Methods of Assessment of Aircraft Noise - Acoustics

London South Bank UniversityDepartment of Engineering SystemsMSc in Environmental and Architectural AcousticsMETHODS OF ASSESSMENT OF AIRCRAFT NOISEN J S Burton2004A project in partial fulfilment of the requirements of the degree of Master ofScience in Environmental and Architectural Acoustics

ABSTRACTThis project examines various methods used for the assessment of aircraftnoise adopted both historically and internationally. The project is divided intotwo parts.The first part of the project examines a number of the most common methodsfor the assessment of aircraft noise adopted in the past and at present aswell as identifying new methods proposed for future use. The philosophybehind these methods is considered and their respective advantages anddisadvantages in gauging the problems caused by aircraft noise examined.The second part of the project involves the computer modelling of aircraftnoise resulting from operations at a theoretical airport using a number of thedifferent noise descriptors examined in the first part of the project. Theresults of the noise modelling, and the planning criteria adopted in theirrespective country or region of origin, are been compared to identify whichmethods produce the worst case and best case scenarios.The results of the modelling exercise indicate that the Australian systemoperates the most stringent controls with regards to aircraft noise andresidential planning whilst the systems adopted in the USA are the leaststrict.

ACKNOWLEDGEMENTSI would like to acknowledge and thank the following for their kind assistanceand support during the preparation of this thesis:• Professor Bridget Shield of London South Bank University for herassistance in refining the scope of this project and her guidance onsources of previous research material.• Dr Stephen Dance of London South Bank University for hisencouragement, supervision and for reading through the numerousdrafts.• Bickerdike Allen Partners for providing the tools and the time for me tocomplete this project and, in particular, Mr Jeff Charles for readingseveral drafts and imparting his knowledge and offering hisconstructive criticism.• Mr Tom Lowrey of Transport Canada for providing information on themethods of assessment of aircraft noise in Canada.• Mr Jonathan Firth, Mr Nick Fisher and Ms Donna Perera of theDepartment of Transport and Regional Services in Australia forproviding information on the methods of assessment of aircraft noisein Australia.• My parents, Mr John and Mrs Evelyn Burton, and my fiancée,Miss Lesley Kemp, for their unconditional love, unfailing support andfor attempting to understand what this is all about.

ABSTRACTACKNOWLEDGEMENTSCONTENTS1.0 SECTION 1 – BACKGROUND AND INTRODUCTION ...................... 62.0 SECTION 2 – LITERATURE REVIEW AND RESEARCH.................. 82.1. Aircraft Noise in the United Kingdom.............................................. 82.1.1. The Wilson Committee Report......................................................... 82.1.2. Second Survey of Aircraft Noise Annoyance Around London(Heathrow) Airport........................................................................................ 162.1.3. The Noise and Number Index System........................................... 172.1.4. Changes to the Daytime Index for Aircraft Noise........................... 172.1.5. Planning Policy Guidance Note 24: Planning and Noise ............... 202.1.6. White Paper – The Future of Air Transport.................................... 222.1.7. Brief History of the Development of Heathrow Airport ................... 242.2. Aircraft Noise in the United States of America and Canada........ 252.2.1. The United States of America........................................................ 252.2.2. Canada .......................................................................................... 262.3. Aircraft Noise in Australia .............................................................. 272.4. Aircraft Noise in the European Union............................................ 352.4.1. An Inventory of Current European Methodologies and Proceduresfor Environmental Noise Management......................................................... 352.4.2. Directive 2002/49/EC..................................................................... 442.5. Aircraft Noise Modelling................................................................. 452.5.1. USA FAA Integrated Noise Model (INM) ....................................... 452.5.2. UK CAA ANCON ........................................................................... 452.5.3. Australian Transparent Noise Information Package ...................... 462.6. Summary of Aircraft Noise Assessment Methods ....................... 462.6.1. Canada: Noise Exposure Forecast (NEF) ..................................... 472.6.2. Australia: Australian Noise Exposure Forecast (ANEF)................. 482.6.3. USA: Day-Night Average Sound Level (DNL)................................ 492.6.4. USA: Community Noise Equivalent Level (CNEL)......................... 502.6.5. European Union L den and L night ....................................................... 52

2.6.6. United Kingdom L Aeq,16hr and L Aeq,8hr .............................................. 533.0 SECTION 3 – NOISE MODELLING OF AIRCRAFT OPERATIONSAT A ‘TYPICAL’ AIRPORT ......................................................................... 543.1. Introduction ..................................................................................... 543.2. The Noise Metrics to be Further Investigated............................... 543.3. The Hypothetical Airport and its Operations ................................ 543.4. Overview of Utilisation of the Integrated Noise Model................. 593.5. Results of the Computer Modelling............................................... 613.5.1. Canada: Noise Exposure Forecast (NEF) ..................................... 613.5.2. Australia: Australian Noise Exposure Forecast (ANEF)................. 623.5.3. USA: Day-Night Average Sound Level (DNL)................................ 633.5.4. USA: Community Noise Equivalent Level (CNEL)......................... 643.5.5. European Union: L den ..................................................................... 653.5.6. European Union: L night .................................................................... 663.5.7. United Kingdom: L Aeq,16hr ............................................................... 673.5.8. United Kingdom: L Aeq,8hr ................................................................. 683.5.9. Comparison of Residential Planning Criteria in Different Regions. 703.6. Discussion of Results..................................................................... 744.0 SECTION 4 – SUMMARY, CONCLUSIONS AND AREAS FORFURTHER WORK ....................................................................................... 765.0 SECTION 5 – REFERENCES........................................................... 78APPENDICESAppendix 1: Photographs of Examples of Aircraft Used for Noise ModelsAppendix 2: 16 Hour Day Scenario INM Input DataAppendix 3: 15 Hour Day Scenario INM Input DataAppendix 4: Utilisation of Integrated Noise Model SoftwareAppendix 5: Resultant Noise Contours from Modelling Exercise

