Methods of Assessment of Aircraft Noise - Acoustics

London South Bank University

Department of Engineering Systems

MSc in Environmental and Architectural Acoustics

METHODS OF ASSESSMENT OF AIRCRAFT NOISE

N J S Burton

2004

A project in partial fulfilment of the requirements of the degree of Master of

Science in Environmental and Architectural Acoustics

ABSTRACT

This project examines various methods used for the assessment of aircraft

noise adopted both historically and internationally. The project is divided into

two parts.

The first part of the project examines a number of the most common methods

for the assessment of aircraft noise adopted in the past and at present as

well as identifying new methods proposed for future use. The philosophy

behind these methods is considered and their respective advantages and

disadvantages in gauging the problems caused by aircraft noise examined.

The second part of the project involves the computer modelling of aircraft

noise resulting from operations at a theoretical airport using a number of the

different noise descriptors examined in the first part of the project. The

results of the noise modelling, and the planning criteria adopted in their

respective country or region of origin, are been compared to identify which

methods produce the worst case and best case scenarios.

The results of the modelling exercise indicate that the Australian system

operates the most stringent controls with regards to aircraft noise and

residential planning whilst the systems adopted in the USA are the least

strict.

ACKNOWLEDGEMENTS

I would like to acknowledge and thank the following for their kind assistance

and support during the preparation of this thesis:

• Professor Bridget Shield of London South Bank University for her

assistance in refining the scope of this project and her guidance on

sources of previous research material.

• Dr Stephen Dance of London South Bank University for his

encouragement, supervision and for reading through the numerous

drafts.

• Bickerdike Allen Partners for providing the tools and the time for me to

complete this project and, in particular, Mr Jeff Charles for reading

several drafts and imparting his knowledge and offering his

constructive criticism.

• Mr Tom Lowrey of Transport Canada for providing information on the

methods of assessment of aircraft noise in Canada.

• Mr Jonathan Firth, Mr Nick Fisher and Ms Donna Perera of the

Department of Transport and Regional Services in Australia for

providing information on the methods of assessment of aircraft noise

in Australia.

• My parents, Mr John and Mrs Evelyn Burton, and my fiancée,

Miss Lesley Kemp, for their unconditional love, unfailing support and

for attempting to understand what this is all about.

ABSTRACT ACKNOWLEDGEMENTS

CONTENTS 1.0 SECTION 1 – BACKGROUND AND INTRODUCTION...................... 6

2.0 SECTION 2 – LITERATURE REVIEW AND RESEARCH.................. 8

2.1. Aircraft Noise in the United Kingdom.............................................. 8

2.1.1. The Wilson Committee Report......................................................... 8

2.1.2. Second Survey of Aircraft Noise Annoyance Around London

(Heathrow) Airport........................................................................................ 16

2.1.3. The Noise and Number Index System........................................... 17

2.1.4. Changes to the Daytime Index for Aircraft Noise........................... 17

2.1.5. Planning Policy Guidance Note 24: Planning and Noise ............... 20

2.1.6. White Paper – The Future of Air Transport.................................... 22

2.1.7. Brief History of the Development of Heathrow Airport ................... 24

2.2. Aircraft Noise in the United States of America and Canada........ 25

2.2.1. The United States of America........................................................ 25

2.2.2. Canada .......................................................................................... 26

2.3. Aircraft Noise in Australia .............................................................. 27

2.4. Aircraft Noise in the European Union............................................ 35

2.4.1. An Inventory of Current European Methodologies and Procedures

for Environmental Noise Management......................................................... 35

2.4.2. Directive 2002/49/EC..................................................................... 44

2.5. Aircraft Noise Modelling ................................................................. 45

2.5.1. USA FAA Integrated Noise Model (INM) ....................................... 45

2.5.2. UK CAA ANCON ........................................................................... 45

2.5.3. Australian Transparent Noise Information Package ...................... 46

2.6. Summary of Aircraft Noise Assessment Methods ....................... 46

2.6.1. Canada: Noise Exposure Forecast (NEF) ..................................... 47

2.6.2. Australia: Australian Noise Exposure Forecast (ANEF)................. 48

2.6.3. USA: Day-Night Average Sound Level (DNL)................................ 49

2.6.4. USA: Community Noise Equivalent Level (CNEL)......................... 50

2.6.5. European Union Lden and Lnight....................................................... 52

2.6.6. United Kingdom LAeq,16hr and LAeq,8hr .............................................. 53

3.0 SECTION 3 – NOISE MODELLING OF AIRCRAFT OPERATIONS AT A ‘TYPICAL’ AIRPORT ......................................................................... 54

3.1. Introduction ..................................................................................... 54

3.2. The Noise Metrics to be Further Investigated............................... 54

3.3. The Hypothetical Airport and its Operations ................................ 54

3.4. Overview of Utilisation of the Integrated Noise Model................. 59

3.5. Results of the Computer Modelling............................................... 61

3.5.1. Canada: Noise Exposure Forecast (NEF) ..................................... 61

3.5.2. Australia: Australian Noise Exposure Forecast (ANEF)................. 62

3.5.3. USA: Day-Night Average Sound Level (DNL)................................ 63

3.5.4. USA: Community Noise Equivalent Level (CNEL)......................... 64

3.5.5. European Union: Lden..................................................................... 65

3.5.6. European Union: Lnight.................................................................... 66

3.5.7. United Kingdom: LAeq,16hr ............................................................... 67

3.5.8. United Kingdom: LAeq,8hr................................................................. 68

3.5.9. Comparison of Residential Planning Criteria in Different Regions. 70

3.6. Discussion of Results..................................................................... 74

4.0 SECTION 4 – SUMMARY, CONCLUSIONS AND AREAS FOR FURTHER WORK ....................................................................................... 76

5.0 SECTION 5 – REFERENCES........................................................... 78

APPENDICES

Appendix 1: Photographs of Examples of Aircraft Used for Noise Models

Appendix 2: 16 Hour Day Scenario INM Input Data


Appendix 4: Utilisation of Integrated Noise Model Software

Appendix 5: Resultant Noise Contours from Modelling Exercise

Methods of Assessment of Aircraft Noise Nigel Burton

1.0 SECTION 1 – BACKGROUND AND INTRODUCTION

Since their development, the modern world has rapidly learnt to rely heavily

on motorised vehicles. Coupled with their obvious benefits in terms of

transportation of goods and people come a number of consequential

disadvantages. Environmental issues, such as noise, continue to gain

exposure in the media as the growing population affected by them demand a

response from those polluting the atmosphere in which they live.

With the emphasis being placed upon the polluters to be accountable for their

actions, and authorities such as the European Union requiring all member

countries to develop maps of environmental noise in populated areas,

methods for the measurement, prediction and assessment of environmental

noise issues are coming under increasing scrutiny. The use of specific

methods will therefore require justification and their reliability to be

demonstrated and proven.

Both historically and internationally a variety of methods have been adopted

for the assessment of aircraft noise. The first objective of this project is to

examine a number of the most common methods adopted in the past and at

present as well as identifying new methods proposed for future use. The

philosophy behind these methods will be considered and their respective

advantages and disadvantages in gauging the problems caused by aircraft

noise examined.

The second part of the project will involve the use of aircraft operations data

at a theoretical airport in order to examine the different results that can be

presented by the use of different noise descriptors. The Integrated Noise

Model (INM) software produced by the Federal Aviation Authority (FAA) in

the United States will be used for this purpose. The results of this modelling

exercise will be analysed to determine which methods produce the worst

case and best case scenarios.

Section 1 – Background and Introduction 6


In order to restrict the scope of this project, the investigation will concentrate

on conventional fixed wing civilian aircraft and as such will not focus on the

effects of helicopters, military or supersonic aircraft.

Section 1 – Background and Introduction 7


2.0 SECTION 2 – LITERATURE REVIEW AND RESEARCH

2.1. Aircraft Noise in the United Kingdom 2.1.1. The Wilson Committee Report

Over forty years ago, in July 1963, the British Parliament was presented with

the findings of the Committee for the Problem of Noise in their final report.1

The Committee, often referred to as the Wilson Committee after its chairman

Sir Alan Wilson, were appointed in April 1960 “to examine the nature,

sources and effects of the problem of noise and to advise what further

measures can be taken to mitigate it”. The Committee’s fourteen chapter

report covers a variety of noise and noise related issues and includes a

chapter dedicated to the topic of aircraft noise. This is often cited as the first

major published work on the subject particularly within the United Kingdom.

The report identified that the first major introduction of aircraft operations in

the UK was that of military aircraft during the Second World War. After the

war, the civil aviation industry began to grow from a small base of a handful

of airfields/airports. In the beginning, piston-engined aircraft dominated the

skies but as time went on these were replaced by turbo-propeller (turbo-prop)

aircraft. Although complaints did occur in the early days, noise appeared

only to be a problem in the close vicinity around airports. This was to change

with the introduction of turbo-jet aircraft in 1958. These aircraft were much

larger in size than had previously been experienced, thus requiring more

power to get them off the ground. The jet engines also produced a

characteristic noise signature which was unfamiliar to those experienced in

the past. Both of these factors are cited as reasons for the steep rise in

noise related complaints.

Even at this early date the report recognised that “there is ample evidence

that aircraft noise causes much annoyance. Government Departments,

Members of Parliament, local authorities and airfield authorities receive

numerous complaints”. Since the issue of aircraft noise was in its infancy,

Section 2 – Literature Review and Research 8


the committee held a number of its meetings at Heathrow Airport in order to

experience the problem first hand. The committee also requested that two

investigations be undertaken; first, “an experiment on the acceptability of

aircraft noise” and second, “a social survey in the vicinity of London

(Heathrow) Airport”. These are discussed later in this section.

In order to understand the situation in the civil aviation industry at the time,

the committee focussed its attention on Heathrow Airport as this was seen to

be “the busiest international airport in Great Britain and provides one of the

most difficult aircraft noise problems in the world”. The committee reported

that studies regarding the airport had discovered that most complaints related

to take off and landing noise, that complaints were greatest near the airport

and close to take off and landing routes and that, per 100 movements, heavy

jet-engined aircraft produced the most complaints. Whilst most complaints

were from individuals, public figures and bodies such as Members of

Parliament and Local Authorities also voiced their concerns. Despite the

obvious problem of aircraft noise, it was noted that there was still a high

demand for housing in the areas close to the airport. This was principally

attributed to the opportunities of employment at the airport. As well as

affecting people in their homes, the report recognised that aircraft noise could

impinge on the communications of those working or studying in the area and

could have detrimental affects on patients and staff in hospitals. The Ministry

of Health recognised the problems in hospitals and ordered that new

buildings in badly affected areas would be designed to reduce the noise

experienced internally with the use of upgraded glazing and mechanical

ventilation, etc. One of Her Majesty’s Inspectors of Schools noted that on a

visit to a school in the Heathrow area a half hour assembly was interrupted

by aircraft noise a total of ten times on the first day of their visit and that on

the second day was abandoned. It is reported that experiments were being

undertaken to improve the sound insulation and that new schools in areas

where aircraft noise may “seriously affect school activities” should be located

in quiet areas and arranged and built to provide reasonable protection

against noise.



In relation to the legal position of those affected by aircraft noise, it is

reported that “Sections 40 and 41 of the Civil Aviation Act, 1949, broadly

prohibit actions for nuisance arising from civil aircraft in flight or on

aerodromes”. Due to the restriction on legal action the Minister for Aviation

at the time considered “himself under an obligation to take steps to minimise

the nuisance” caused by aircraft noise.

A number of methods of reducing the noise problem are discussed including

the reduction of noise at source, take-off, landing and ground running

procedures as well as methods of monitoring the noise. Increasing work in

research and development was being carried out to address the problem of

aircraft noise. It was reported that most jet aircraft that used Heathrow were

fitted with suppressors which whilst reducing the noise level increased

running costs “since they reduce take off thrust, and increase fuel

consumption, drag and weight”. At the time, most new jets that were coming

into service employed bypass or ducted fan jet engines. These were found

to be 10-12 dB quieter than the conventional jet engines but that little

additional attenuation could be achieved with the use of suppressors in these

cases. Continuing work into reducing the whine of compressors, the principal

cause of annoyance when aircraft came into land, was also carried out.

The committee reported that the maximum permissible take off noise levels

of jet-engined aircraft should be no higher than for larger piston-engined

aircraft. This statement proved problematic since piston-engined aircraft

varied in noise level and it was felt to be unfair to use the noisiest of these

aircraft as a benchmark. It was also recognised that the characteristic noise

produced by jet-engined aircraft should be taken into account. These

problems were examined by the Port of New York Authority and research

“based upon human judgements of a number of piston-engined and jet-

engined aircraft” culminated in the creation of a new noise metric, the

Perceived Noise Level which was rated in PNdB. The Port of New York

Authority adopted a limit of 112 PNdB (roughly comparable with 98 dBA), a

figure which was exceeded by 25 per cent of larger piston engined aircraft

still in operation. Heathrow adopted a slightly lower figure of 110 PNdB



(equivalent to about 96 dBA). Following the implementation of the limit,

aircraft operators were not permitted to introduce scheduled services at

Heathrow without indicating that they could ensure that their aircraft would

not exceed the limit at predefined “first built-up areas” after take off. Initially

no scheduled operations were permitted during the night-time period, taken

as 23:00-07:00 hr, but delayed aircraft would be permitted to take off only if

they proved “high compliance” with the 110 PNdB limit. Any aircraft wishing

to depart after midnight would need to prove a much lower limit, generally

102 PNdB (around 88 dBA). However, from 1 April 1960 a number of

scheduled services were permitted to operate during the night-time period

providing that compliance with the 102 PNdB limit was proven. The

Committee reported that airlines could achieve the new limits in a number of

ways, most choosing to use full power to achieve a steep climb before

reducing power before reaching the “first main built-up area”. To achieve

this, many operators found that they needed to reduce their take off load,

often requiring them to carry less fuel and therefore requiring an additional

refuelling stop elsewhere.

The Committee’s report details the methods adopted by Heathrow Airport to

monitor the noise produced by its aircraft operations. Manual monitoring at

an area immediately before first main built-up area captured around 90% of

all take offs by jet-engined aircraft whilst a proposed automatic system was

capable of recording 100% of take offs. The results of the monitoring were

analysed and explanations sought for “serious or persistent non-compliance”

with the adopted limits. Instead of banning operators or pilots, the Airport

promoted cooperation with offenders to conform to the limits in future. This

methodology clearly worked with only 2% of all measured jet aircraft

exceeding the limits between January and August 1962. This result was

seen as commendable due to the high level of skill required by pilots in order

to conform to the limits. In August 1961, the Airport adopted a number of

new take off routes in an attempt to avoid densely populated areas. The

Committee noted that these efforts would not assist those living close to the

Airport or before the first main built-up areas, and that the limits did not apply



to propeller-engined aircraft many of which made more noise than

jet-engined aircraft.

