing the engine andthe exhaust, with different noise emission levelsand different heights. The recommended practice isto model heavy vehicles as two sources, calculatingthe barrier attenuation for each and adding thefinal result. The procedure used in any specific caseshould be documented and justified in the report.

The prediction of maximum noise levels during thenight-time period involves consideration of thelikely sources of these noise maxima. They willgenerally be due to heavy vehicle movements, andin most cases the number of these movements willbe sufficiently low that noise events can be identi-fied with the passing of a single vehicle.

Because the maximum noise levels from individualheavy vehicles vary, the distribution of noise levelsfrom these vehicles may need to be taken intoaccount in order to determine the representativevalues for maximum noise levels; the extent towhich the maximum noise levels exceed theambient noise levels; and the number of noiseevents. The decision as to the level of detail to beadopted in calculations will depend on the sizeand potential impact of specific projects, and onthe level of detail needed for noise ameliorationdesign requirements.

Where there are very high numbers of heavyvehicle movements at night, it may become diffi-cult or impractical to identify noise level maximawith the passing of a single heavy vehicle. How-ever, in these cases, experience indicates that thedifference between maximum and LAeq noise levels


37

will be less than 15 dB. Under these circumstancesthe design of noise control measures will generallybe governed by the night-time LAeq criterion.

Of the models described above, only ENM candirectly predict maximum noise levels from anindividual source. However, the algorithm used inthe FHWA method can be adapted to do this andother methods may be available.

Figure C1 compares the noise levels emitted fromsome common sources.


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Figure C1. An illustrated comparison of common noise sources

Source: Road Traffic Noise Task Force Final Report

DECIBELS


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ReferencesBradely J. S. & Jonah B. A. 1977, A Field Study ofHuman Responses to Road Traffic Noise and to AircraftNoise. Report SV–77–2, Faculty of EngineeringScience, University of Western Ontario.

Brown, A. L. 1978, Traffic Noise Annoyance AlongUrban Roadways, A.R.R.B. Report AIR 206–6. Reporton Survey in Brisbane, Sydney and Melbourne,Australian Road Research Board.

Brown, A. L. 1987, ‘Responses to an Increase inRoad Traffic Noise’, Jnl Sound & Vibration (JS&V)117(1), 69–79.

Brown A L, 1989, ‘Some Simple Transformationsfor Road Traffic Noise Scales’, Australian RoadResearch, Melbourne, pp. 309–12 vol. 19, no.4,December.

Brown, A. L. & Rutherford, S. 1991, Criteria for theControl of Night-time Road Traffic Noise: Directionsfrom the Current Research Literature, Report for theNSW RTA, School of Environmental Studies,Griffith University.

Brown, A. L 1994, Road Traffic Noise—the Extent ofthe National Problem. Proc. 1994 Conference of theAustralian Acoustical Society, 150–5.

Bullen, R., Hede, A. & Williams, T. 1996, ‘SleepDisturbance Due to Environmental Noise: AProposed Assessment Index’, Acoustic Australia,vol. 24 no. 3.

Eberhardt, J. L., Strale, L. & Berlin, M. 1987, ‘TheInfluence of Continuous and Intermittent TrafficNoise on Sleep’, JS&V vol. 116(3).

Eberhardt, J. L. 1988, ‘The Influence of Road TrafficNoise on Sleep’, JS&V vol. 127(3).

Finegold L. S., Harris C. S. & von Gierke H. E. 1994,‘Community Annoyance and Sleep Disturbance:Updated Criteria for Assessing the Impacts ofGeneral Transportation Noise on People’, NoiseControl Engineering 42(1).

Geoplan Resource Planning Pty Ltd 1992, Berowra–Wahroonga Freeway: Noise Opinion Surveys. Reportprepared for Roads and Traffic Authority, RTA,Sydney.

Griefahn, B. & Muzet, A. 1978, ‘Noise InducedSleep Disturbances and their Effects on Health’JS&V vol. 59(1).