Methods of Assessment of Aircraft NoiseNigel Burton1.0 SECTION 1 – BACKGROUND AND INTRODUCTIONSince their development, the modern world has rapidly learnt to rely heavilyon motorised vehicles. Coupled with their obvious benefits in terms oftransportation of goods and people come a number of consequentialdisadvantages. Environmental issues, such as noise, continue to gainexposure in the media as the growing population affected by them demand aresponse from those polluting the atmosphere in which they live.With the emphasis being placed upon the polluters to be accountable for theiractions, and authorities such as the European Union requiring all membercountries to develop maps of environmental noise in populated areas,methods for the measurement, prediction and assessment of environmentalnoise issues are coming under increasing scrutiny. The use of specificmethods will therefore require justification and their reliability to bedemonstrated and proven.Both historically and internationally a variety of methods have been adoptedfor the assessment of aircraft noise. The first objective of this project is toexamine a number of the most common methods adopted in the past and atpresent as well as identifying new methods proposed for future use. Thephilosophy behind these methods will be considered and their respectiveadvantages and disadvantages in gauging the problems caused by aircraftnoise examined.The second part of the project will involve the use of aircraft operations dataat a theoretical airport in order to examine the different results that can bepresented by the use of different noise descriptors. The Integrated NoiseModel (INM) software produced by the Federal Aviation Authority (FAA) inthe United States will be used for this purpose. The results of this modellingexercise will be analysed to determine which methods produce the worstcase and best case scenarios.Section 1 – Background and Introduction 6

Methods of Assessment of Aircraft NoiseNigel BurtonIn order to restrict the scope of this project, the investigation will concentrateon conventional fixed wing civilian aircraft and as such will not focus on theeffects of helicopters, military or supersonic aircraft.Section 1 – Background and Introduction 7

Methods of Assessment of Aircraft NoiseNigel Burton2.0 SECTION 2 – LITERATURE REVIEW AND RESEARCH2.1. Aircraft Noise in the United Kingdom2.1.1. The Wilson Committee ReportOver forty years ago, in July 1963, the British Parliament was presented withthe findings of the Committee for the Problem of Noise in their final report. 1The Committee, often referred to as the Wilson Committee after its chairmanSir Alan Wilson, were appointed in April 1960 “to examine the nature,sources and effects of the problem of noise and to advise what furthermeasures can be taken to mitigate it”. The Committee’s fourteen chapterreport covers a variety of noise and noise related issues and includes achapter dedicated to the topic of aircraft noise. This is often cited as the firstmajor published work on the subject particularly within the United Kingdom.The report identified that the first major introduction of aircraft operations inthe UK was that of military aircraft during the Second World War. After thewar, the civil aviation industry began to grow from a small base of a handfulof airfields/airports. In the beginning, piston-engined aircraft dominated theskies but as time went on these were replaced by turbo-propeller (turbo-prop)aircraft. Although complaints did occur in the early days, noise appearedonly to be a problem in the close vicinity around airports. This was to changewith the introduction of turbo-jet aircraft in 1958. These aircraft were muchlarger in size than had previously been experienced, thus requiring morepower to get them off the ground. The jet engines also produced acharacteristic noise signature which was unfamiliar to those experienced inthe past. Both of these factors are cited as reasons for the steep rise innoise related complaints.Even at this early date the report recognised that “there is ample evidencethat aircraft noise causes much annoyance. Government Departments,Members of Parliament, local authorities and airfield authorities receivenumerous complaints”. Since the issue of aircraft noise was in its infancy,Section 2 – Literature Review and Research 8

Methods of Assessment of Aircraft NoiseNigel Burtonthe committee held a number of its meetings at Heathrow Airport in order toexperience the problem first hand. The committee also requested that twoinvestigations be undertaken; first, “an experiment on the acceptability ofaircraft 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 tobe “the busiest international airport in Great Britain and provides one of themost difficult aircraft noise problems in the world”. The committee reportedthat studies regarding the airport had discovered that most complaints relatedto take off and landing noise, that complaints were greatest near the airportand close to take off and landing routes and that, per 100 movements, heavyjet-engined aircraft produced the most complaints. Whilst most complaintswere from individuals, public figures and bodies such as Members ofParliament and Local Authorities also voiced their concerns. Despite theobvious problem of aircraft noise, it was noted that there was still a highdemand for housing in the areas close to the airport. This was principallyattributed to the opportunities of employment at the airport. As well asaffecting people in their homes, the report recognised that aircraft noise couldimpinge on the communications of those working or studying in the area andcould have detrimental affects on patients and staff in hospitals. The Ministryof Health recognised the problems in hospitals and ordered that newbuildings in badly affected areas would be designed to reduce the noiseexperienced internally with the use of upgraded glazing and mechanicalventilation, etc. One of Her Majesty’s Inspectors of Schools noted that on avisit to a school in the Heathrow area a half hour assembly was interruptedby aircraft noise a total of ten times on the first day of their visit and that onthe second day was abandoned. It is reported that experiments were beingundertaken to improve the sound insulation and that new schools in areaswhere aircraft noise may “seriously affect school activities” should be locatedin quiet areas and arranged and built to provide reasonable protectionagainst noise.Section 2 – Literature Review and Research 9