As methods to improve the noise performance of departing aircraft were

implemented, the Airport received increasing numbers of complaints relating

to jet-engined aircraft on approach. Improvements in this area were seen as

complex since requiring aircraft to approach at a steeper angle could

jeopardise safety. It was noted that the 3° minimum approach angle was

rarely breeched.

An important issue that was addressed was the fact that aircraft in flight did

not pose the only noise problem at and around airports. It was reported that

Heathrow was a major maintenance base where essential ground running

operations, coupled with their consequential noise, were required to take

place. A number of methods of reducing this ground running noise were

discussed including keeping ground running to a minimum (particularly during

the night-time period), the construction of noise screens and earth bunds and

the use of mufflers to attenuate the noise of jet engines. It was noted that at

Heathrow Airport most of these methods had been implemented by the

Airport at significant cost but that only a small number of complaints were

then received relating to ground running, some of which were understood to

relate to aircraft taxiing. In order to achieve further reductions in complaints it

was suggested that aircraft could be towed around the apron instead of

taxiing under their own power. This suggestion was rejected since it was felt

that the reduction in noise “would not counterbalance” the problems caused

to the Airport and the operators by such procedures. A valuable point raised

was that jet-engined aircraft did not require running up in order to reach

operating temperature before take off, where as piston-engined aircraft did.

The Committee asked the Ministry of Aviation to poll the opinions of other

international airports on the issues of noise. The findings were that most

considered noise as a “grave problem” and that the majority of complaints

related to jet-engined aircraft, particularly on take off, and that night flights



produced a “proportionately greater amount of disturbance than day flights”.

A variety of different methods were employed by other airports to alleviate

the problems of noise, all of which were already in use at Heathrow. The

Committee reported that “it proved impossible to make detailed comparisons

between the problems at Heathrow and other airports” due to the differences

in circumstances at each airport. It was noted that, although aircraft noise

was unpopular, if too strict a line were imposed upon operators at Heathrow

such that their profitability dropped significantly, they might move their

operations to other European airports. The Committee remarked that “a

substantial reduction in air services to Heathrow, which serves London and,

indeed, the whole country, would have a grave deleterious effect on the

country’s economy”.

The Committee goes on to discuss the problems with noise that could occur

in the future. It recognised that the medium and long range jet-engined

aircraft that operated at the time from Heathrow accounted for a minority of

aircraft movements but that with the advent of smaller, short range jet

engined aircraft to replace short range propeller engined aircraft would see a

substantial increase in jet-engined aircraft movements. It was forecast that

the average of 60 jet-engined aircraft movements per day in 1960 would

increase to 260 per day by 1965 and 440 per day by 1970. These increases

were likely to lead to increases in annoyance and disturbance around

Heathrow Airport but that similar problems were likely to occur at other

airports such as Ringway (Manchester) and Prestwick in Scotland. With

regard to night-time operations in the future it was reported that pressure

from airlines to allow jet-engined aircraft operations at night in order to

maximise aircraft usage, thus increasing profitability as well as easing

congestion at Heathrow during the daytime, was influencing decisions on

Airport policy. Due to factors such as safety, improvements in landing noise

would necessitate reductions in the noise produced by the aircraft and their

engines. As described earlier in the report, through engine development

noise reductions of the order of 10-12 dB were being achieved. However,

the Committee warned that if operators decided to use extra power whilst

remaining within airport limits, the net reduction experienced on the ground



may be minimal. In addition it was noted that it might take several years for

these new breed of quieter aircraft to completely replace the older, noisier

aircraft so the benefits may take some time to come into fruition.

In order to allow them to gain a greater insight into the problems associated

with aircraft noise, the Committee asked for two investigations to be carried

out. The first was to establish the acceptability of aircraft noise by a “jury”

and the second was a survey of the population in the locality of Heathrow

Airport. Initially an additional experiment to investigate the health effects of

noise on local residents was also requested. Upon advice from both the

Medical Research Council and local doctors that it would be difficult to

produce meaningful results and that no significant effects had been

observed, the request for this investigation was withdrawn.

The “experiment on the level of noise which is acceptable” was carried out by

the National Physical Laboratory at Farnborough in 1961. The Committee’s

report states that “60 people were asked, under different conditions on each

of three days, to make subjective judgements of noises of a number of

different types of aircraft, including jet and propeller-driven machines and

helicopters”. The main conclusions that were drawn were that judgement of

noisiness related to previous experience of the responder to the source and

that a scale of “intrusiveness” could be formed.

The objectives of the social survey around Heathrow Airport were:

• “to ascertain the effects of the noise on the activities of people living

within a 10 mile radius of the airport”

• to assess “the amount of disturbance and annoyance caused to these

people”

• to discover “whether they considered that any advantage accrued to

them from the presence of the airport”

• and “to provide information from which an assessment could be made

of the tolerability of the noise to people living in the area”.



Noise measurements were also carried out in the areas inhabited by the

respondents in order to draw comparisons with the survey results. Several

conclusions were drawn from the results of this experiment. It was found that

there was good correlation between historical complaints and the “degree of

annoyance” recorded by the survey. Large variations in responses to aircraft

noise meant that significant changes would be required in the level and/or

character in order to provoke a significant change in response. Importantly it

was discovered that there was a link between annoyance and increases in

either noise level or aircraft or the number of aircraft movements. This

conclusion led to the creation of the Noise and Number Index, the underlying

principle of which was that annoyance could be kept constant if aircraft noise

levels increased so long as the number of movements decreased, and vice

versa.

In addition to these experiments, the Building Research Station, now known

as the Building Research Establishment, carried out an investigation into the

possibilities of improving sound insulation of houses. The results of the

investigation were that the introduction of double windows and suitably

attenuated mechanical ventilation to conventionally single glazed properties

could produce an improvement in the reduction of aircraft noise from 20 to

40 dB.

The Committee reported that between 20,000 and 40,000 people in the area

around Heathrow were subjected to more noise than they could reasonably

be expected to tolerate and that the problem would not get better, and could

get significantly worse, unless action was taken. Two methods to improve or

at least maintain the current situation were suggested; the reduction of noise

produced by aircraft types or the provision of improved sound insulation to

local homes. The consequences of each of these suggestions was

discussed in some detail and, with regard to the latter, considerations on

grant qualification, sources of finance for improvement works and

implications for new dwelling were presented.



On reflection of the obvious problems that already existed at Heathrow, the

Committee recommended that lessons learnt at this airport should be used at

other airports. It was noted that since there were no sparsely populated

areas in the UK, serious consideration would be required for the location of

new airports or the expansion of existing sites.

2.1.2. Second Survey of Aircraft Noise Annoyance Around London

(Heathrow) Airport

In 1967, the Board of Trade commissioned a “Second Survey of Aircraft

Noise Annoyance Around London (Heathrow) Airport”2. The brief for this

follow-up work was “to re-examine and to extend the findings of the 1961

survey in order to provide information which would help ministers to make

decisions regarding noise control around airports”. The report of the new

survey noted that, in general, middle class people were more annoyed by

aircraft noise than those of working class and that middle aged and elderly

people were more annoyed than younger people. It was concluded that the

results of the new survey indicated “no increase in annoyance due to aircraft

noise”. Two explanations were presented for this result; 1) that people had

become more familiar with aircraft operations and their resulting noise and 2)

that although there had been a significant increase in the number of aircraft

operations taking place, there had only been a slight increase in aircraft

loudness. The latter was consolidated by a finding that whilst the degree of

annoyance in relation to loudness had stayed the same as that recorded in

1961, there was a marked drop in the level of annoyance in relation to the

number of aircraft. From this finding it was reported that “This throws

considerable doubt on the trade off, in annoyance terms, between noise and

number as inferred from the ‘Noise & Number Index’”.

Similar analysis to that carried out in 1961 was undertaken with the results of

the new survey and similar results were found. More respondents said that

they had become used to the noise of aircraft than said they had become

more sensitive despite the fact that noise levels had increased. The survey

also found that people who had lived in the area and experienced the



increase in noise level were more critical than people who had recently

moved into the area.

2.1.3. The Noise and Number Index System

As discussed earlier, the Noise and Number Index metric was developed as

a result of the survey work carried out for the Wilson Committee into the

community reaction to Aircraft Noise. It is calculated using 3: Equation 2.1.1

Equation 2.1.1

80Nlog15LNNI 10PNmax −+=

where

LPnmax = Logarithmic average of the highest levels of all

overflights

N = number of aircraft flights

The subtraction of 80 within the formula relates to the findings of the social

survey carried out for the Committee which indicated that the annoyance

factor was zero at 80 PNdB.

NNI contour values of 35, 45 and 55 represented low, moderate and high

community annoyance respectively. It is understood that NNI was assessed

with regards to operations between mid June and mid October during the

hours of 06:00 and 18:00 hrs only.

2.1.4. Changes to the Daytime Index for Aircraft Noise

Little changed with regards to the assessment of aircraft noise in the United

Kingdom until the early 1980s when the Noise and Number Index was

coming under increasing criticism. The criticisms included the fact that NNI

was out of date, was not easily comparable with other national systems, was

only valid for Heathrow for which it was formulated and as such was



unsuitable for new airports, that it ignored any events under 80 PNdB, and

that it made no allowance for the duration of individual events. As a result of

these and other criticisms, the Department of Transport commissioned the

Civil Aviation Authority’s (CAA) Directorate of Research and Analysis

(DORA) to “Substantiate the NNI or, if necessary, to devise some better

index for Aircraft Noise”. As such, DORA carried out the “United Kingdom

Aircraft Noise Index Study (ANIS)” and published their results in January

19854. As with the earlier Wilson study, the ANIS carried out both noise

measurements and a social survey; although in contrast to the work in the

1960s, the ANIS examined the effects at a total of five airports (Heathrow,

Gatwick, Luton, Manchester and Aberdeen) instead of the effects at

Heathrow Airport alone. “Common Noise Exposure Areas” commonly of

around 1 square km were chosen with noise measurements being carried out

at a central site within the area and approximately “80 randomly chosen

residents” being surveyed using a questionnaire based on those originally

devised in the 1960s. A total of 26 such areas were examined with a total of

2097 questionnaire responses. The main findings of the ANIS were as

follows:

• The Study was successful in “disentangling the effects of aircraft noise

level and number”

• The “Guttman Annoyance Scale” was found to be a good measure of

disturbance and agreed “well with other scales used in the questionnaire”.

• The “Trade-Off” factor of 15 used in the NNI expression was found to

place too much weight on the number of aircraft. It was suggested that “a

value of 9 or 10” would be better.

• It was concluded that noise events below the 80 PNdB “cut-off” should be

included as should evening and night-time movements, although without

weighting as used in other countries.

• 24 hour LAeq was found to provide a good fit to disturbance responses.

• The issue of people having a professional involvement with an airport (i.e.

“people who work at or who have business with the airport”) was

estimated to lower the percentage of response of aircraft noise being “not

acceptable” by 25%.



• There were found to be no significant “airport dependent” responses

based on the results from the five airports under examination.

• Whilst the historical use of NNI was unlikely to have “led to major

distortions in the environmental picture” its continued use would lead to

problems, for example with increasing numbers of modern aircraft being

ignored due to their noise level being below the 80 PN dB “cut-off”.

• It was suggested that 55 and 70 dB LAeq,24hr could be used to represent

the “onset of community annoyance” and the “point of high disturbance”

respectively.

The proposed change from NNI to LAeq,24hr was then put out to public

consultation, the results of which indicated that whilst the majority (80%) of

the respondents agreed with the use of an Leq based system, many felt the

24 hour averaging time suggested by DORA was inappropriate for the

assessment of daytime noise. Following the completion of the consultation

process, in September 1990, the Department of Transport announced that

they were to replace the Noise and Number Index (NNI) method adopted in

the mid-sixties with Leq,16hr5. Whilst NNI contours had been produced for

major airports for some years, in the future these would be replaced by

LAeq,16hr contours. In order to promote greater understanding of the new

system, both NNI and LAeq,16hr contours were produced in tandem for two

years worth of data. It was found that contour levels for each system

corresponded as shown in Table 2.1.1 below:

LAeq,16hr (dB) NNI (PNdB)

57 35

60 40

63 45

66 50

69 55

72 60

Table 2.1.1: LAeq,16hr and NNI Comparison



Also in September 1990, the DORA produced a report entitled “The Use of

Leq as an Aircraft Noise Index”6. This report included an analysis of the

issues raised in the ANIS consultation as well as detailing how the new Leq

index would be implemented.

2.1.5. Planning Policy Guidance Note 24: Planning and Noise

In September 1994, the then Department of Environment published PPG 24,

a Planning Policy Guidance Note related to Planning and Noise7. The note

states the following:

“Planning policy guidance notes set out the Government’s policies on

different aspects of planning. Local authorities must take their content into

account in preparing their development plans. They may be material to

decisions on individual planning applications and appeals.”

PPG 24 introduced the concept of Noise Exposure Categories (NEC’s)

ranging from A-D to help local authorities in their consideration of

applications for residential development near to transport and industrial

related noise sources. The different categories are as defined in Table 2.1.2

below.



NEC

A Noise need not be considered as a determining factor in granting

planning permission, although the noise level at the high end of the

category should not be regarded as desirable

B Noise should be taken into account when determining planning

applications and, where appropriate, conditions imposed to ensure an

adequate level of protection against noise.

C Planning permission should not normally be granted. Where it is

considered that permission should be given, for example because there

are not alternative quieter sites available, conditions should be imposed

to ensure a commensurate level of protection against noise.

D Planning permission should normally be refused.

Table 2.1.2: Definitions of PPG 24 Noise Exposure Categories

PPG 24 provides recommended noise exposure categories for new dwellings

near existing noise sources. The noise levels with regards to aircraft noise

are reproduced in Table 2.1.3 below.

NOISE LEVELS CORRESPONDING TO THE NOISE EXPOSURE

CATEGORIES FOR NEW DWELLINGS LAeq,T dB

NOISE EXPOSURE CATEGORY

Noise Source A B C D

Air Traffic

07.00 – 23.00

23.00 – 07.00

<57

<48

57-66

48-57

66-72

57-66

>72

>66

Table 2.1.3: PPG 24 Recommended NECs w.r.t. Air Traffic

Additional guidance is also provided with regards to night-time noise events

as follows:

“Night-time noise levels (23.00-07.00): sites where individual noise events

regularly exceed 82 dB LAmax (S time weighting) several times in any hour



should be treated as being in NEC C, regardless of the LAeq,8h (except where

the LAeq,8h already puts the site in NEC D).”