Griefahn, B. 1992, ‘Noise Control During theNight’, Acoustics Australia, vol. 20 no. 2.

Hede, A., Meagher, D. & Watkins, D. 1986, Commu-nity Response to Noise in Australia: Results of the 1986National Noise Survey, Proceeedings of the Commu-nity Noise Conference Toowoomba, 1–3 October.

Hede, A. J. 1995, Traffic Noise Level—An ImprovedIndex for Estimating Community Exposure. Proc. 1985Conference of the Australian Acoustical Society,13–18.

Hall, F. L., Birnie, S. E., Taylor, S. E. & Palmer, J. E.1981, ‘Direct Comparison of Community Responseto Road Traffic Noise’, Jnl Acoust. Soc. Am. 70,1690–8.

Horonjeff R., Fidell, S., Teffeteller, S. & Green, D.1982, ‘Behavioural Awakenings as Functions ofDuration and Delectability of Noise Intrusions inthe Home’, JS&V vol. 84(3).

Lambert, J. & Vallet, M. 1993, ‘Recherche d’unIndice Acoustique de Gene Nocturne Liee au TraficRoutier, INRETS, France.

Nemecek, J., Wehrli, B. & Turrian, V. 1981, ‘Effectsof the Noise of Street Traffic in Switzerland: AReview of Four Surveys’, JS&V vol. 78, 231.

Ohrstrom, E. & Bjorkman, M. 1988, ‘Effects ofNoise Disturbed Sleep—A Laboratory Study onHabituation and Subjective Noise Sensitivity’,JS&V vol. 122(2).

Ohrstrom, E. & Rylander, R. 1982, ‘Sleep Distur-bance Effects of Traffic Noise—A Laboratory Studyon After Effects’, JS&V vol. 84(1).

Ohrstrom, E. & Rylander, R. 1990, ‘Sleep Distur-bance by Road Traffic Noise—A Laboratory Studyon Number of Noise Events, JS&V vol. 143(1).

Pearson, K. S., Barber, D. S., Tabachnick, B. G. &Fiddell, S. 1995, ‘Predicting Noise-induced SleepDisturbance, Jnl Acoust Soc Am 97(1).


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Roads and Traffic Authority, 1996, ‘Road DesignGuide’, NSW RTA.

Saunders R. E., Samuels S. E., Leach R. & Hall A.,1983, An Evaluation of the UK DoE Traffic NoisePrediction Method, ARRB Research Report, Mel-bourne.

Schultz, T. J. 1978, ‘Synthesis of Social Survey onNoise Annoyance’, Jnl Acoust Soc Am 64, 377–405.

Schultz, T. J. 1979, Noise Rating Criteria for ElevatedRapid Transit System, U.S. Department of TransportReport No. UMTA–MA–06–0099–79–3.

UK DoT (Welsh Office), 1988, Calculation of RoadTraffic Noise (CRTN), HMSO, London.

Vallet, M., Gagneux, J., Blanchet, V., Favre, B., &Labiale, G. 1983, ‘Long Term Sleep DisturbanceDue to Traffic Noise’, JS&V vol. 90(2).

Vernet, M. 1979, ‘Effect of Train Noise on Sleep forPeople Living in Houses Bordering the RailwayLine’ JS&V vol. 66(3).

Vernet, M. 1983, ‘Comparison Between Train Noiseand Road Noise Annoyance During Sleep’ JS&Vvol. 87(2).


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Glossary

ADR

ambient noise

ANEF

annoyance

A–weighting

barrier—noise

buffer

dB

dB(A)

Australian Design Rules

The general environmentalnoise at any specific location,being a composite of soundsfrom many sources, both nearand far.

The most common type ofreaction felt by residentstowards traffic noise. Thedegree of annoyance felt by anindividual may be assessedusing social survey techniques.

An adjustment made to soundlevel measurement, by meansof an electronic filter, to ap-proximate the response ofthe human ear.