Methods of Assessment of Aircraft NoiseNigel BurtonIn relation to the legal position of those affected by aircraft noise, it isreported that “Sections 40 and 41 of the Civil Aviation Act, 1949, broadlyprohibit actions for nuisance arising from civil aircraft in flight or onaerodromes”. Due to the restriction on legal action the Minister for Aviationat the time considered “himself under an obligation to take steps to minimisethe nuisance” caused by aircraft noise.A number of methods of reducing the noise problem are discussed includingthe reduction of noise at source, take-off, landing and ground runningprocedures as well as methods of monitoring the noise. Increasing work inresearch and development was being carried out to address the problem ofaircraft noise. It was reported that most jet aircraft that used Heathrow werefitted with suppressors which whilst reducing the noise level increasedrunning costs “since they reduce take off thrust, and increase fuelconsumption, drag and weight”. At the time, most new jets that were cominginto service employed bypass or ducted fan jet engines. These were foundto be 10-12 dB quieter than the conventional jet engines but that littleadditional attenuation could be achieved with the use of suppressors in thesecases. Continuing work into reducing the whine of compressors, the principalcause of annoyance when aircraft came into land, was also carried out.The committee reported that the maximum permissible take off noise levelsof jet-engined aircraft should be no higher than for larger piston-enginedaircraft. This statement proved problematic since piston-engined aircraftvaried in noise level and it was felt to be unfair to use the noisiest of theseaircraft as a benchmark. It was also recognised that the characteristic noiseproduced by jet-engined aircraft should be taken into account. Theseproblems were examined by the Port of New York Authority and research“based upon human judgements of a number of piston-engined and jetenginedaircraft” culminated in the creation of a new noise metric, thePerceived Noise Level which was rated in PNdB. The Port of New YorkAuthority adopted a limit of 112 PNdB (roughly comparable with 98 dBA), afigure which was exceeded by 25 per cent of larger piston engined aircraftstill in operation. Heathrow adopted a slightly lower figure of 110 PNdBSection 2 – Literature Review and Research 10

Methods of Assessment of Aircraft NoiseNigel Burton(equivalent to about 96 dBA). Following the implementation of the limit,aircraft operators were not permitted to introduce scheduled services atHeathrow without indicating that they could ensure that their aircraft wouldnot exceed the limit at predefined “first built-up areas” after take off. Initiallyno scheduled operations were permitted during the night-time period, takenas 23:00-07:00 hr, but delayed aircraft would be permitted to take off only ifthey proved “high compliance” with the 110 PNdB limit. Any aircraft wishingto depart after midnight would need to prove a much lower limit, generally102 PNdB (around 88 dBA). However, from 1 April 1960 a number ofscheduled services were permitted to operate during the night-time periodproviding that compliance with the 102 PNdB limit was proven. TheCommittee reported that airlines could achieve the new limits in a number ofways, most choosing to use full power to achieve a steep climb beforereducing power before reaching the “first main built-up area”. To achievethis, many operators found that they needed to reduce their take off load,often requiring them to carry less fuel and therefore requiring an additionalrefuelling stop elsewhere.The Committee’s report details the methods adopted by Heathrow Airport tomonitor the noise produced by its aircraft operations. Manual monitoring atan area immediately before first main built-up area captured around 90% ofall take offs by jet-engined aircraft whilst a proposed automatic system wascapable of recording 100% of take offs. The results of the monitoring wereanalysed and explanations sought for “serious or persistent non-compliance”with the adopted limits. Instead of banning operators or pilots, the Airportpromoted cooperation with offenders to conform to the limits in future. Thismethodology clearly worked with only 2% of all measured jet aircraftexceeding the limits between January and August 1962. This result wasseen as commendable due to the high level of skill required by pilots in orderto conform to the limits. In August 1961, the Airport adopted a number ofnew take off routes in an attempt to avoid densely populated areas. TheCommittee noted that these efforts would not assist those living close to theAirport or before the first main built-up areas, and that the limits did not applySection 2 – Literature Review and Research 11