2.1.6. White Paper – The Future of Air Transport

In December 2003, the Department of Transport published a white paper

entitled “The Future of Air Transport”8. The white paper states the

Government’s position with regards to “the development of airport capacity in

the United Kingdom over the next 30 years”. Prior to the publication of the

white paper, seven regional consultation documents were published from

which 500,000 responses were received. Just as air travel from and within

the UK has increased to 500% of what it was 30 years ago, it is widely

accepted that air travel is likely to increase in the future. Although aircraft

today are significantly quieter than the early jets in the 1960’s, the predicted

future growth in air traffic could easily exceed the noise reduction techniques

introduced thus leading to an increase in noise levels. Whilst the

Government encourages the obvious economic benefits such as employment

and exportation that air travel brings, it recognises that these should be

balanced with the consequential environmental impacts that result. With

regards to noise, the Government have set out an aim “to limit and, where

possible, reduce the number of people significantly affected by aircraft noise”.

One of the practical suggestions offered to assist in achieving this aim is to

place “limits on the size of the area around major airports affected by

significant noise level”.

The Government also intends implementing EU Directive 2002/49/EC. This

directive “requires periodic noise mapping at many airports from 2007 to

identify day and night noise problems and, from 2008, action plans to deal

with them”. This directive is discussed in more detail in Section 2.4.2.

As well as the noise section, the white paper also contains a section on

“Noise mitigation and compensation”. Within this section, the Government

sets out its three tiered approach to noise impacts;



1. to control the scale of impacts

2. to mitigate remaining impacts

3. to compensate for those impacts which cannot be mitigated

It is suggested that a percentage of the “large economic benefits provided by

airport development” should go towards the mitigation of the development’s

impact in the local area. Whilst voluntary schemes, such as acoustic

insulation grant schemes, are encouraged the Government has drawn up a

“benchmark for mitigating aircraft noise” which should be adopted by the

larger UK airports (defined as those operating in excess of 50,000

movements a year).

With “immediate effect”, the Government expects such airports to offer

households exposed to high aircraft noise levels (defined as “69 dBA Leq or

more”) financial assistance with regards to relocation. It also expects the

offer of acoustic insulation in areas of medium to high aircraft noise levels

(defined as “63 dBA Leq or more”) not only to residential properties but also to

other noise sensitive buildings, for example schools and hospitals. In order

to determine where such measures will be required, airports where noise

contouring programmes are not currently used are encouraged to do so in an

effort to verify the “current noise levels”. In instances where acoustic

insulation “cannot provide an appropriate or cost-effective solution”, airports

are expected to provide alternative assistance. Examples of such

alternatives include provision of quiet rooms for reading or music,

environmental grants and funding for school trips away from the noisy

environment.

The document also states what is expected of these larger airports following

future airport growth. In areas exposed to in excess of 69 dBA Leq which

have also been subject a “large increase in noise” (defined as 3 dBA Leq or

more), airports should offer to purchase properties. Acoustic insulation

should be offered in areas exposed to 63 dBA Leq or above which have also

suffered a large increase in noise, as defined above.



The white paper indicates the use of 2002 noise contours as the base year

for the assessment of impact of future growth at these larger airports and that

further contours should be produced at a minimum of five yearly intervals.

Airports which are not currently considered “large” should use the year when

the first operate in excess of 50,000 movements as their base year, with

further contours being produced at a minimum of five yearly intervals.

2.1.7. Brief History of the Development of Heathrow Airport

Various sources present similar accounts of the origins of Heathrow

Airport9,10,11,12,13. It is reported that the airport was originally known as the

Great Western Aerodrome and was owned by the Fairey Company. The

aerodrome was mainly used for test flights with the vast majority of

commercial flights operating from the nearby Heston and Hanworth Airfields.

It is reported that the aerodrome was requisitioned by the Air Ministry for use

by the RAF in 1944 but that no military activities ever took place before it was

transferred to the Ministry of Civil Aviation on 1 January 1946. Heathrow

Airport was formally opened on 31 May 1946 with an army surplus tent

operating as a terminal, a short distance from the single runway. By 1947,

three runways were complete but it was not until some eight years later that

the first terminal building, now known as Terminal 2, was finished. This was

followed by the construction of “Oceanic” terminal (Now Terminal 3) and

Terminal 1, opened in 1968. The popularity of the Airport led to the opening

of a further terminal, Terminal 4, in 1986.

The modern day Heathrow Airport is a far cry from its modest beginnings. In

1946, the new airport operated a mere 9,000 flights to just 18 destinations.

In the year 2000-2001, Heathrow operated 450,000 flights, 50 times more

than in 1946, to 170 destinations with services being provided by 90 airlines

to 64,000,000 passengers.

Amidst much controversy and fervent objection on 20 November 2001, after

a public enquiry lasting 3 years 10 months, the government granted

permission for the construction of a fifth terminal at Heathrow Airport.



Terminal 5 has been designed to cope with a further 30,000,000 passengers

using the Airport each year.

2.2. Aircraft Noise in the United States of America and Canada

2.2.1. The United States of America

Due to the state government system operated within the United States of

America there are a number of different noise assessment systems and

criteria that have been adopted across the country. This said, the body

ultimately responsible for the control and management of aircraft and airports

throughout the USA is the Federal Aviation Administration (FAA). Part 150 of

the Federation Aviation Regulations (FAR) “Airport Noise Compatibility

Planning” sets out standards by which airports must report the noise

exposure produced by their operations and methods by which to “minimise

noise-related land use incompatibilities”14. Research by this Author indicates

that there are two major noise metrics accepted under the current

regulations; the Day-Night Average Sound Level and the Community Noise

Equivalent Level.

The Day-Night Average Sound Level (DNL), often referred to as LDN, is, in

essence, the average noise level for a 24 hour period with the events

occurring during the night-time period of 22:00 to 07:00 hrs being given an

increased weighting. The imposed night-time weighting is justified by the

“added intrusiveness of night-time noise events attributable to the fact that

community background noise levels typically decrease at night”14. The

majority of federal agencies dealing with noise have formally adopted DNL as

a metric for assessing noise exposure with the Federal Interagency

Committee on Noise (FICON) stating in 1992 that “There are no new

descriptors or metrics of sufficient scientific standing to substitute for the

present DNL cumulative noise exposure metric”15. Although DNL can be

measured the procedure is time consuming. As such, the majority of airport

noise studies rely heavily on computer modelled DNL contours. Part 150

requires that the DNL contour values of 65, 70 and 75 dB be produced.



The Community Noise Equivalent Level (CNEL), often referred to as LDEN,

follows a similar rationale to the DNL but also includes an increased

weighting for events occurring during the evening period of 19:00 to 22:00 hr.

The CNEL was developed in the State of California and has been adopted,

with the consent of the FAA, as the standard for the assessment of

cumulative noise exposure within the region. The contour levels to be

produced for CNEL are understood to be similar to those required by the

DNL since the two metrics are considered to be interchangeable.

Results from 18 surveys carried out worldwide indicated that DNL/CNEL

levels as low as 55 related to around 5 percent of people becoming highly

annoyed16. It was noted that the percentage of highly annoyed people rose

sharply above around DNL/CNEL 65.

It is understood that other metrics such as the Noise Exposure Forecast

system and the Composite Noise Rating system have also been used for the

assessment of aircraft noise within the United States but that their use is now

generally redundant.

2.2.2. Canada

In order to obtain information relating to the assessment of aircraft noise in

Canada, this Author contacted Mr Tom Lowrey of Transport Canada17.

According to Mr Lowrey the Noise Exposure Forecast (NEF) system has

been used in Canada since the early 1970s. The relevant publication in this

case is TP 1247E – Land Use in the Vicinity of Airports, Part IV of which is

entitled “Aircraft Noise”18. The NEF system, originally developed in the

United States of America, is based on the Effective Perceived Noise Level

metric (EPNL). This metric, along with its corresponding criteria as adopted

in Canada, is described in more detail in Section 2.6.1.



Mr Lowrey also explained that Transport Canada operate their own aircraft

noise modelling software which, under review, “compared favourably, within

approximately 5% or better, with major systems in use throughout the world”.

2.3. Aircraft Noise in Australia

Since 1982, the Australian government has used the Australian Noise

Exposure Forecast (ANEF) system as their metric of choice for the

assessment of aircraft noise. The ANEF system, which is based on the

Noise Exposure Forecast (NEF) system developed in the United States of

America in the late 1960’s, was developed following an investigation of the

impact of aircraft noise on residential communities in Australia carried out by

the National Acoustic Laboratories (NAL) in 197919. The ANEF system is

discussed in more detail in Section 2.6.2.

In 1994, Sydney Kingsford-Smith Airport opened its third runway. Following

the opening, residents in areas predicted not to be affected during the

planning stage found themselves being disturbed by aircraft noise. Due to

the great magnitude of publicity that surrounded the case a Senate Select

Committee was formed to examine the issue of aircraft noise in Sydney. In

relation to the Third Runway project, the Select Committee’s report criticised

the way in which the future aircraft noise had been depicted in the

Environmental Impact Statement (EIS)20. Whilst the EIS had used the

conventional tool of the time for the region, the Australian Noise Exposure

Forecast (ANEF), many people felt that they had not been provided with a

fair representation of what, how, and to what extent, the aircraft noise was to

affect them.

As a result of the Committee’s findings, the Australian Department of

Transport and Regional Services undertook an investigation of different

methods of aircraft noise assessment. In March 2000, the Department

published a discussion paper entitled “Expanding Ways to Describe and

Assess Aircraft Noise”21. The document was produced to “promote debate

on the development and use of more transparent approaches to describing



and assessing aircraft noise around Australian airports”. The paper makes

the suggestion that in order to allow aircraft noise to be better understood by

the layperson, it should be described in terminology that relates to the most

common questions asked by the layperson in connection with aircraft noise.

It suggested that members of the public were often interested in answers to

the following questions:

• “Where will the flight paths be?”

• “How many aircraft will use the flight paths?”

• “At what time will I get the noise – during the day, early morning,

evenings or weekends?”

• “What will it be like on the ‘bad’ days?

• “Will I get more noise in the summer?”

• “Will the largest and noisiest aircraft fly over my area?”

• “Will I get take-offs or landings over my houses?”

• “When will I get a break from the noise?”

Whilst the questions may be simple, the conventional use of providing ANEF

contours on their own does not give explicit answers to any of them. The

paper was careful not to reject or dismiss the use of ANEF system but

instead proposed that supplementing its use with other metrics should

improve understanding of the impacts surrounding the introduction of or

proposed changes to aircraft operations.

Four main methods of presenting the level of aircraft noise are described.

These are as follows:

1. Flight Paths and Movement Numbers

2. Respite

3. The N70

4. The Person-Events Index and The Average Individual Exposure



Flight Paths and Movement Numbers

When looking at buying homes near airports people often examine flight path

data in order to assist them with their task. It is assumed that if a property is

under a flight path it will be noisy, and if not it will be quiet. Whilst this is an

oversimplification of the situation the basic principle is correct. The level of

air traffic utilising the different flight paths is also a major factor that will affect

the level of noise received on the ground. To answer questions such as

“where do the aircraft fly” and “how many overflights are there”, the use of

flight path movement charts has been developed.

Unlike traditional flight path plans which show individual thin lines for each

path, those shown on the new charts get wider as they get further away from

the airport. This displays the natural dispersion of aircraft in flight and

dispelling the myth of aircraft flying along “railway tracks in the sky”. In

addition, the charts include: data for each path on the average number of

daily movements; the number of jet aircraft utilising the route as a percentage

of the total number of jet aircraft movements; the daily range (i.e. min and

max) of aircraft movements along the route; and the percentage of days with

no movements.

The discussion paper states that these types of charts have been used at

Sydney Airport since 1998 and have been well received. However,

limitations of this method have been identified. These include the fact that

there is no dissemination between small and large aircraft (all are taken to be

similar) and that the wider paths, showing more dispersion, are often wrongly

interpreted as noisier in comparison with narrower paths where flights are

concentrated over a smaller area.

Respite

A significant problem with the use of the LAeq metric or similar system is that

they assume that annoyance levels will remain the same if the number of

aircraft operations are doubled so long as the individual aircraft noise levels



are reduced by 3 dB. Whilst a reduction of 3 dB for an individual aircraft

event may only just be noticeable, a doubling of movements is likely to have

a far greater effect.

With this in mind, and as the number of aircraft movements increases, as

they have in recent years and are predicted to in the future, the layperson is

interested to know when they will have a break from the noise, hence the

idea of specifying respite. In Australia, “extensive debate” took place over

the most effective way to define respite. Examination was made of the

threshold noise level and the time period over which no aircraft events occur.

Due to difficulties with definitions and computation the use of a specific

threshold noise level was not feasible. Instead, flight path usage was utilised

for the purposes of respite description. This still left the issue of what time

period should be used. The approach adopted by Sydney Kingsford-Smith

Airport for their monthly monitoring report was to calculate the number of

whole clock hours when no movements occurred on a given flight path. This

figure is then presented as a percentage of the total number of clock hours in

the period under examination. The example offered is that “if there were no

movements on a particular flight path during 50 clock hours in a 100 hour

clock period then it would be reported as ‘Respite Hours 50%’”. A clock hour

is, for example, between 07:00 and 08:00 or 10:00 and 11:00, etc.

The respite hours are calculated for the following four periods:

a) Morning Respite: 06:00-07:00 hrs (Weekdays)

b) Evening Respite: 20:00-23:00 hrs (Weekdays)

c) Weekend Respite: 06:00-23:00 hrs (Saturday or Sunday)

d) Daytime Respite: 07:00-20:00 hrs (Weekdays)

Periods a), b) and c) have been identified as sensitive times. The night-time

period is not a prominent issue at Sydney Airport due to it’s strictly enforced

curfew hence the lack of information relating to 23:00-06:00 hrs.

Consideration has been given to producing a single figure for respite at a

particular location by weighting and then combining the results for the various



time periods. To date, this has been avoided since, it is felt, it would reduce

the clarity of the information.

Respite charts have not been as well received as the flight path and

movement charts described earlier. One criticism of the technique and its

use in Sydney has been that certain areas may be close to more than one

flight path. This would mean that whilst no aircraft might be operating on the

nearest route to a particular location, it might still be affected by noise from

activity on other routes. This problem is likely to be particularly prevalent at

locations close to an airport. No obvious solution has been found for this

problem though it is noted that “for most parts of Sydney the charts give a

very good indication of the extent to which respite is being achieved”.

Another problem with the system in its current form is that the use of clock

hours can lead to an underestimation of respite. The example given is that “if

there were one movement at 12:05pm and one movement at 1:55pm no

respite would be recorded for that two hour period. This would be despite the

fact that for virtually all that period (110 minutes) there were no movements”.

Based on the predicted increase in aircraft movements in the future, the

issue of respite from aircraft is one that will not go away and therefore

requires further investigation and research.

The N70

Due to some of the apparent shortcomings of the ANEF system, discussions

took place in Sydney between the airport and the various local communities

to find the best way to provide an easily comprehensible method to describe

actual aircraft noise levels. After trialling the use of SEL footprints for

individual aircraft it was found that to provide such information for all aircraft

types, on all routes, and including information on the number of movements

was unworkable. Instead, ‘Number Above’ contours were proposed.