Any natural or artificial physi-cal barrier to the propagationof noise (from a roadway), butgenerally referring to acousti-cally reflective or absorbentfences, walls or mounds (orcombinations thereof) con-structed beside a roadway.

An area of land between aroadway and a noise-sensitiveland use, used as open space orfor some other noise-tolerantland use.

Decibel, which is 10 times thelogarithm (base 10) of the ratioof a given sound pressure to areference pressure; used as aunit of sound.

Unit used to measure ‘A–weighted’ sound pressurelevels.

Australian Noise ExposureForecast

EPA

grade (road)

greenfield sites

heavy vehicle

highly annoyed

L1

L10

L10 (1hr)

L 10(18hr)

Environment ProtectionAuthority

Sites that do not accommodateexisting roads

A truck, transport or othervehicle with a gross vehicleweight above a specified level(for example: over 8 tonnes)

An individual is generallyreferred to as being ‘highlyannoyed’ by a specific type ofnoise if in a social survey theychoose ‘highly annoyed’ from alist of possible descriptions oftheir reaction (such as ‘highly,moderately, slightly, or not atall annoyed’), or if they ratetheir annoyance as at leasteight on a ten point scale.

The sound pressure level thatis exceeded for 1% of the timefor which the given sound ismeasured.

The sound pressure level thatis exceeded for 10% of the timefor which the given sound ismeasured.

The L 10 level measured over a1-hour period.

The arithmetic average of theL 10(1hr) levels for the 18-hourperiod between 0600 and 2400hours on a normal workingday. It is a common traffic noisedescriptor.

Department of Urban Affairsand Planning

DUAP

The line or slope of a road—that is, the angle of a road tothe horizontal plane, expressedas a percentage.


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LAeq

LAeq(15hr)

LAeq (9hr)

LAeq(1hr)

maximum noiselevel

mound

noise impactstatement

noise level(goal)

Equivalent sound pressurelevel—the steady sound levelthat, over a specified period oftime, would produce the sameenergy equivalence as thefluctuating sound levelactually occurring.

The L Aeq noise level for theperiod 7 am to 10 pm

The L Aeq noise level for theperiod 10 pm to 7 am

The L Aeq noise level for a one-hour period. In the context ofthis policy it represents thehighest tenth percentile hourlyA-weighted Leq during theperiod 7 am to 10 pm, or 10 pmto 7 am (whichever is relevant).If this cannot be defined accu-rately, use the highest A-weighted Leq noise level.

Maximum level value of soundpressure, measured at a givenlocation over a specified timeinterval.

A type of noise control barrierconsisting of an artificialearthen embankment or knollconstructed between a road-way and a noise receptor area.

A document setting out theexisting noise impacts at aspecific location, and, gener-ally, the expected change innoise impacts that wouldresult from a proposeddevelopment; includes strate-gies and controls to mitigatenoise impacts.

A noise level that should beadopted for planning purposesas the highest acceptable noiselevel for the specific area, landuse and time of day.

The response evoked in alistener by a noise. For trafficnoise, this can usually be de-scribed as ‘annoyance’, but mayalso include fear, anger andother reactions.

noise reaction

noise-tolerant(land use)

RTA

sound pressurelevel

set-back

threshold

traffic noise

WHO

Types of land use that are notgenerally regarded as beingsensitive to relatively high noiselevels—in the range 60–80dB(A)—for example, openspace, pasture/grazing, indus-trial, port facilities).

The level of noise, usuallyexpressed in dB(A), as meas-ured by a standard sound levelmeter with a pressure micro-phone. The sound pressure levelin dB(A) gives a close indicationof the subjective loudness of thenoise.

The distance between thebuilding alignment or face andthe corresponding land bounda-ries of a property, minima forwhich are controlled throughplanning regulation

The lowest sound pressure levelthat produces a detectableresponse (in an instrument/person).

The total noise resulting fromroad traffic, including both lightand heavy vehicles, steady andintermittent traffic flow andspecific events such as the useof engine brakes.

World Health Organisation

Roads and Traffic Authority

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