Methods of Assessment of Aircraft NoiseNigel Burtonto propeller-engined aircraft many of which made more noise thanjet-engined aircraft.As methods to improve the noise performance of departing aircraft wereimplemented, the Airport received increasing numbers of complaints relatingto jet-engined aircraft on approach. Improvements in this area were seen ascomplex since requiring aircraft to approach at a steeper angle couldjeopardise safety. It was noted that the 3° minimum approach angle wasrarely breeched.An important issue that was addressed was the fact that aircraft in flight didnot pose the only noise problem at and around airports. It was reported thatHeathrow was a major maintenance base where essential ground runningoperations, coupled with their consequential noise, were required to takeplace. A number of methods of reducing this ground running noise werediscussed including keeping ground running to a minimum (particularly duringthe night-time period), the construction of noise screens and earth bunds andthe use of mufflers to attenuate the noise of jet engines. It was noted that atHeathrow Airport most of these methods had been implemented by theAirport at significant cost but that only a small number of complaints werethen received relating to ground running, some of which were understood torelate to aircraft taxiing. In order to achieve further reductions in complaints itwas suggested that aircraft could be towed around the apron instead oftaxiing under their own power. This suggestion was rejected since it was feltthat the reduction in noise “would not counterbalance” the problems causedto the Airport and the operators by such procedures. A valuable point raisedwas that jet-engined aircraft did not require running up in order to reachoperating temperature before take off, where as piston-engined aircraft did.The Committee asked the Ministry of Aviation to poll the opinions of otherinternational airports on the issues of noise. The findings were that mostconsidered noise as a “grave problem” and that the majority of complaintsrelated to jet-engined aircraft, particularly on take off, and that night flightsSection 2 – Literature Review and Research 12

Methods of Assessment of Aircraft NoiseNigel Burtonproduced a “proportionately greater amount of disturbance than day flights”.A variety of different methods were employed by other airports to alleviatethe problems of noise, all of which were already in use at Heathrow. TheCommittee reported that “it proved impossible to make detailed comparisonsbetween the problems at Heathrow and other airports” due to the differencesin circumstances at each airport. It was noted that, although aircraft noisewas unpopular, if too strict a line were imposed upon operators at Heathrowsuch that their profitability dropped significantly, they might move theiroperations to other European airports. The Committee remarked that “asubstantial reduction in air services to Heathrow, which serves London and,indeed, the whole country, would have a grave deleterious effect on thecountry’s economy”.The Committee goes on to discuss the problems with noise that could occurin the future. It recognised that the medium and long range jet-enginedaircraft that operated at the time from Heathrow accounted for a minority ofaircraft movements but that with the advent of smaller, short range jetengined aircraft to replace short range propeller engined aircraft would see asubstantial increase in jet-engined aircraft movements. It was forecast thatthe average of 60 jet-engined aircraft movements per day in 1960 wouldincrease to 260 per day by 1965 and 440 per day by 1970. These increaseswere likely to lead to increases in annoyance and disturbance aroundHeathrow Airport but that similar problems were likely to occur at otherairports such as Ringway (Manchester) and Prestwick in Scotland. Withregard to night-time operations in the future it was reported that pressurefrom airlines to allow jet-engined aircraft operations at night in order tomaximise aircraft usage, thus increasing profitability as well as easingcongestion at Heathrow during the daytime, was influencing decisions onAirport policy. Due to factors such as safety, improvements in landing noisewould necessitate reductions in the noise produced by the aircraft and theirengines. As described earlier in the report, through engine developmentnoise reductions of the order of 10-12 dB were being achieved. However,the Committee warned that if operators decided to use extra power whilstremaining within airport limits, the net reduction experienced on the groundSection 2 – Literature Review and Research 13

Methods of Assessment of Aircraft NoiseNigel Burtonmay be minimal. In addition it was noted that it might take several years forthese new breed of quieter aircraft to completely replace the older, noisieraircraft so the benefits may take some time to come into fruition.In order to allow them to gain a greater insight into the problems associatedwith aircraft noise, the Committee asked for two investigations to be carriedout. 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 HeathrowAirport. Initially an additional experiment to investigate the health effects ofnoise on local residents was also requested. Upon advice from both theMedical Research Council and local doctors that it would be difficult toproduce meaningful results and that no significant effects had beenobserved, the request for this investigation was withdrawn.The “experiment on the level of noise which is acceptable” was carried out bythe National Physical Laboratory at Farnborough in 1961. The Committee’sreport states that “60 people were asked, under different conditions on eachof three days, to make subjective judgements of noises of a number ofdifferent types of aircraft, including jet and propeller-driven machines andhelicopters”. The main conclusions that were drawn were that judgement ofnoisiness related to previous experience of the responder to the source andthat 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 livingwithin a 10 mile radius of the airport”• to assess “the amount of disturbance and annoyance caused to thesepeople”• to discover “whether they considered that any advantage accrued tothem from the presence of the airport”• and “to provide information from which an assessment could be madeof the tolerability of the noise to people living in the area”.Section 2 – Literature Review and Research 14

Methods of Assessment of Aircraft NoiseNigel BurtonNoise measurements were also carried out in the areas inhabited by therespondents in order to draw comparisons with the survey results. Severalconclusions were drawn from the results of this experiment. It was found thatthere was good correlation between historical complaints and the “degree ofannoyance” recorded by the survey. Large variations in responses to aircraftnoise meant that significant changes would be required in the level and/orcharacter in order to provoke a significant change in response. Importantly itwas discovered that there was a link between annoyance and increases ineither noise level or aircraft or the number of aircraft movements. Thisconclusion led to the creation of the Noise and Number Index, the underlyingprinciple of which was that annoyance could be kept constant if aircraft noiselevels increased so long as the number of movements decreased, and viceversa.In addition to these experiments, the Building Research Station, now knownas the Building Research Establishment, carried out an investigation into thepossibilities of improving sound insulation of houses. The results of theinvestigation were that the introduction of double windows and suitablyattenuated mechanical ventilation to conventionally single glazed propertiescould produce an improvement in the reduction of aircraft noise from 20 to40 dB.The Committee reported that between 20,000 and 40,000 people in the areaaround Heathrow were subjected to more noise than they could reasonablybe expected to tolerate and that the problem would not get better, and couldget significantly worse, unless action was taken. Two methods to improve orat least maintain the current situation were suggested; the reduction of noiseproduced by aircraft types or the provision of improved sound insulation tolocal homes. The consequences of each of these suggestions wasdiscussed in some detail and, with regard to the latter, considerations ongrant qualification, sources of finance for improvement works andimplications for new dwelling were presented.Section 2 – Literature Review and Research 15