The N70 indicates the number of aircraft movements that exceed 70 dB(A)

SEL at a given location. Locations with similar numbers of aircraft



movements that exceed 70 dB(A) SEL, i.e. locations with similar N70 results,

are joined together to provide the various N70 contours. The N70 is by no

means a new concept but has been around for over 20 years and was

examined in a study carried out by the National Acoustic Laboratory in

Australia in 198222.

The Australian Standard AS202123 specifies the single event level of 60

dB(A) as “the indoor design sound level for normal domestic areas in

dwellings” since this is the level at which “a noise event is likely to interfere

with conversation or with listening to the radio or the television”. Given that a

house with partially open windows provides around 10 dB(A) attenuation of

external noise sources leads us to the rationale behind the choice of 70

dB(A) SEL for as the noise threshold, and hence the N70.

The discussion paper states that the N70 contours can and have been

produced with the aid of the United States Federal Aviation Administration’s

Integrated Noise Model (INM). Since the INM package does not offer the

calculation of N70 contours as a standard output metric, additional

computation is required. The Department of Transport and Regional

Services in Australia has now produced software for the creation of N70 and

other noise contours. This software is discussed in more detail in a later

section.

In order to deal with ‘sensitive times’, as described earlier, it is seen

appropriate to produce N70 contours for these specific time periods. It is

important to understand that ‘number above’ contours for different noise

levels can also be produced. An example of their use is the N60 contour of

which a number were produced for the 22:00 to 06:00 hrs period in the

Environmental Impact Statement for the second Sydney airport. The level of

60 dB(A) SEL chosen in that case corresponds to “the sleep disturbance

level of 50 dB(A) specified in AS2021” again allowing for 10 dB attenuation

by the fabric of the building.



The discussion paper reports various methods of producing combined N70

contours such as by applying different weightings to events, which take place

during sensitive times.

In practice, N70 contours have been produced to as low as “10 events per

day exceeding 70 dB(A) level”. It is noted, however, that whilst this covers a

significantly larger area than would be cover for a similar 20 ANEF contour,

contours produced at such a low level using the INM raise “significant

questions about the accuracy of the information”.

Due to its arithmetic nature, the N70 is easier for the layperson to understand

than other, logarithmic indicators. The example given is that “all other things

being equal, if the number of movements over an area doubles the N70

doubles”. The N70 can also be used to present the results of actual

measured noise data in addition to its use with computer model results,

which are often viewed with scepticism by the public.

One criticism of the use of N70 noted in the discussion paper is that it does

not differentiate between aircraft events of 70 dB(A) and those of higher

levels such as, for example, 90 dB(A). It is suggested that this could be

overcome by producing higher level ‘noise above’ contours e.g. N80, N90,

etc, but that this may lead to more confusion rather than improving clarity.

The Person-Events Index and The Average Individual Exposure

A useful way to assess the impact of aircraft noise is to determine the

number of people that will be affected by it. At many airports noise

preferential routing is used to divert aircraft away from greatly populated

areas. Whilst assessing the total number of people affected is important,

decisions sometimes have to be made as to whether it is worse for a small

number of people to be exposed to high noise levels or if it is worse for a

large number of people to be exposed to lower noise levels. This question

creates a problem for decision makers, many of whom will not be experts



with regards to noise, since they may not understand the differences

between the two scenarios sufficiently to make considered judgements.

To assist non-experts with interpretation of this type of information, the

Department of Transport and Regional Services in Australia has devised the

Person-Events Index (PEI). The discussion paper states that “the index is

not intended to replace existing noise indicators but to supplement them”.

The PEI is calculated using below: Equation 2.3.1

Equation 2.3.1

( ) NPxPEI N∑=

“where x = The single event threshold noise level expressed in dB(A)

PN = The number on persons exposed to N events > x dB(A)

The PEI is summed over the range between Nmin (a defined cut-off level) and

Nmax (the highest number of noise events louder than x dB(A) persons are

exposed to during the period of interest)”.

An example given in the discussion paper is that if a single departure by one

aircraft exposes 20,000 people to a single event level of 70 dB(A) or greater,

the PEI(70) would be 20,000 for that event. If an additional departure took

place, similar to the first event, then the total PEI(70) for both events

combined would be 40,000. A more detailed example of the use of PEI is

presented in the discussion paper examining different operating scenarios at

Sydney Airport.

The information provided by the PEI is not comprehensive and requires

further computation to make it so. It is very well knowing that the PEI(70) is,

for example, 1,000,000, but this could mean that one person is exposed to a

million events of 70 dB(A) or more, or it could mean that a million people are

exposed to one event of 70 dB(A) or more, or any other situation between



these two extremes. This requirement for further clarification has led to the

creation of average individual exposure (AIE) which is calculated using

below: Equation 2.3.2

Equation 2.3.2

Population Exposed TotalPEIAIE =

As with the PEI, the AIE is based on a defined minimum cut-off level of x

number of events per day.

Like the N70 described earlier, the PEI and AIE are both arithmetic and

therefore show “differences between scenarios much more starkly than

logarithmic indices which dampen any difference”.

The discussion paper notes that the PEI is useful “for computing partial noise

loads” and can produce meaningful results even one or a small number of

movements. It can also be used to compare results at different airports. It is

advised that the AIE should not generally be used for this purpose but that it

is useful “when comparing different operating scenarios at a particular

airport”.

2.4. Aircraft Noise in the European Union

Different countries in the European Union rate aircraft noise indices

differently, below are the methods currently adopted in a number of countries

or regions.

2.4.1. An Inventory of Current European Methodologies and Procedures for

Environmental Noise Management

In preparation for the European Commission’s Directive on the Assessment

and Management of Environmental Noise, and in particular the requirement



for Noise Mapping, the European Environment Agency commissioned Ian H

Flindell and Andrew R McKenzie to produce “An Inventory of Current

European Methodologies and Procedures for Environmental Noise”24. Their

findings, which were published in June 2000 included methods of

assessment of aircraft noise in 17 member states. These methods,

excluding those adopted in the UK as discussed earlier, are summarised

below:

Austria

Daytime (06:00-22:00) LAeq,16hr Contours 60, 65 and 70 dB.

Night-time (22:00-06:00) LAeq,8hr Contours 50, 55 and 60 dB.

Noise Limits based on LDN (maximum of day and night values, with 10 dB

added to the night-time values).

Planning guidance as indicated in Table 2.4.1 below:

LDN/LAmax New Buildings Existing Buildings

>75/105

Agricultural, military and airport

buildings only. No new

residential zones.

>65/-

Residential buildings in existing

zone and commercial buildings to

have required sound insulation.

No new residential zones.

Residential and noise sensitive

buildings (schools, hospitals,

nursing homes) to have required

sound insulation.

>60/- Residential buildings in existing

zone. No new residential zones.

>55/-

Noise sensitive buildings only in

case of overriding need with

required sound insulation

Noise sensitive buildings

(schools, hospitals, nursing

homes) to have required sound

insulation.

Table 2.4.1: Austrian Planning Guidance relating to Aircraft Noise

It was noted that a revised version of the reference, due for editing in 2000,

would include Lden as a “specified indicator”.



Belgium – Flanders

LDN with a 10 dB weighting for night-time period (22:00-07:00). “Zones are

established corresponding to LDN values of 55-60, 60-65, 65-70, 70-75 with

the percentages of highly annoyed people in each zone calculated from

%HA=0.0684*(LDN-42)”.

Belgium – Wallonie

Ldn - similar to LAeq with 10 dB night-time weighting (22:00-07:00). Noise

levels divided into planning zones:

“Zone A – Ldn>70

Reserved only for activities linked with the functioning of the airport. The

administration will propose to owners of dwellings in this zone to buy their

house. No new construction is admitted. No financial aid is given for

acoustic insulation.

Zone B – Ldn 65-70

In this zone, a financial aid will be proposed for the acoustic insulation of

existing dwellings. No new dwellings should be allowed in this zone.

Economic activities are admitted.

Zone C – Ldn 60-65

Financial aid will be proposed for acoustic insulation of existing dwellings.

New dwellings could be allowed, but in a very restricted way, with specific

acoustic conditions.

Zone D – Ldn 55-60

Financial aids will occur, but not for offices, sport centres and shops.

New dwellings construction will also be restricted.”

Belgium – Brussels

Levt – “Sound Exposure Level (SEL) for any individual aircraft event

LSp avion – “LAeq from all aircraft events, corrected for the effects of other

background noise sources”

Divided into zones as indicated in Table 2.4.2 below:



Zones Levt LSp avion

Daytime

(07:00-23:00)

Night-time

(23:00-07:00)

Daytime

(07:00-23:00)

Night-time

(23:00-07:00)

0 80 70 55 45

1 90 80 60 50

2 100 90 65 55

Table 2.4.2: Brussels Planning Guidance relating to Aircraft Noise

Denmark

Lden – peak three months, 5 dB weighting for evening, 10 dB weighting for

night-time. The guideline planning limits are presented in below: Table 2.4.3

Table 2.4.3: Danish Planning Guidance relating to Aircraft Noise

Area Smaller Airfield Airport or Military Airfield

Summer Residential,

Camping 45 50

Hospital, School 45-50 55

Residential 45-50 55

Hotel, Office 60 60

Rural 50 60

LAmax night-time limit: 70 dB(A) and 80 dB(A) for smaller airfields and airports

and military airfields respectively. State subsidised sound insulation for

dwellings exposed to above 65 dB LAeq.

Finland

All sources treated similarly. LAeq,d Daytime (07:00-22:00) and LAeq,n Night-

time (22:00-07:00) guidelines are presented in as follows: Table 2.4.4



Description LAeq,d LAeq,n

Residential Areas 55 50

Recreation Areas in Conglomerations and Areas in their

Proximity 55 50

Areas Serving Nursing or Educational Institutions 55 50

New Residential and Recreation Areas and Areas Serving

Nursing or Educational Institutions 55 45

Holiday Settlements (camping site etc). 45 40

Table 2.4.4: Finnish Planning Guidance relating to Aircraft Noise

France

Assessed using presented below: Equation 2.4.1

Equation 2.4.1

∑ −= 32)10log(10 1.0 iLip gI

where

Li = Noise from each operation in PNdBmax

gi = 1 for operations 06:00-22:00 and 10 for operations 22:00-06:00

Zones, and their respective maximum permitted levels are presented in

below:

Table

2.4.5



Zone Ip Permitted Development

A >=96 Residences and buildings required for aeronautical activities

and public amenities vital for existing populations

B 89-96 Residences required for individual, commercial and

agricultural activities

C 84-89

Individual non-estate housing located in already developed

sectors, refurbishing operations for districts and existing

homes provided population of noise exposed population not

signification increased

D <84 Unrestricted

Table 2.4.5: French Planning Guidance Relating to Aircraft Noise

Germany

Assessed using a modified version of LAeq entitled LAeq(4) which is calculated

using Equation 2.4.2 below:

= ∑ 3.13

101log3.13)4(i

iiAeqLtg

TL

Equation 2.4.2

where:

Li = noise level in dB(A)Smax

T = 180*86400 seconds

ti = 10 dB down time

gi = 1 (for 06:00-22:00) or 5 (for 22:00-06:00)

Zones, and their maximum permitted levels as shown in Table 2.4.6 below:



Zone LAeq(4) Permitted Development

1 >75 No new dwellings, support of insulation at existing dwellings.

No convalescent or retirement homes or schools.

2 67-75 New dwellings only with improved insulation. No

convalescent or retirement homes or schools.

3 <62 No restrictions in some federal states.

Table 2.4.6: German Planning Guidance relating to Aircraft Noise

Greece

Assessed “using Noise Exposure Forecast (NEF) based on EPNdB where,

for a particular class of aircraft i, on flight path j, producing EPNLij”. The

contribution to the NEF is calculated using Equation 2.4.3 below:

[ ] 887.16log10 10 −++= NijDijEPNiij nnLNEF

Equation 2.4.3

where:

nDij = the number of day time flights (0700-2200)

nNij = the number of night time flights (2200-0700).

The total NEF is then calculated using Equation 2.4.4 below:

= ∑∑ 10/

10 10log10 NEFij

i jNEF

Equation 2.4.4

It is reported that three zones are specified corresponding to NEF>40, NEF

30-40 and NEF <30, but that no information was provided as to what

restrictions, if any, are implemented within these zones.



Ireland

It is reported that aircraft noise is assessed in this state using the Noise and

Number Index (NNI) but that no limits were specified. NNI is calculated using


Equation 2.4.5

80log15)( −+= NLNNI avpn

Where:

Lpn(av) = average noise level in PndBmax of all operations exceeding

80 PndBmax

N = number of operations during period 0600-2200

Italy

“Lva which is a 21 day, 24 hour LAeq, with a 10 dB night-time (2300-0600)

weighting, averaged over the busiest weeks from each of the three period 1st

October to 31st January, 1st February to 31st May, and 1st June to 30th

September.

The limits for land use planning are presented in Table 2.4.7 below:

Zone Lva Permitted Development

A <=65 No restriction

B 65-75 Prohibited for Residential Use

C >=75 Only Airport Activities Allowed”

Table 2.4.7: Italian Planning Guidance relating to Aircraft Noise

Luxembourg

Assessment method believed to be similar to that in Germany i.e. LAeq(4).



The Netherlands

Aircraft noise assessed using Kosten-units which are calculated using


Equation 2.4.6

( ) 15710log20 15/ −= ∑ iLigKe

where:

Li = Max A-weighted sound level for each operation”

gi = 1 (08:00-18:00), 2 (18:00-19:00), 3 (19:00-20:00), 4 (20:00-21:00),

6 (21:00-22:00), 8 (22:00-23:00), 10 (23:00-06:00), 8 (06:00-07:00) or

4 (07:00-08:00)

“Noise limits which must not be exceeded by existing airports are” presented

in below:

Noise Level Planning Restriction

<=35 No Restrictions

>35 Generally No New Residential Areas

Allowed

>40 Generally No New Dwellings Allowed

40-50 Insulation of Existing Dwellings to NLR

30-35

50-55 Insulation of Existing Dwellings to NLR

35-40

Table 2.4.8: Dutch Planning Guidance relating to Aircraft Noise



“In addition, for smaller airport with air traffic consisting of aircraft with MTOW

< 6,000 kg, an index called BKL is used with planning restrictions above 50

BKL.”

Portugal

No specific method for assessing aircraft noise stated.

Spain

There are many regional variations in approach to aircraft noise. Reference

is made to grants being applicable for sound insulation improvements to

residential properties built prior to April 1996 where levels of aircraft noise are

above 65 dB LAeq,(0700-2300) and/or 55 dB LAeq,(2300-0700).

Sweden

Aircraft noise is assessed using Lden which is based upon LAeq with

weightings of 5 dB and 10 dB for evening (19:00-22:00) and night-time

(22:00-07:00) respectively. At aircraft noise levels of below 55 dB Lden, no

planning restrictions apply.

2.4.2. Directive 2002/49/EC

On the 25 June 2002, the European Parliament published Directive

2002/49/EC “relating to the assessment and management of environmental

noise”25. The aim of the directive is “to define a common approach … to

avoid, prevent or reduce on a prioritised basis the harmful effects, including

annoyance, due to exposure to environmental noise”. As well as making the

requirement that member states begin the production of strategic

environmental noise maps by no later than 2007, the directive also attempts

to standardise the way in which noise is reported throughout the European

Union. In an earlier green paper published by the European Parliament in

1997 it was noted that there was a “lack of reliable, comparable data



regarding the situation of various noise sources”. The directive emphasises

that in order to promote common understanding of noise issues, “data about

environmental noise levels should … be collected, collated and reported in

accordance with comparable criteria”. To this end, the directive dictates that

all member states adopt the Lden and Lnight metrics for the purpose of

reporting environmental noise levels. It is also suggested that in certain

cases it would be appropriate to also use Lday and Lnight. These metrics are

discussed in more detail in Section 2.6.5.

2.5. Aircraft Noise Modelling

It should be noted that the packages described in this section are merely a

sample of those available and that the list is by no means exhaustive.

2.5.1. USA FAA Integrated Noise Model (INM)

The United States of America Federal Aviation Authority’s Integrated Noise

Model (INM) has been used for the prediction of aircraft noise impact in the

proximity of airports since the late 1970s26. The software is available for

purchase from the FAA and, now in its sixth full version, is arguably the most

widely used software for aircraft noise modelling. Since this software is to be

used for the modelling section of this project, it will be examined in more

detail later.

2.5.2. UK CAA ANCON

The ANCON modelling software is not available for purchase but is instead

owned and operated by the CAA. This is unfortunate since, it is argued by

this Author, it means that any UK residents or organisations who wish to

model aircraft noise are forced to use another modelling package, such as

the INM, or retain the services of the CAA to use their ANCON model. In

many cases the latter is likely to be prohibitively expensive. This said, the

ANCON system is used by the government to produce regular noise contours

for the main BAA airports in the south-east of Heathrow, Stanstead and



Gatwick. Other airports such as Manchester also employ the ANCON

system to produce noise contours for the benefit of local authorities in their

area.

2.5.3. Australian Transparent Noise Information Package

In response to the publication of their discussion paper on “Expanding Ways

to Describe and Assess Aircraft Noise”21, the Australian Department of

Transport and Regional Services produced a package of computer software

applications which made it possible for “non-expert users to generate the

descriptors shown in the Discussion Paper”27 such as Flight Path Movement

Charts, Respite Charts and N70 Contours. The software can also

incorporate data produced within the INM software.

In an attempt to encourage people to use the software it has been available

as freeware and can be obtained from the department. Like other modelling

packages the software can be used to carry out ‘what if’ assessments

therefore allowing any user to analyse the effects of possible operational

changes at their local airport.

This Author has attempted to obtain a copy of this software package but alas,

to date, has not received it. It is, however, satisfying to see a major authority

undertaking to improve communication of aircraft noise issues to

non-experts. This kind of approach is likely to reduce the feelings of

resentment often felt towards conventional methods of presenting aircraft

noise due to their complicated nature and subsequent inaccessibility to the

layperson.

2.6. Summary of Aircraft Noise Assessment Methods

The following noise metrics, and their associated criteria levels, have been

selected for use in the next section of this project. The criteria specified

relate to those adopted for land use compatibility for residential dwellings in

the particular country or region stated.



2.6.1. Canada: Noise Exposure Forecast (NEF)

The Noise Exposure Forecast system was originally developed by the U.S.

Federal Aviation Agency for the assessment of community annoyance

caused by aircraft noise and is calculated using Equation 2.6.1 below28.

( ) (dB) 88N7.16Nlog10EPNLNEF ND10 −++=

Equation 2.6.1

where

EPNL = energy mean value of the EPNL

ND = number of daytime flights (07:00-22:00)

NN = number of night-time flights (22:00-07:00) – the factor of 16.7 relates

to a 10-1 weighting of night flights as opposed to day flights

In Canada the land use criteria with regards to residential development is as

shown in below: Table 2.6.1

Table 2.6.1: From Table 3 of TP 1247E – Part IV

Noise Exposure Forecast Values >40 40-35 35-30 <30

Exposure Areas 1 2 3 4

Residential

Detached, Semi-Detached No1 No1 No2 A

Town House, Garden Homes No1 No1 No2 A

Apartments No1 No1 No2 A

Where

No1 “Indicates that new construction or development of this nature should not

be undertaken”, No2 “Indicates that new construction or development of this

nature should not be undertaken (See Explanatory Note B)” and A indicates

that “This particular land use may be acceptable in accordance with the



appropriate note and subject to the limitations indicated therein”. Explanatory

Note B states that Transport Canada’s recommendation is that “New

residential construction or development should not be undertaken” in areas

subject to between NEF 30 and 35, but offers guidance for those authorities

that nevertheless wish to proceed.

Transport Canada state that “Annoyance caused by aircraft noise may begin

as low as NEF 25”. In essence, residential development will generally be

accepted in areas up to NEF 30 but may require improved acoustic insulation

of the building envelope in some cases. For the purposes of this project,

NEF 30 has been selected as the level up to which residential development

is acceptable.

2.6.2. Australia: Australian Noise Exposure Forecast (ANEF)

The Australian Noise Exposure Forecast was first introduced in Australia in

198219. This system of assessment was based on the aircraft Noise

Exposure Forecast but with refinements made based on the results of a

survey into the reaction of communities to aircraft noise in Australia. ANEF is

calculated using below: Equation 2.6.2

Equation 2.6.2

( ) (dB) 88N4Nlog10EPNLANEF ND10 −++=

where

EPNL = energy mean value of the EPNL

ND = number of daytime flights (07:00-19:00)

NN = number of night-time flights (19:00-07:00)

In Australia the land use criteria with regards to residential development is as

shown in below23: Table 2.6.2



Building Type ANEF zone of site

Acceptable Conditional Unacceptable

House, home unit,

flat, caravan park

Less than 20

ANEF (Note 1)

20 to 25 ANEF

(Note 2)

Greater than 25

ANEF

Table 2.6.2: Extract from Australian Standard AS 2021-1994

Note 1 points out that the location of the 20 ANEF contour is difficult to

accurately define “because of variations in aircraft flight paths” and as such

additional procedures may be followed for “building sites outside but near to

the 20 ANEF contour”. In relation to areas within the 20 to 25 ANEF band,

note 2 states that “some people may find that the land is not compatible with

residential or educational uses” and as such noise control features may be

appropriate. For the purposes of this project, both the 20 and 25 ANEF

contours will be evaluated.

2.6.3. USA: Day-Night Average Sound Level (DNL)

The Day-Night Average Sound Level, denoted as DNL or Ldn, is an Leq based

system which is used to rate the noise present over a 24 hour period. The

noise levels occurring during the night-time period, which in the United States

of America is the nine hour period between 22:00 hr and 07:00 hr, are given

a 10 dB weighting penalty such that the calculation of the DNL is as shown in

below29: Equation 2.6.3

Equation 2.6.3

+

=

+10

10Ln10Ld

1091015241log10DNL

where Ld = daytime (07:00 hr – 22:00 hr) LAeq,15hr

Ln = night-time (22:00 hr – 07:00 hr) LAeq,9hr



As noted earlier Part 150 of the Federal Aviation Regulations requires that

the DNL contours of 65, 70 and 75 by produced. Table 1 of Appendix A of

Part 150 describes compatible land use as a function of YDNL, Yearly Day-

Night Average Noise Level. YDNL is defined as the average of daily DNL

values throughout the year. The land use criteria with regards to residential

development is as shown below in Table 2.6.3:

Yearly Day-Night Average Sound Level

Land Use – Residential Use <65 65-

70

70-

75

75-

80

80-

85

>85

Residential other than mobile

homes and transient lodgings

Y N(1) N(1) N N N

Mobile home park Y N N N N N

Transient lodgings Y N(1) N(1) N(1) N N

Table 2.6.3: Land Use Compatibility Guidelines from FAR Part 150

Where Y means that “Land use and related structures are compatible without

restrictions” and N means that “Land use and related structures are not

compatible and should be prohibited”. Note (1) states that “Where the

community determines that residential or school uses must be allowed,

measures to achieve outdoor to indoor Noise Level Reduction (NLR) of at

least 25 dB and 30 dB should be incorporated into building codes and be

considered in individual approvals. Normal residential construction can be

expected to provide a NLR of 20 dB, thus, the reduction requirements are

often stated as 5, 10 or 15 dB over the standard construction and normally

assume mechanical ventilation and closed windows year round. However,

the use of NLR criteria will not eliminate outdoor noise problems”.

2.6.4. USA: Community Noise Equivalent Level (CNEL)

The Community Noise Equivalent Level (CNEL), sometimes referred to as

Lden, was introduced in the State of California in the Early 1970’s as a

“simplified alternative to the NEF system”30. CNEL is similar to DNL but as



well as the a 10 dB weighting being placed on all night-time movements, an

additional weighting of multiplying all movements taking place during the

evening period (19:00 hr to 22:00) by a factor of three. One method of

calculating CNEL is as presented in Equation 2.6.4 below:

( ) (dB) 4.49N10N3Nlog10SENELCNEL NED10 −+++=

Equation 2.6.4

where ND = Number of flights during the daytime (07:00-19:00 hrs)

NE = Number of flights during the evening (19:00-22:00 hrs)

NN = Number of flights during the night-time (22:00-07:00 hrs)

SENEL = The energy mean value of the single event noise exposure

as calculated using Equation 2.6.5 below:

ea10max tlog10NLSENEL +=

Equation 2.6.5

where NLmax = The maximum noise level in dB(A)

tea = The effective time duration (in seconds) of the noise level. It is

approximately equal to half of the time during which the event noise

level is within 10 dB of the maximum.

SENEL is similar to SEL but measured for the time interval whilst noise from

an aircraft exceeds a predetermined threshold level14. In general, the

SENEL result will be similar to that of the SEL.

Another method of calculating CNEL is the altered version of the DNL

formula as presented in Equation 2.6.6 below:



+

+

=

++10

10Ln10

5Le10Ld

1091031012241log10CNEL

Equation 2.6.6

where Ld = daytime (07:00 hr – 19:00 hr) LAeq,12hr

Le = evening (19:00 hr – 22:00 hr) LAeq,3hr

Ln = night-time (22:00 hr – 07:00 hr) LAeq,9hr

The FAA accepts CNEL in place of DNL for studies conducted within

California since the region has adopted CNEL as its standard for the

assessment of cumulative community noise exposures. As such, DNL and

CNEL are interchangeable and the land use criteria for residential

development described in FAR Part 150 and reproduced in Table 2.6.3 are

compatible for both metrics.

2.6.5. European Union Lden and Lnight

Directive 2002/49/EC states that the calculation of Lden is as presented in

below25: Equation 2.6.7

Equation 2.6.7

×+×+×=

++

1010L

105L

10L

den

nighteveningday

1081041012241lg10L

where Lday = “the A-weighted long-term sound level … determined

over all the day periods of a year”

Levening = “the A-weighted long-term sound level … determined

over all the evening periods of a year”

Lnight = “the A-weighted long-term sound level … determined

over all the night periods of a year”



The unit is effectively the same as CNEL but differs due to the different

durations of the day, evening and night-time periods. The European Union

allows for individual member states to “shorten the evening period be one or

two hours and lengthen the day and/or the night period accordingly”. Since

the UK currently adopts a 16 hour day and 8 hour night it is likely that the

standard form presented above will be used in this country. The Lnight is to be

taken as defined above.

The European Union requires the use of these metrics for the purposes of

assessment and noise mapping but has not set out any specific criteria for

acceptable or unacceptable levels for planning use. This said, contours of

55, 60, 65, 70 and 75 dB Lden are required for the assessment of “the

estimated number of people” exposed to such noise levels. For the same

purpose, the contours of 50, 55, 60, 65 and 70 dB Lnight are required for the

night-time period.

2.6.6. United Kingdom LAeq,16hr and LAeq,8hr

As described in Section 2.1.5, Planning Policy Guidance Note 24 states the

Government’s policy on planning with regards to noise7. The planning

criteria are detailed in that section.



3.0 SECTION 3 – NOISE MODELLING OF AIRCRAFT OPERATIONS AT A ‘TYPICAL’ AIRPORT

3.1. Introduction

For this section of the project, the noise assessment methods discussed in

Section 2.6 have been identified for further examination. The examination

will involve modelling the different metrics for the operations at a

hypothetical, yet realistic, airport. Following the modelling process the results

for each metric will be compared with each other and with their respective

criteria to determine which of them operate the most stringent and least strict

standards.

3.2. The Noise Metrics to be Further Investigated

A total of 8 noise metrics have been selected for further investigation. They,

along with their respective country or region of use in brackets, are as

follows:

• Noise Exposure Forecast, NEF (Canada)

• Australian Noise Exposure Forecast, ANEF (Australia)

• Day-Night Average Sound Level, DNL (USA)

• Community Noise Equivalent Level, CNEL (USA)

• Lden (European Union)

• Lnight (European Union)

• LAeq,16hr (United Kingdom)

• LAeq,8hr (United Kingdom)

3.3. The Hypothetical Airport and its Operations

The hypothetical airport operates a single runway which is 3050m in length.

The aircraft operations at this airport are based closely on movement data

from an existing European regional airport though the data has been

Section 3 – Noise Modelling of Operations at a ‘Typical’ Airport 54


somewhat simplified for the purposes of this assessment. The runway

designations at the airport are 09 and 27, due east and due west

respectively. Each of the two runway designations has two departure flight

paths, or routes, and one arrival path. One departure route on each runway

designation turns towards the north, whilst the other turns towards the south.

The arrival paths on each runway designation are straight in and therefore

follow the extended centreline of the runway. Figure 3.3.1 below shows the

basic layout of the runway at the airport and its departure and arrival routes.

09A 27A

27N

27S

09N

09S

Figure 3.3.1: Basic Layout of Runway and Departure and Arrival Routes

Movement data for a total of eleven different aircraft types has been

produced. The total daily movements for each aircraft type are shown in

below: Table 3.3.1



Aircraft Type Class Sector Length Total Movements

Embraer 145 1 1 66

Dash 8 1 1 66

Airbus A319 2 2 109

Airbus A320 2 3 109

Boeing 737-700 2 3 109

Boeing 737-800 2 2 109

Airbus A310 3 4 11.2

Boeing 757 3 4 22.4

Boeing 767 3 6 22.4

Airbus A300 4 5 48

Airbus A330 4 6 48

Total Number of Movements by All Aircraft 720

Table 3.3.1: Total Number of Daily Movements by Aircraft Type

The reason that some aircraft types in the table have either an odd number

or non-whole number of movements is that these figures relate to data for an

average day. Some aircraft will not fly everyday and hence the apparently

unusual input data. The class of the aircraft type relates to its size, weight

and capacity with the Airbus A300 and Airbus A330 being the largest aircraft

types to be included in this assessment. The sector length relates to the

distance that the aircraft type is going to fly. In this case, the sector lengths

relate to the profile stage number utilised by the INM, where 1 is 0 to 500

nautical miles (nmi), 2 is 500 to 1000 nmi, 3 is 1000 to 1500 nmi and 4 is

1500 to 2500 nmi. Photographs of examples of all of the aircraft types are

shown in Appendix 1.