Methods of Assessment of Aircraft NoiseNigel BurtonOn reflection of the obvious problems that already existed at Heathrow, theCommittee recommended that lessons learnt at this airport should be used atother airports. It was noted that since there were no sparsely populatedareas in the UK, serious consideration would be required for the location ofnew airports or the expansion of existing sites.2.1.2. Second Survey of Aircraft Noise Annoyance Around London(Heathrow) AirportIn 1967, the Board of Trade commissioned a “Second Survey of AircraftNoise Annoyance Around London (Heathrow) Airport” 2 . The brief for thisfollow-up work was “to re-examine and to extend the findings of the 1961survey in order to provide information which would help ministers to makedecisions regarding noise control around airports”. The report of the newsurvey noted that, in general, middle class people were more annoyed byaircraft noise than those of working class and that middle aged and elderlypeople were more annoyed than younger people. It was concluded that theresults of the new survey indicated “no increase in annoyance due to aircraftnoise”. Two explanations were presented for this result; 1) that people hadbecome more familiar with aircraft operations and their resulting noise and 2)that although there had been a significant increase in the number of aircraftoperations taking place, there had only been a slight increase in aircraftloudness. The latter was consolidated by a finding that whilst the degree ofannoyance in relation to loudness had stayed the same as that recorded in1961, there was a marked drop in the level of annoyance in relation to thenumber of aircraft. From this finding it was reported that “This throwsconsiderable doubt on the trade off, in annoyance terms, between noise andnumber as inferred from the ‘Noise & Number Index’”.Similar analysis to that carried out in 1961 was undertaken with the results ofthe new survey and similar results were found. More respondents said thatthey had become used to the noise of aircraft than said they had becomemore sensitive despite the fact that noise levels had increased. The surveyalso found that people who had lived in the area and experienced theSection 2 – Literature Review and Research 16

Methods of Assessment of Aircraft NoiseNigel Burtonincrease in noise level were more critical than people who had recentlymoved into the area.2.1.3. The Noise and Number Index SystemAs discussed earlier, the Noise and Number Index metric was developed asa result of the survey work carried out for the Wilson Committee into thecommunity reaction to Aircraft Noise. It is calculated using Equation 2.1.1 3 :NNI = LPNmax+ 15log10N − 80Equation 2.1.1whereL PnmaxN= Logarithmic average of the highest levels of alloverflights= number of aircraft flightsThe subtraction of 80 within the formula relates to the findings of the socialsurvey carried out for the Committee which indicated that the annoyancefactor was zero at 80 PNdB.NNI contour values of 35, 45 and 55 represented low, moderate and highcommunity annoyance respectively. It is understood that NNI was assessedwith regards to operations between mid June and mid October during thehours of 06:00 and 18:00 hrs only.2.1.4. Changes to the Daytime Index for Aircraft NoiseLittle changed with regards to the assessment of aircraft noise in the UnitedKingdom until the early 1980s when the Noise and Number Index wascoming under increasing criticism. The criticisms included the fact that NNIwas out of date, was not easily comparable with other national systems, wasonly valid for Heathrow for which it was formulated and as such wasSection 2 – Literature Review and Research 17

Methods of Assessment of Aircraft NoiseNigel Burtonunsuitable for new airports, that it ignored any events under 80 PNdB, andthat it made no allowance for the duration of individual events. As a result ofthese and other criticisms, the Department of Transport commissioned theCivil Aviation Authority’s (CAA) Directorate of Research and Analysis(DORA) to “Substantiate the NNI or, if necessary, to devise some betterindex for Aircraft Noise”. As such, DORA carried out the “United KingdomAircraft Noise Index Study (ANIS)” and published their results in January1985 4 . As with the earlier Wilson study, the ANIS carried out both noisemeasurements and a social survey; although in contrast to the work in the1960s, the ANIS examined the effects at a total of five airports (Heathrow,Gatwick, Luton, Manchester and Aberdeen) instead of the effects atHeathrow Airport alone. “Common Noise Exposure Areas” commonly ofaround 1 square km were chosen with noise measurements being carried outat a central site within the area and approximately “80 randomly chosenresidents” being surveyed using a questionnaire based on those originallydevised in the 1960s. A total of 26 such areas were examined with a total of2097 questionnaire responses. The main findings of the ANIS were asfollows:• The Study was successful in “disentangling the effects of aircraft noiselevel and number”• The “Guttman Annoyance Scale” was found to be a good measure ofdisturbance and agreed “well with other scales used in the questionnaire”.• The “Trade-Off” factor of 15 used in the NNI expression was found toplace too much weight on the number of aircraft. It was suggested that “avalue of 9 or 10” would be better.• It was concluded that noise events below the 80 PNdB “cut-off” should beincluded as should evening and night-time movements, although withoutweighting as used in other countries.• 24 hour L Aeq 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”) wasestimated to lower the percentage of response of aircraft noise being “notacceptable” by 25%.Section 2 – Literature Review and Research 18

Methods of Assessment of Aircraft NoiseNigel Burton• There were found to be no significant “airport dependent” responsesbased on the results from the five airports under examination.• Whilst the historical use of NNI was unlikely to have “led to majordistortions in the environmental picture” its continued use would lead toproblems, for example with increasing numbers of modern aircraft beingignored due to their noise level being below the 80 PN dB “cut-off”.• It was suggested that 55 and 70 dB L Aeq,24hr could be used to representthe “onset of community annoyance” and the “point of high disturbance”respectively.The proposed change from NNI to L Aeq,24hr was then put out to publicconsultation, the results of which indicated that whilst the majority (80%) ofthe respondents agreed with the use of an L eq based system, many felt the24 hour averaging time suggested by DORA was inappropriate for theassessment of daytime noise. Following the completion of the consultationprocess, in September 1990, the Department of Transport announced thatthey were to replace the Noise and Number Index (NNI) method adopted inthe mid-sixties with L 5 eq,16hr . Whilst NNI contours had been produced formajor airports for some years, in the future these would be replaced byL Aeq,16hr contours. In order to promote greater understanding of the newsystem, both NNI and L Aeq,16hr contours were produced in tandem for twoyears worth of data. It was found that contour levels for each systemcorresponded as shown in Table 2.1.1 below:L Aeq,16hr (dB)NNI (PNdB)57 3560 4063 4566 5069 5572 60Table 2.1.1: L Aeq,16hr and NNI ComparisonSection 2 – Literature Review and Research 19

Methods of Assessment of Aircraft NoiseNigel BurtonAlso in September 1990, the DORA produced a report entitled “The Use ofL eq as an Aircraft Noise Index” 6 . This report included an analysis of theissues raised in the ANIS consultation as well as detailing how the new L eqindex would be implemented.2.1.5. Planning Policy Guidance Note 24: Planning and NoiseIn September 1994, the then Department of Environment published PPG 24,a Planning Policy Guidance Note related to Planning and Noise 7 . The notestates the following:“Planning policy guidance notes set out the Government’s policies ondifferent aspects of planning. Local authorities must take their content intoaccount in preparing their development plans. They may be material todecisions 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 ofapplications for residential development near to transport and industrialrelated noise sources. The different categories are as defined in Table 2.1.2below.Section 2 – Literature Review and Research 20

Methods of Assessment of Aircraft NoiseNigel BurtonNECABCDNoise need not be considered as a determining factor in grantingplanning permission, although the noise level at the high end of thecategory should not be regarded as desirableNoise should be taken into account when determining planningapplications and, where appropriate, conditions imposed to ensure anadequate level of protection against noise.Planning permission should not normally be granted. Where it isconsidered that permission should be given, for example because thereare not alternative quieter sites available, conditions should be imposedto ensure a commensurate level of protection against noise.Planning permission should normally be refused.Table 2.1.2: Definitions of PPG 24 Noise Exposure CategoriesPPG 24 provides recommended noise exposure categories for new dwellingsnear existing noise sources. The noise levels with regards to aircraft noiseare reproduced in Table 2.1.3 below.NOISE LEVELS CORRESPONDING TO THE NOISE EXPOSURECATEGORIES FOR NEW DWELLINGS L Aeq,T dBNOISE EXPOSURE CATEGORYNoise Source A B C DAir Traffic07.00 – 23.0023.00 – 07.0066Table 2.1.3: PPG 24 Recommended NECs w.r.t. Air TrafficAdditional guidance is also provided with regards to night-time noise eventsas follows:“Night-time noise levels (23.00-07.00): sites where individual noise eventsregularly exceed 82 dB LAmax (S time weighting) several times in any hourSection 2 – Literature Review and Research 21

Methods of Assessment of Aircraft NoiseNigel Burtonshould be treated as being in NEC C, regardless of the L Aeq,8h (except wherethe L Aeq,8h already puts the site in NEC D).”2.1.6. White Paper – The Future of Air TransportIn December 2003, the Department of Transport published a white paperentitled “The Future of Air Transport” 8 . The white paper states theGovernment’s position with regards to “the development of airport capacity inthe United Kingdom over the next 30 years”. Prior to the publication of thewhite paper, seven regional consultation documents were published fromwhich 500,000 responses were received. Just as air travel from and withinthe UK has increased to 500% of what it was 30 years ago, it is widelyaccepted that air travel is likely to increase in the future. Although aircrafttoday are significantly quieter than the early jets in the 1960’s, the predictedfuture growth in air traffic could easily exceed the noise reduction techniquesintroduced thus leading to an increase in noise levels. Whilst theGovernment encourages the obvious economic benefits such as employmentand exportation that air travel brings, it recognises that these should bebalanced with the consequential environmental impacts that result. Withregards to noise, the Government have set out an aim “to limit and, wherepossible, reduce the number of people significantly affected by aircraft noise”.One of the practical suggestions offered to assist in achieving this aim is toplace “limits on the size of the area around major airports affected bysignificant noise level”.The Government also intends implementing EU Directive 2002/49/EC. Thisdirective “requires periodic noise mapping at many airports from 2007 toidentify day and night noise problems and, from 2008, action plans to dealwith 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 Governmentsets out its three tiered approach to noise impacts;Section 2 – Literature Review and Research 22