The data in Table 3.3.1 was then divided in departures and arrivals by aircraft

type using a simple 50%/50% split, since all aircraft arriving must depart.

The departure and arrivals for each aircraft type were then split by runway

designation. In common with many UK airport, a split of 70%/30% in favour

of the western (27) routes was used. Finally, the departures on each runway

designation and for each aircraft type were split into those going north and



those going south. For the purposes of this assessment it has been

assumed that 80% of all departures turn towards the south whilst the

remaining 20% turn towards the north. These routings are not dissimilar from

those used at several UK airports due to large proportion of traffic heading

south towards mainland Europe. The results of these computations are

shown in below: Table 3.3.2

Table 3.3.2: Daily Movements split by Runway, Movement Type and Route

Aircraft Type Runway 09 (Due East) Runway 27 (Due West)

Arrival Departure Arrival Departure

09A 09N 09S 27A 27N 27S

Embraer 145 9.9000 1.9800 7.9200 23.1000 4.6200 18.4800

Dash 8 9.9000 1.9800 7.9200 23.1000 4.6200 18.4800

Airbus A319 16.3500 3.2700 13.0800 38.1500 7.6300 30.5200

Airbus A320 16.3500 3.2700 13.0800 38.1500 7.6300 30.5200

Boeing 737-700 16.3500 3.2700 13.0800 38.1500 7.6300 30.5200

Boeing 737-800 16.3500 3.2700 13.0800 38.1500 7.6300 30.5200

Airbus A310 1.6800 0.3360 1.3440 3.9200 0.7840 3.1360

Boeing 757 3.3600 0.6720 2.6880 7.8400 1.5680 6.2720

Boeing 767 3.3600 0.6720 2.6880 7.8400 1.5680 6.2720

Airbus A300 7.2000 1.4400 5.7600 16.8000 3.3600 13.4400

Airbus A330 7.2000 1.4400 5.7600 16.8000 3.3600 13.4400

Sub-total: routes 108.0 21.6 86.4 252.0 50.4 201.6

Sub-total: runway 216 504

TOTAL 720

Note: The reason for the large number of decimal places in the movement

data is that the INM works to four decimal places for its input data.

Due to the nature of many of the noise metrics to be examined, the total

number of daily movements needed to be split into the daytime, evening and

night-time periods. This creates a problem since not all of the metrics use

similar durations for these periods. For example, the LAeq,16hr system adopted



in the United Kingdom assumes the daytime period to operate between

07:00 hr and 23:00 hr whilst the US based Day-Night Average Sound Level

System assumes a daytime period between 07:00 hr and 22:00 hr, 1 hour

shorter than the UK system. Therefore, for the purposes of this project, it

was decided to model each metric using its own preferred time periods. This

has meant separating the metrics into two groups; those which operate a

15 hr day and those which operate a 16 hr day as shown in

below.

Table 3.3.3

Table 3.3.3: Groupings for Computer Modelling

Daytime Period Reference

15 Hour Day • Canadian NEF

• Australian NEF

• USA DNL

• USA CNEL

16 Hour Day • UK LAeq,16hr

• UK LAeq,8hr

• EU Lden

• EU Lnight

As a result of the two groups, it was necessary to create two separate

models, one for each scenario. The daily movement data split by runway,

movement type and route were again split, but this time by daytime, evening

and night-time movements. For simplicity it has been assumed that, for the

16 hr daytime scenario, 10% of the movements occur during the 8 hour night-

time period and that the remaining 90% are split evenly throughout the

daytime and evening hours. That is to say that the remainder is split

75%/25% between the daytime and evening periods respectively. Due to

their size, the results of these computations are presented in Appendix 2.

In order to adjust the movement data for the 15 hour daytime scenario, 25%,

i.e. 1 hours worth, of the evening movements were moved from that period to



the night-time period. The results of these computations are presented in

. Appendix 3

3.4. Overview of Utilisation of the Integrated Noise Model

A detailed explanation of the modelling practices used for this investigation is

presented in Appendix 4 whilst a summary of the most salient points is

provided below.

The Integrated Noise Model Version 6.0c has been utilised for the production

of the noise contours for this project. The software works under the Microsoft

Windows environment and can be used to calculate simple Lmax calculations

at specified locations or for more complex noise modelling processes such as

the calculation of noise contours around airports with multiple runway and

route configurations. The in-built database contains noise data for around

250 different aircraft types or variants. The software also contains layout

data for around 820 airports within the USA. For the purposes of this project,

an original study has been set up.

Table 3.4.1 below shows the information used to calculate both the

preinstalled and custom edited metrics used in this case:



Noise

Metric

Noise

Family

Metric

Type

Flight Multiplier Averaging Time

Day Eve Night (hr) (10LogT)

NEF Perceived Exposure 1 1 16.7 24 88*

ANEF Perceived Exposure 1 4 4 24 88*

DNL A-Weighted Exposure 1 1 10 24 49.37

CNEL A-Weighted Exposure 1 3 10 24 49.37

LDEN A-Weighted Exposure 1 3 10 24 49.37

LNIGHT A-Weighted Exposure 0 0 1 8 44.59

LAEQ16 A-Weighted Exposure 1 1 0 16 47.60


Table 3.4.1: INM Noise Metric Data

* The 10LogT term in the cases of NEF and ANEF is incorrect. The

figure of 88 relates to the -88 in the calculation for each of these metrics.

The INM package calculates the aircraft noise levels over a predefined area,

the grid area, and joins points of equal level in order to produce a noise

contour for that value. If the user defines a smaller grid, the low value

contours may continue outside the grid boundary. This said, if the grid is too

large, the computation time can be excessive. For the purposes of this

investigation, the standard grid size has been used and increased only when

the model has been run and it has been found that the grid size is too small.

The detail and accuracy of the contours produced is dependent upon the

“refinement” and “tolerance” settings in the “Run Options” menu. For this

investigation these were set to 9 and 0.01 respectively. These values are

different to the default values but allow for greater precision in the calculation

of the contour values, if increasing the run time slightly. Similarly, the “Low

Cutoff” and “High Cutoff” values were set to the minimum and maximum

contour values required for each metric. This allows the model to only

compute values within the required range, reducing the run time of the

model.



For the contours produced for this project, the average run time was around

2 to 3 minutes per metric. The model was run on a laptop with an AMD-K6 III

processor with around 96 MB of RAM.

Once the contours have been produced, they can be printed, to scale if

required, or can be exported as .DXF files for use in design packages such

as AutoCAD for overlaying onto geographical base maps.

3.5. Results of the Computer Modelling

The graphical results of the contours produced for each metric are presented

in Appendix 5. The results for each metric are reviewed below individually

and then compared against each other.

3.5.1. Canada: Noise Exposure Forecast (NEF)

The total areas covered by the NEF contours produced are presented in

Table 3.5.1 with the contours themselves being presented in : Figure 3.5.1

NEF Contour Value 25 30 35 40

Area within Contour (sq. km) 25.07 11.78 5.30 2.27

Table 3.5.1: Areas of NEF Contours



Figure 3.5.1: NEF Contour Outputs

Assessing our hypothetical airport using the criteria adopted in Canada,

5.30 sq.km, the area inside the 35 NEF contour, should not be used for new

residential development. The area between the 30 and 35 NEF contours

should also not be used for new residential development but Transport

Canada would offer guidance for those authorities that nevertheless wish to

proceed. The area outside the 30 ANEF contour area of 11.78 sq.km “may

be acceptable” for new residential development and is likely to be accepted

with the application of conditions, such as improved acoustic insulation, in

some cases. It is noted that “Annoyance caused by aircraft noise may begin

as low as 25 NEF”.

3.5.2. Australia: Australian Noise Exposure Forecast (ANEF)

The total areas covered by the ANEF contours produced are presented in

with the contours themselves being presented in : Table 3.5.2

Table 3.5.2: Areas of ANEF Contours

Figure 3.5.2

ANEF Contour Value 20 25

Area within Contour (sq.km) 38.56 17.22



Figure 3.5.2: ANEF Contour Outputs

Using the Australian criteria, new residential development would be deemed

unacceptable within the ANEF 25 contour area of 17.22 sq.km. Use of the

area between the 20 and 25 ANEF contours for new residential development

may be permitted but with conditions applied, such as noise control. Land

outside the ANEF 20 contour area of 38.56 sq.km would be permitted.

3.5.3. USA: Day-Night Average Sound Level (DNL)

The total areas covered by the DNL contours produced are presented in


Table 3.5.3: Areas of DNL Contours

Figure 3.5.3

DNL Contour Value 65 70 75

Area within Contour (sq.km) 10.78 4.40 1.76



Figure 3.5.3: DNL Contour Outputs

Using the United States’ criteria, new conventional residential development

will not be permitted within the DNL 75 contour area of 1.76 sq.km.

Permission should also be refused for new residences within the DNL 70

contour but in cases where permission is deemed appropriate, conditions

relating to improved sound insulation should apply. For the area outside the

DNL 65 contour area of 10.78 sq.km new residential developments would be

permitted “without restrictions”.

3.5.4. USA: Community Noise Equivalent Level (CNEL)

The total areas covered by the CNEL contours produced are presented in


Table 3.5.4: Areas of CNEL Contours

Figure 3.5.4

CNEL Contour Value 65 70 75




Figure 3.5.4: CNEL Contour Outputs

Using the State of California’s criteria, new conventional residential

development will not be permitted within the DNL 75 contour area of

1.94 sq.km. Permission should also be refused for new residences within the

DNL 70 contour but in cases where permission is deemed appropriate,

conditions relating to improved sound insulation should apply. For the area

outside the DNL 65 contour area of 11.86 sq.km new residential

developments would be permitted “without restrictions”.

3.5.5. European Union: Lden

The total areas covered by the Lden contours produced are presented in


Table 3.5.5: Areas of Lden Contours

Figure 3.5.5

Lden Contour Value 55 60 65 70 75

Area within Contour

(sq.km)

62.75 24.44 10.59 4.31 1.73



Figure 3.5.5: Lden Contour Outputs

As stated earlier, the European Union has not set out any specific criteria in

relation to these contour values. The Lden contour results will however be

compared with the criteria established in the UK later.

3.5.6. European Union: Lnight

The total areas covered by the Lnight contours produced are presented in


Table 3.5.6: Areas of Lnight Contours

Figure 3.5.6

Lnight Contour Value 50 55 60 65 70

Area within Contour

(sq.km)

29.67 12.67 5.28 2.07 0.96



Figure 3.5.6: Lnight Contour Outputs

As stated earlier, the European Union has not set out any specific criteria in

relation to these contour values. The Lnight contour results will however be

compared with the criteria established in the UK later.

3.5.7. United Kingdom: LAeq,16hr

The total areas covered by the LAeq,16hr contours produced are presented in


Table 3.5.7: Areas of LAeq,16hr Contours

Figure 3.5.7

LAeq,16hr Contour Value 57 66 72




Figure 3.5.7: LAeq,16hr Contour Outputs

Using the PPG 24 criteria adopted within the UK, for our hypothetical airport

the region within the 72 dB LAeq,16hr contour area of 1.91 sq.km would be

classified as being in Noise Exposure Category (NEC) D where “Planning

permission should normally be refused”. For the area between the 66 and

72 dB LAeq,16hr contours, NEC C, “permission should not normally be granted”

but where it is noise control conditions should be applied. For the area

between the 57 and 66 dB LAeq,16hr contours, NEC B, “Noise should be taken

into account when determining planning applications and, where appropriate,

conditions imposed to ensure an adequate level of protection”. For the

region outside the 57 dB LAeq,16hr contour area of 27.25 sq.km, NEC A, “Noise

need not be considered” with regards to awarding of planning permission.

3.5.8. United Kingdom: LAeq,8hr

The total areas covered by the LAeq,8hr contours produced are presented in

with the contours themselves being presented in : Table 3.5.8 Figure 3.5.8



LAeq,8hr Contour Value 48 57 66


Table 3.5.8: Areas of LAeq,8hr Contours

Figure 3.5.8: LAeq,8hr Contour Outputs

Using the PPG 24 criteria adopted within the UK, for our hypothetical airport

the region within the 66 dB LAeq,8hr contour area of 1.75 sq.km would be

classified as being in NEC D where “Planning permission should normally be

refused”. For the area between the 57 and 66 dB LAeq,8hr contours, NEC C,

“permission should not normally be granted” but where it is noise control

conditions should be applied. For the area between the 48 and 57 dB LAeq,8hr

contours, NEC B, “Noise should be taken into account when determining

planning applications and, where appropriate, conditions imposed to ensure

an adequate level of protection”. For the region outside the 48 dB LAeq,8hr

contour area of 43.23 sq.km, NEC A, “Noise need not be considered” with

regards to the granting of planning permission.



3.5.9. Comparison of Residential Planning Criteria in Different Regions

All of the regions, with the exception of the European Union, have residential

planning criteria with regards to aircraft noise which can be crudely simplified

into three categories:

1. Planning Permission Should Be Granted

2. Planning Permission Could Be Granted (With Conditions)

3. Planning Permission Should Be Refused

Table 3.5.9

Table 3.5.9: Areas for which Planning Permission Should Be Granted

compares the areas outside which planning permission should be

granted for each of the metrics. The colour of the text in the first column of

the table relates to the corresponding contour presented in Figure 3.5.9.

Noise Metric Criteria Area

Canada: NEF < 30 NEF Outside 11.78 sq.km

Australia: ANEF < 20 ANEF Outside 38.56 sq.km

USA: DNL < 65 DNL Outside 10.78 sq.km

USA: CNEL < 65 CNEL Outside 11.86 sq.km

UK: LAeq,16hr < 57 dB LAeq,16hr Outside 27.25 sq.km

UK: LAeq,8hr < 48 dB LAeq,8hr Outside 43.23 sq.km



Figure 3.5.9: Areas Outside Which Planning Permission Should Be Granted

Table 3.5.10

Table 3.5.10: Areas for which Planning Permission Could Be Granted (With

Conditions)

compares the region in which planning permission could be

granted with conditions for each of the metrics.