Methods of Assessment of Aircraft NoiseNigel Burton1. to control the scale of impacts2. to mitigate remaining impacts3. to compensate for those impacts which cannot be mitigatedIt is suggested that a percentage of the “large economic benefits provided byairport development” should go towards the mitigation of the development’simpact in the local area. Whilst voluntary schemes, such as acousticinsulation grant schemes, are encouraged the Government has drawn up a“benchmark for mitigating aircraft noise” which should be adopted by thelarger UK airports (defined as those operating in excess of 50,000movements a year).With “immediate effect”, the Government expects such airports to offerhouseholds exposed to high aircraft noise levels (defined as “69 dBA L eq ormore”) financial assistance with regards to relocation. It also expects theoffer of acoustic insulation in areas of medium to high aircraft noise levels(defined as “63 dBA L eq or more”) not only to residential properties but also toother noise sensitive buildings, for example schools and hospitals. In orderto determine where such measures will be required, airports where noisecontouring programmes are not currently used are encouraged to do so in aneffort to verify the “current noise levels”. In instances where acousticinsulation “cannot provide an appropriate or cost-effective solution”, airportsare expected to provide alternative assistance. Examples of suchalternatives include provision of quiet rooms for reading or music,environmental grants and funding for school trips away from the noisyenvironment.The document also states what is expected of these larger airports followingfuture airport growth. In areas exposed to in excess of 69 dBA L eq whichhave also been subject a “large increase in noise” (defined as 3 dBA L eq ormore), airports should offer to purchase properties. Acoustic insulationshould be offered in areas exposed to 63 dBA L eq or above which have alsosuffered a large increase in noise, as defined above.Section 2 – Literature Review and Research 23

Methods of Assessment of Aircraft NoiseNigel BurtonThe white paper indicates the use of 2002 noise contours as the base yearfor the assessment of impact of future growth at these larger airports and thatfurther contours should be produced at a minimum of five yearly intervals.Airports which are not currently considered “large” should use the year whenthe first operate in excess of 50,000 movements as their base year, withfurther contours being produced at a minimum of five yearly intervals.2.1.7. Brief History of the Development of Heathrow AirportVarious sources present similar accounts of the origins of HeathrowAirport 9,10,11,12,13 . It is reported that the airport was originally known as theGreat Western Aerodrome and was owned by the Fairey Company. Theaerodrome was mainly used for test flights with the vast majority ofcommercial flights operating from the nearby Heston and Hanworth Airfields.It is reported that the aerodrome was requisitioned by the Air Ministry for useby the RAF in 1944 but that no military activities ever took place before it wastransferred to the Ministry of Civil Aviation on 1 January 1946. HeathrowAirport was formally opened on 31 May 1946 with an army surplus tentoperating 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 thatthe first terminal building, now known as Terminal 2, was finished. This wasfollowed by the construction of “Oceanic” terminal (Now Terminal 3) andTerminal 1, opened in 1968. The popularity of the Airport led to the openingof a further terminal, Terminal 4, in 1986.The modern day Heathrow Airport is a far cry from its modest beginnings. In1946, 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 morethan in 1946, to 170 destinations with services being provided by 90 airlinesto 64,000,000 passengers.Amidst much controversy and fervent objection on 20 November 2001, aftera public enquiry lasting 3 years 10 months, the government grantedpermission for the construction of a fifth terminal at Heathrow Airport.Section 2 – Literature Review and Research 24

Methods of Assessment of Aircraft NoiseNigel BurtonTerminal 5 has been designed to cope with a further 30,000,000 passengersusing the Airport each year.2.2. Aircraft Noise in the United States of America and Canada2.2.1. The United States of AmericaDue to the state government system operated within the United States ofAmerica there are a number of different noise assessment systems andcriteria that have been adopted across the country. This said, the bodyultimately responsible for the control and management of aircraft and airportsthroughout the USA is the Federal Aviation Administration (FAA). Part 150 ofthe Federation Aviation Regulations (FAR) “Airport Noise CompatibilityPlanning” sets out standards by which airports must report the noiseexposure produced by their operations and methods by which to “minimisenoise-related land use incompatibilities” 14 . Research by this Author indicatesthat there are two major noise metrics accepted under the currentregulations; the Day-Night Average Sound Level and the Community NoiseEquivalent Level.The Day-Night Average Sound Level (DNL), often referred to as L DN , is, inessence, the average noise level for a 24 hour period with the eventsoccurring during the night-time period of 22:00 to 07:00 hrs being given anincreased weighting. The imposed night-time weighting is justified by the“added intrusiveness of night-time noise events attributable to the fact thatcommunity background noise levels typically decrease at night” 14 . Themajority of federal agencies dealing with noise have formally adopted DNL asa metric for assessing noise exposure with the Federal InteragencyCommittee on Noise (FICON) stating in 1992 that “There are no newdescriptors or metrics of sufficient scientific standing to substitute for thepresent DNL cumulative noise exposure metric” 15 . Although DNL can bemeasured the procedure is time consuming. As such, the majority of airportnoise studies rely heavily on computer modelled DNL contours. Part 150requires that the DNL contour values of 65, 70 and 75 dB be produced.Section 2 – Literature Review and Research 25