Canada: NEF 30-35 NEF 11.78-5.30 sq.km

Australia: ANEF 20-25 ANEF 38.56-17.22 sq.km

USA: DNL 65-75 DNL 10.78-1.76 sq.km

USA: CNEL 65-75 CNEL 11.86-1.94 sq.km

UK: LAeq,16hr 57-72 dB LAeq,16hr 27.25-1.91 sq.km

UK: LAeq,8hr 48-66 dB LAeq,8hr 43.23-1.75 sq.km

Table 3.5.11 compares the areas for which planning permission should be

refused for each of the metrics. The colour of the text in the first column of

the table relates to the corresponding contour presented in Figure 3.5.10.




Canada: NEF > 35 NEF Inside 5.30 sq.km

Australia: ANEF > 25 ANEF Inside 17.22 sq.km

USA: DNL > 75 DNL Inside 1.76 sq.km

USA: CNEL > 75 CNEL Inside 1.94 sq.km

UK: LAeq,16hr > 72 dB LAeq,16hr Inside 1.91 sq.km

UK: LAeq,8hr > 66 dB LAeq,8hr Inside 1.75 sq.km

Table 3.5.11: Areas for which Planning Permission Should Be Refused

Figure 3.5.10: Areas inside which Planning Permission Should Be Refused

Finally, a comparison of the residential planning criteria in the different

regions examined is presented below in the form of a cumulative bar chart in

. Figure 3.5.11



0

5

10

15

20

25

30

35

40

45

50

Canada: NEF Australia: ANEF USA: DNL USA: CNEL UK: LAeq,16hr UK: LAeq,8hr

Metric

Are

a (s

q.km

)

Permission Should Be Refused Permission Could Be Granted (With Conditions) Permission Should Be Granted

Figure 3.5.11: Comparison of Residential Planning Criteria in Different Regions



3.6. Discussion of Results

The results of the modelling exercise indicate large variations in the planning

criteria adopted in the different regions examined. The criteria adopted in

Australia appears to the be the most stringent having a comparatively large

area, 17.22 sq. km, within which residential development should be refused

on noise grounds.

Conversely, the least stringent region with regards to aircraft noise appears

to be the USA. The total areas for which development should be refused and

could be granted with conditions within this country, using either the DNL or

the CNEL system, would fit within the area for which planning permission

should be refused assuming the Australian criteria.

With regards to the UK systems, the areas within which residential

development should be refused are similar to those predicted under the USA

systems, at around 1.7 to 2.0 sq.km. This said, the UK criteria is more

stringent than the USA criteria by having a far larger area in which conditions

would be applied before residential development would be permitted without

condition.

The contour area for the 57 dB LAeq,16hr, the area outside which residential

development should be permitted within the UK, is similar to the area

encompassed by the 60 dB Lden contour under the EU system. The contour

area for the 72 dB LAeq,16hr, the area inside which residential development

should be refused within the UK, is similar to the area encompassed by the

75 dB Lden contour under the EU system. It is important to remember,

however, that this relationship is only true for this scenario since the UK

metric is based purely on 16 hour daytime and evening movements whilst the

EU system also takes account of night-time movements.

The UK LAeq,8hr and EU Lnight are identical metrics. Therefore, the nearest

Lnight contour produced to the 48 dB LAeq,8hr contour, outside which residential

development should be permitted, is the 50 dB Lnight contour. Similarly, the



nearest Lnight contour produced to the 66 dB LAeq,8hr contour, inside which

residential development should be refused, is the 65 dB Lnight.



4.0 SECTION 4 – SUMMARY, CONCLUSIONS AND AREAS FOR FURTHER WORK

It has been demonstrated that a variety of different systems have been and

are being used for assessment of aircraft noise both historically and around

the world.

Of the methods examined in the last section of this report, the Australian

ANEF system, coupled with its corresponding criteria in that country, appears

to be the most stringent, with the systems and criteria adopted in the USA

being the least strict. From the literature reviewed in Section 2, the

Australian government also appear to be actively encouraging the discussion

of aircraft noise in order to develop new methods to better communicate the

effects of aircraft operations to the layperson. The promotion of the use of

arithmetic noise metrics such as the N70 appears to be assisting this

process.

The opinion of this Author is that a common approach to the assessment of

aircraft noise would be beneficial in order to allow easy comparison of noise

exposures around different airports throughout the world. Whilst it would also

be beneficial for similar criteria to be adopted internationally, it is appreciated

that this is less likely to occur due to the apparent large variation in the

definition of what constitutes acceptable and unacceptable levels of aircraft

noise. A definitive answer as to what is and is not acceptable is unlikely to

be found since, as stated in the Department of Transport Press Notice 304 in

1990 “There is no absolute measure of disturbance from aircraft noise – nor

can there be, given the variation in individual reactions”5.

Areas that could be examined for further work in this area would include the

use and review of the new Australian aircraft noise assessment software

TNIP described in Section 2.5.3. As explained in that section, this author

attempted to obtain a copy of this freeware software but has yet to receive it.

Section 4 – Summary, Conclusions and Further Work 76


It may also be beneficial to repeat this pilot study using actual data for

various major international airports, assessing the noise exposure at each

with different noise metrics and criteria adopted elsewhere. It would also be

interesting to determine whether human response to aircraft noise exposure

differs from region to region. This could be examined by carrying out

carefully constructed surveys of people living and working around the various

airports in question, similar to those carried out on behalf of the Wilson

Committee over 40 years ago.

Section 4 – Summary, Conclusions and Further Work 77


5.0 SECTION 5 – REFERENCES 1 Committee on the Problem of Noise. Noise Final Report, HMSO, Cmnd.2056, July 1963 2 Office of Population Censuses and Surveys, Social Survey Division, Second Survey of Aircraft Noise Annoyance around London (Heathrow) Airport, 1971 3 NELSON P: Transportation Noise Reference Book Butterworths & Co. (Publishers) Ltd, 1987 4 BROOKER P, CRITCHLEY J B, MONKMAN D J, RICHMOND C: DR Report 8402 United Kingdom Aircraft Noise Index Study: main report – Civil Aviation Authority Directorate of Research and Analysis (DORA) Jan 1985 5 Department of Transport, Press Notice No 304, Change Agreed To Daytime Index for Aircraft Noise, 4 September 1990 6 CRICHLEY J B, OLLERHEAD J B: DORA Report 9023 The Use of Leq as an Aircraft Noise Index – Civil Aviation Authority Directorate of Research and Analysis (DORA) September 1990 7 DEPARTMENT OF ENVIRONMENT Planning Policy Guidance Note 24 (PPG 24): Planning and Noise September 1994 8 DEPARTMENT OF TRANSPORT The Future of Air Transport December 2002 9 http://www.uk-airportparking.co.uk/heathrow (Heathrow Airport Parking History) Accessed 27/08/03 10 http://www.heathrow.airport-parking-centre.co.uk/about-heathrow-airport.html (About Heathrow Airport - Facts, Figures and History) Accessed 27/08/03 11 http://www.heathrow-airport-parking-uk.co.uk/heathrow-history/ (Heathrow Airport History) Accessed 27/08/03 12 http://www.heathrow-airport-guide.co.uk/history.html (Heathrow Airport Guide - History of London Heathrow Airport) Accessed 27/08/03 13 http://www.parkandgo.co.uk/heathrow-airport-history.html (Park and Go: Heathrow Airport Parking – Airport History) Accessed 27/08/03 14 HARRIS MILLER MILLER & HANSON Inc: Reid-Hillview Airport FAR Part 150 Draft Noise Exposure Map 2002 15 Federal Interagency Committee on Noise (FICON) Federal Agency Review of Selected Airport Noise Analysis Issues August 1992 16 Schultz, T.J. Synthesis of Social Surveys on Noise Annoyance Journal of the Acoustical Society of America, Vol.64, No.2, August 1978 17 Personal Correspondence with Tom Lowrey of Transport Canada 18 Transport Canada, TP 1247E – Land Use in the Vicinity of Airports, Part IV – Aircraft Noise, Seventh Edition Last Amended May 1996 (http://www.tc.gc.ca/CivilAviation/Aerodrome/Environment/TP1247E/Part4/menu.htm) 19 Airservices Australia The Australian Noise Exposure Forecast System and Associated Land Use Compatibility Advice for Areas in the Vicinity of Airports, Fifth Edition September 1999 20 Senate Select Committee on Aircraft Noise in Sydney: Falling on Deaf Ears Commonwealth of Australia, Canberra, 1995 21 Department of Transport and Regional Services, Australia – Discussion Paper: Expanding Ways to Describe and Assess Aircraft Noise – March 2000 22 HEDE A J, BULLEN R B Aircraft Noise in Australia: A Survey of Community Reaction, NAL Report No.88 National Acoustic Laboratories, Australian Government Publishing Services, Canberra, 1982 23 Australian Standard AS2021-1994 Acoustics – Aircraft noise intrusion – Building siting and construction 24 FLINDELL I H, MCKENZIE A R European Environment Agency – Technical Report – An Inventory of Current European Methodologies and Procedures for Environmental Noise Management – 26 June 2000 – European Environment Agency, Denmark 25 European Parliament Directive 2002/49/EC of the European Parliament and of the Council of 25 June 2002 relating to the assessment and management of environmental noise June 2002 26 GULDING, OLMSTEAD, BRYAN, MIRSKY, FLEMING, D’APRILE, GERBI Integrated Noise Model 6.0 User’s Manual Federal Aviation Administration September 1999

Section 5 – References 78

http://www.uk-airportparking.co.uk/heathrow

http://www.heathrow.airport-parking-centre.co.uk/about-heathrow-airport.html

http://www.heathrow-airport-parking-uk.co.uk/heathrow-history/

http://www.heathrow-airport-guide.co.uk/history.html

http://www.parkandgo.co.uk/heathrow-airport-history.html

http://www.tc.gc.ca/CivilAviation/Aerodrome/Environment/TP1247E/Part4/menu.htm


Section 5 – References 79

27 Department of Transport and Regional Services, Australia – TNIP Transparent Noise Information Package – User’s Manual TNIP v3.2.2 – December 2003 28 http://www.sfu.ca/sonic-studio/handbook/Noise_Exposure_Forecast.html (Noise_Exposure_Forecast - Noise Exposure Forecast (NEF)) Accessed 22/09/03 29 http://www.netvista.net/~hpb/epa1974/epa19741.html (Equivalent Sound Level and Its Relationship to Other Noise Measures) Accessed 25/01/04 30 http://www2.sfu.ca/sonic-studio/handbook/Community_Noise_Equivalent.html (Community Noise Equivalent Level (CNEL)) Accessed 06/01/04

http://www.sfu.ca/sonic-studio/handbook/Noise_Exposure_Forecast.html

http://www.netvista.net/~hpb/epa1974/epa19741.html

http://www2.sfu.ca/sonic-studio/handbook/Community_Noise_Equivalent.html

Embraer 145 Dash 8

Airbus A319 Airbus A320

Boeing 737-700 Boeing 737-800


Page 1 of 2

Airbus A310 Boeing 757

Boeing 767 Airbus A300

Airbus A330


Page 2 of 2

ARR DEP DEP ARR DEP DEPINM Type Sector 9 09N 09S 27 27N 27S

737700 3 11.0363 2.2073 8.8290 25.7513 5.1503 20.6010737800 2 11.0363 2.2073 8.8290 25.7513 5.1503 20.6010757RR 4 2.2680 0.4536 1.8144 5.2920 1.0584 4.2336767JT9 6 2.2680 0.4536 1.8144 5.2920 1.0584 4.2336A30062 5 4.8600 0.9720 3.8880 11.3400 2.2680 9.0720A310 4 1.1340 0.2268 0.9072 2.6460 0.5292 2.1168A319 2 11.0363 2.2073 8.8290 25.7513 5.1503 20.6010

A32023 3 11.0363 2.2073 8.8290 25.7513 5.1503 20.6010A33034 6 4.8600 0.9720 3.8880 11.3400 2.2680 9.0720DHC830 1 6.6825 1.3365 5.3460 15.5925 3.1185 12.4740EMB145 1 6.6825 1.3365 5.3460 15.5925 3.1185 12.4740

72.9000 14.5800 58.3200 170.1000 34.0200 136.0800


737700 3 2.7591 0.5518 2.2073 6.4378 1.2876 5.1503737800 2 2.7591 0.5518 2.2073 6.4378 1.2876 5.1503757RR 4 0.5670 0.1134 0.4536 1.3230 0.2646 1.0584767JT9 6 0.5670 0.1134 0.4536 1.3230 0.2646 1.0584A30062 5 1.2150 0.2430 0.9720 2.8350 0.5670 2.2680A310 4 0.2835 0.0567 0.2268 0.6615 0.1323 0.5292A319 2 2.7591 0.5518 2.2073 6.4378 1.2876 5.1503

A32023 3 2.7591 0.5518 2.2073 6.4378 1.2876 5.1503A33034 6 1.2150 0.2430 0.9720 2.8350 0.5670 2.2680DHC830 1 1.6706 0.3341 1.3365 3.8981 0.7796 3.1185EMB145 1 1.6706 0.3341 1.3365 3.8981 0.7796 3.1185

18.2250 3.6450 14.5800 42.5250 8.5050 34.0200


737700 3 2.5547 0.5109 2.0438 5.9609 1.1922 4.7688737800 2 2.5547 0.5109 2.0438 5.9609 1.1922 4.7688757RR 4 0.5250 0.1050 0.4200 1.2250 0.2450 0.9800767JT9 6 0.5250 0.1050 0.4200 1.2250 0.2450 0.9800A30062 5 1.1250 0.2250 0.9000 2.6250 0.5250 2.1000A310 4 0.2625 0.0525 0.2100 0.6125 0.1225 0.4900A319 2 2.5547 0.5109 2.0438 5.9609 1.1922 4.7688

A32023 3 2.5547 0.5109 2.0438 5.9609 1.1922 4.7688A33034 6 1.1250 0.2250 0.9000 2.6250 0.5250 2.1000DHC830 1 1.5469 0.3094 1.2375 3.6094 0.7219 2.8875EMB145 1 1.5469 0.3094 1.2375 3.6094 0.7219 2.8875

16.8750 3.3750 13.5000 39.3750 7.8750 31.5000

112.5

EVENING (19:00-22:00)

36.45 85.05121.5

For DNL, CNEL, NEF and ANEF

NIGHT-TIME (22:00-07:00)

33.75 78.75

DAYTIME (07:00-19:00)

145.8 340.2486



737700 3 11.0363 2.2073 8.8290 25.7513 5.1503 20.6010737800 2 11.0363 2.2073 8.8290 25.7513 5.1503 20.6010757RR 4 2.2680 0.4536 1.8144 5.2920 1.0584 4.2336767JT9 6 2.2680 0.4536 1.8144 5.2920 1.0584 4.2336A30062 5 4.8600 0.9720 3.8880 11.3400 2.2680 9.0720A310 4 1.1340 0.2268 0.9072 2.6460 0.5292 2.1168A319 2 11.0363 2.2073 8.8290 25.7513 5.1503 20.6010

A32023 3 11.0363 2.2073 8.8290 25.7513 5.1503 20.6010A33034 6 4.8600 0.9720 3.8880 11.3400 2.2680 9.0720DHC830 1 6.6825 1.3365 5.3460 15.5925 3.1185 12.4740EMB145 1 6.6825 1.3365 5.3460 15.5925 3.1185 12.4740

72.9000 14.5800 58.3200 170.1000 34.0200 136.0800


737700 3 2.7591 0.5518 2.2073 6.4378 1.2876 5.1503737800 2 2.7591 0.5518 2.2073 6.4378 1.2876 5.1503757RR 4 0.5670 0.1134 0.4536 1.3230 0.2646 1.0584767JT9 6 0.5670 0.1134 0.4536 1.3230 0.2646 1.0584A30062 5 1.2150 0.2430 0.9720 2.8350 0.5670 2.2680A310 4 0.2835 0.0567 0.2268 0.6615 0.1323 0.5292A319 2 2.7591 0.5518 2.2073 6.4378 1.2876 5.1503

A32023 3 2.7591 0.5518 2.2073 6.4378 1.2876 5.1503A33034 6 1.2150 0.2430 0.9720 2.8350 0.5670 2.2680DHC830 1 1.6706 0.3341 1.3365 3.8981 0.7796 3.1185EMB145 1 1.6706 0.3341 1.3365 3.8981 0.7796 3.1185

18.2250 3.6450 14.5800 42.5250 8.5050 34.0200


737700 3 2.5547 0.5109 2.0438 5.9609 1.1922 4.7688737800 2 2.5547 0.5109 2.0438 5.9609 1.1922 4.7688757RR 4 0.5250 0.1050 0.4200 1.2250 0.2450 0.9800767JT9 6 0.5250 0.1050 0.4200 1.2250 0.2450 0.9800A30062 5 1.1250 0.2250 0.9000 2.6250 0.5250 2.1000A310 4 0.2625 0.0525 0.2100 0.6125 0.1225 0.4900A319 2 2.5547 0.5109 2.0438 5.9609 1.1922 4.7688

A32023 3 2.5547 0.5109 2.0438 5.9609 1.1922 4.7688A33034 6 1.1250 0.2250 0.9000 2.6250 0.5250 2.1000DHC830 1 1.5469 0.3094 1.2375 3.6094 0.7219 2.8875EMB145 1 1.5469 0.3094 1.2375 3.6094 0.7219 2.8875

16.8750 3.3750 13.5000 39.3750 7.8750 31.5000

112.5

EVENING (19:00-22:00)

36.45 85.05121.5

For DNL, CNEL, NEF and ANEF

NIGHT-TIME (22:00-07:00)

33.75 78.75

DAYTIME (07:00-19:00)

145.8 340.2486


Appendix 4: Utilisation of Integrated Noise Model Software

The Integrated Noise Model Version 6.0c has been utilised for the production of

the noise contours for this project. The software works under the Microsoft

Windows environment and can be used to calculate simple Lmax calculations at

specified locations or more complex noise modelling such as the calculation of

noise contours around airports with multiple runway and route configurations.

The in-built database contains noise data for around 250 different aircraft types

or variants. The software also contains layout data for around 820 airports

within the USA. For the purposes of this project, an original study is to be set

up, the basic processes of which are described below. It should be noted that

the software has many more functions than have been used or described here.

Creating the “Study”

The “Study” is the airport, in this can our hypothetical airport, at which the

operations take place.

• When the INM software has loaded, the “New Study” function is selected

from the “File” menu.

• The “New Study” dialogue box appears where you are prompted to enter a

“New Study Name” of no more than 30 characters as well as specifying the

directory path where the study will be saved. Click “OK”

• Upon completion, you are asked “Do you want to create a new study in” and

then the path name. Click “Yes”

• Next, you are asked to “Select the units to use for your study” where the

options of “English System” or “Metric System” are presented. In this case,

we will choose the latter and click “OK”

• The “Study Setup” screen then appears where a description of the study can

be typed. The “Origin of Coordinates” screen can be used if a preinstalled

US airport is to be selected from the databases or the “latitude”, “longitude”

Appendix 4: Utilisation of Integrated Noise Model Software 1

and “elevation” of the airport are to be specified. None of these features are

to be used on this occasion. If a US airport were selected, information such

as the coordinates, runway ends, etc, would be loaded at this point.

Choosing the Aircraft for the “Study”

• Now that the “Study” is set-up, the aircraft that operate from the Airport can

be selected. Under the “Setup” menu, select “Aircraft”.

• The Aircraft Setup dialogue box appears. From the “INM Standard Aircraft”

on the left hand side of the screen, select each required aircraft by

highlighting the choice followed by the “Include” button. The chosen aircraft

type will then move from the left hand box to the right hand “Study Aircraft”

box.

• If the required aircraft cannot be found in the list on the left hand side, the

INM manual can be consulted to find a suitable “substitute aircraft”. This is

not required in this case.

• When all the required aircraft have been moved to the “Study Aircraft” box,

click “OK”. Following this action, an “Aircraft” box will appear with details of

the chosen aircraft such as take off and landing weight, noise stage, etc.

Setting up the Runways and Routes

• From the “Tracks” menu, select the “Runway Identifiers” option.

• If a preloaded US airport has already been selected, the information in this

section will already have been loaded. In this case we will input this

information from scratch.

• The “Runway Identifiers” dialogue box is empty by default. To add a runway,

the user must press Ctrl + A. The user must then select names for “Runway

End #1” and “Runway End #2” and determine the width of the runway in

metres, followed by Ctrl + Enter to commit the details to the software. In this


case, the runway ends have been named “09” and “27” and a runway width

of 50m has been chosen.

• If additional runways are required, press Ctrl + A, else close the dialogue

box.

• Next, select the “Runway Ends” option from the “Tracks” menu. The

dialogue box will appear where the user can determine the location of the

runway ends in relation to the origin and edit other parameters such as

displaced thresholds, glide slope, etc. In this case, the centre of the runway

has been taken as the origin and runs east to west. Therefore the location of

the “09” end is –1.5250 km from the origin on the x-axis and 0 km from the

origin on the y-axis whilst the “27” end is +1.5250 km from the origin on the

x-axis and 0 km from the origin on the y-axis, thus the runway is 3050m in

length. No displaced thresholds have been specified and the standard

glideslope of 3° has been adopted. Close the dialogue box.

• Now select the “Track Identifiers” option from the “Tracks” menu. A dialogue

box appears in which the tracks for each runway can be specified. In this

case we have specified one arrival and two departure tracks for each

runway. Other options such as “sub-track” and “percentage operations” can

also be detailed here but have not been used on this occasion. Close the

dialogue box.

• Finally select the “Track Segments” option from the “Tracks” menu. Here the

user can specify the paths that each track will follow. For straight tracks,

such as the arrival routes in this case, a single straight segment is sufficient.

For the curved departure routes a total of three segments have been used

for each; one straight section followed by a turn followed by a straight

section. When inputting a turn, the angle and radius of the turn are specified.

In this case, all the routes turn through 90° with a turn radius of 5 km. Close

the dialogue box.


Setting up the Metrics

• This section need only be viewed if, as in this case, custom metrics that are

not installed within the software are required.

• From the “Setup” menu, select the “metrics” option. A dialogue box will

appear containing the inbuilt metrics. These are ‘greyed out’ such that they

cannot be edited. Each metric has a title, or “Metric ID” and belongs to a

noise “Family” and metric “Type”. The families are “A-weighted”,

“C-weighted” and “Tone-Corrected” and the types are “Exposure Based”,

“Maximum Level” and “Time-Above Based”. Each metric also has three

“Flight Multipliers” and an “Averaging Time”. The flight multipliers relate to

the different weighting given to daytime, evening and night-time movements.

The averaging time, specified as 10 LOG T in seconds, relates to the time

period over which the metric is averaged, eg 24 hours, 15 hours, etc.

• To add new metrics, press Ctrl + A and fill in the relevant information. Table

A below shows the information used to calculate both the preinstalled and

custom edited metrics used in this case:

Noise

Metric

Noise

Family

Metric

Type

Flight Multiplier Averaging Time

Day Eve Night (hr) (10LogT)

NEF Perceived Exposure 1 1 16.7 24 88*

ANEF Perceived Exposure 1 4 4 24 88*

DNL A-Weighted Exposure 1 1 10 24 49.37

CNEL A-Weighted Exposure 1 3 10 24 49.37

LDEN A-Weighted Exposure 1 3 10 24 49.37

LNIGHT A-Weighted Exposure 0 0 1 8 44.59



Table A: INM Noise Metric Data


* The 10LogT term in the cases of NEF and ANEF is incorrect. The figure of

88 relates to the -88 in the calculation for each of these metrics.

• Close the dialogue box

Creating Cases and Inputting Aircraft Movement Data

• Under the “Setup” menu, select the “Cases” Option. A dialogue box will

appear where a new case can be set-up by pressing Ctrl + A. The user must

enter a “Case ID” and a short description can also be input. “Airport

Parameters” such as temperature and headwind can be edited at this stage

but the default settings have been used in this case. For the purposes of this

exercise, two cases have been set up entitled “15 hour Day Scenario” and

“16 hour Day Scenario”. After inputting the information for a case, the user

should press Ctrl + Enter to commit the case information to the software.

Close the dialogue box.

• Under the “Ops” menu, select the “Flight Operations”. A dialogue box will

appear where the user must select which case to enter the flight operations.

Select the desired case by highlighting it and click “OK”.

• The “Flight Operations” dialogue box for the chosen case will appear. Here

the user can enter flight information for the daytime, evening and night-time

periods by aircraft type, runway, operation and route. The stage length of

the aircraft departures can also be specified under the “Profile ID” option. To

input data, the user must press Ctrl + A, enter the data for that aircraft type,

runway, etc and then press Ctrl + Enter to commit the record to the software.

This process is repeated for all the aircraft types, operations, route and

runways.

• With a large amount of data to be input, as in this case, this can be a rather

arduous task. Although the INM software saves this information as database

files, no simpler way of entering this information has been found by this

author.


• Upon completion of data entry for this case, the dialogue box should be

closed. If another case is required, as is for this assessment, the process

should be repeated.

• If cases are very similar, cases can be copied using the “Case Copy”

function under the “Setup” menu.

Running the Cases

• Once the input data is complete, the INM package must be set up to run the

cases. Under the “Run” menu, select the “Grid Setup” option. A dialogue

box will appear where the user must select which case is required. Select

the desired case by highlighting it and click “OK”.

• The Grid is basically the area over which the INM package will calculate the

noise levels of the aircraft. If it is too small, the low value contours may

continue outside the grid boundary. This said, if the grid is too large, the

computation time could be very long. In this case, the standard grid size has

been used and increased only when the model has been run and it has been

found that the grid size is too small. To add a grid, press Ctrl + A, and select

either a “Contour”, “Standard”, “Detailed”, “Location” or Population grid. For

the purposes of creating contours for this assessment, a Contour grid has

been chosen. The grid size can be adjusted by editing the “Grid Origin” and

the “Distance Between Points” option. Close the dialogue box.

• Next select “Run Options” from the “Run” menu. The “Run Options” dialogue

box will appear in which the noise metrics to be run for each of the cases can

be specified. Cases can be run for “Single-Metric” or “Multi-Metric”

scenarios. On this occasion the cases have been run for single metrics and

re-run for each metric. The “Do contours” options is highlighted and the

“refinement” and “tolerance” set to 9 and 0.01 respectively. These are

different to the default values but allow for greater precision in the calculation

of the contour values, if increasing the run time slightly. The “Low Cutoff”



and “High Cutoff” values are then set to the minimum and maximum contour

values required. Close the dialogue box.

• From the “Output” menu, select the “Output Setup” option. This is where the

contour values to be produced are selected. The case for which the outputs

are required should be highlighted in the left hand box and “Metric” and

“Contour Levels” specified. The metric should be similar to that specified in

the “Run Options” menu and the maximum and minimum contour levels

should be between the low and high cutoff values. The increments between

contours should also be set at this point. Whilst increments of, for instance,

1 dB could be set, it will increase processing time and in reality we are

usually only interested in increments of say 3 or 5 dB. Close the dialogue

box.

• We are now ready to run the case(s). Select the “Run Start” option from the

“Run” menu. A dialogue box will appear in which the user can select the

cases to be included, in a similar fashion to the way in which the aircraft for

the study were chosen. Upon selection, click “OK”. The INM software will

now run the chosen case(s) whilst showing a “percentage done” value. For

the contours for this project, the average run time was around 2 to 3 minutes

on a laptop with an AMD-K6 III processor with around 96 MB of RAM.

• When the case(s) has/have been run, the contours can be viewed by

selecting the “Output Graphics” option from the “Output” menu. Again, the

user is asked to specify the output from which case are to be viewed. Select

the desired case and press “OK”. At this stage the contours have not be

computed, merely the noise levels across the grid. The contours are now

calculated and appear in a window on the screen.

• From the “Contour Display Control” dialogue box the colour and fill of the

contours can be altered as well as the inclusion or exclusion of contour

labels. From the “File” menu the contours can be printed, to scale if

required, or can be exported as .DXF files for use in design packages such

as AutoCAD.

APPENDIX 5

RESULTANT NOISE CONTOURS FROM MODELLING EXERCISE

INM 6.1 30-Jan-04 12:02INM 6.1 30-Jan-04 12:0215 Hr Day Scenario OUT15 Hr Day Scenario OUTScale 1 cm = 500 mScale 1 cm = 500 m

NEFNEFsq.kmsq.kmcolorcolor

25.025.025.0725.07

30.030.011.7811.78

35.035.05.305.30

40.040.02.272.27


ANEFANEFsq.kmsq.kmcolorcolor

20.020.038.5638.56

25.025.017.2217.22


DNLDNLsq.kmsq.kmcolorcolor

65.065.010.7810.78

70.070.04.404.40

75.075.01.761.76


CNELCNELsq.kmsq.kmcolorcolor

65.065.011.8611.86

70.070.04.904.90

75.075.01.941.94


LDENLDENsq.kmsq.kmcolorcolor

55.055.062.7562.75

60.060.024.4424.44

65.065.010.5910.59

70.070.04.314.31

75.075.01.731.73


LNIGHTLNIGHTsq.kmsq.kmcolorcolor

50.050.029.6729.67

55.055.012.6712.67

60.060.05.285.28

65.065.02.072.07

70.070.00.960.96


LAEQ16LAEQ16sq.kmsq.kmcolorcolor

57.057.027.2527.25

66.066.05.825.82

72.072.01.911.91


LAEQ8LAEQ8sq.kmsq.kmcolorcolor

48.048.043.2343.23

57.057.09.039.03

66.066.01.751.75

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Methods of Assessment of Aircraft Noise - Acoustics

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