Methods of Assessment of Aircraft NoiseNigel BurtonThe Community Noise Equivalent Level (CNEL), often referred to as L DEN ,follows a similar rationale to the DNL but also includes an increasedweighting 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 ofcumulative noise exposure within the region. The contour levels to beproduced for CNEL are understood to be similar to those required by theDNL since the two metrics are considered to be interchangeable.Results from 18 surveys carried out worldwide indicated that DNL/CNELlevels as low as 55 related to around 5 percent of people becoming highlyannoyed 16 . It was noted that the percentage of highly annoyed people rosesharply above around DNL/CNEL 65.It is understood that other metrics such as the Noise Exposure Forecastsystem and the Composite Noise Rating system have also been used for theassessment of aircraft noise within the United States but that their use is nowgenerally redundant.2.2.2. CanadaIn order to obtain information relating to the assessment of aircraft noise inCanada, this Author contacted Mr Tom Lowrey of Transport Canada 17 .According to Mr Lowrey the Noise Exposure Forecast (NEF) system hasbeen used in Canada since the early 1970s. The relevant publication in thiscase is TP 1247E – Land Use in the Vicinity of Airports, Part IV of which isentitled “Aircraft Noise” 18 . The NEF system, originally developed in theUnited States of America, is based on the Effective Perceived Noise Levelmetric (EPNL). This metric, along with its corresponding criteria as adoptedin Canada, is described in more detail in Section 2.6.1.Section 2 – Literature Review and Research 26

Methods of Assessment of Aircraft NoiseNigel BurtonMr Lowrey also explained that Transport Canada operate their own aircraftnoise modelling software which, under review, “compared favourably, withinapproximately 5% or better, with major systems in use throughout the world”.2.3. Aircraft Noise in AustraliaSince 1982, the Australian government has used the Australian NoiseExposure Forecast (ANEF) system as their metric of choice for theassessment of aircraft noise. The ANEF system, which is based on theNoise Exposure Forecast (NEF) system developed in the United States ofAmerica in the late 1960’s, was developed following an investigation of theimpact of aircraft noise on residential communities in Australia carried out bythe National Acoustic Laboratories (NAL) in 1979 19 . The ANEF system isdiscussed in more detail in Section 2.6.2.In 1994, Sydney Kingsford-Smith Airport opened its third runway. Followingthe opening, residents in areas predicted not to be affected during theplanning stage found themselves being disturbed by aircraft noise. Due tothe great magnitude of publicity that surrounded the case a Senate SelectCommittee was formed to examine the issue of aircraft noise in Sydney. Inrelation to the Third Runway project, the Select Committee’s report criticisedthe way in which the future aircraft noise had been depicted in theEnvironmental Impact Statement (EIS) 20 . Whilst the EIS had used theconventional tool of the time for the region, the Australian Noise ExposureForecast (ANEF), many people felt that they had not been provided with afair representation of what, how, and to what extent, the aircraft noise was toaffect them.As a result of the Committee’s findings, the Australian Department ofTransport and Regional Services undertook an investigation of differentmethods of aircraft noise assessment. In March 2000, the Departmentpublished a discussion paper entitled “Expanding Ways to Describe andAssess Aircraft Noise” 21 . The document was produced to “promote debateon the development and use of more transparent approaches to describingSection 2 – Literature Review and Research 27

Methods of Assessment of Aircraft NoiseNigel Burtonand assessing aircraft noise around Australian airports”. The paper makesthe suggestion that in order to allow aircraft noise to be better understood bythe layperson, it should be described in terminology that relates to the mostcommon questions asked by the layperson in connection with aircraft noise.It suggested that members of the public were often interested in answers tothe 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 ANEFcontours on their own does not give explicit answers to any of them. Thepaper was careful not to reject or dismiss the use of ANEF system butinstead proposed that supplementing its use with other metrics shouldimprove understanding of the impacts surrounding the introduction of orproposed 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 Numbers2. Respite3. The N704. The Person-Events Index and The Average Individual ExposureSection 2 – Literature Review and Research 28

Methods of Assessment of Aircraft NoiseNigel BurtonFlight Paths and Movement NumbersWhen looking at buying homes near airports people often examine flight pathdata in order to assist them with their task. It is assumed that if a property isunder a flight path it will be noisy, and if not it will be quiet. Whilst this is anoversimplification of the situation the basic principle is correct. The level ofair traffic utilising the different flight paths is also a major factor that will affectthe 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 offlight path movement charts has been developed.Unlike traditional flight path plans which show individual thin lines for eachpath, those shown on the new charts get wider as they get further away fromthe airport. This displays the natural dispersion of aircraft in flight anddispelling the myth of aircraft flying along “railway tracks in the sky”. Inaddition, the charts include: data for each path on the average number ofdaily movements; the number of jet aircraft utilising the route as a percentageof the total number of jet aircraft movements; the daily range (i.e. min andmax) of aircraft movements along the route; and the percentage of days withno movements.The discussion paper states that these types of charts have been used atSydney Airport since 1998 and have been well received. However,limitations of this method have been identified. These include the fact thatthere is no dissemination between small and large aircraft (all are taken to besimilar) and that the wider paths, showing more dispersion, are often wronglyinterpreted as noisier in comparison with narrower paths where flights areconcentrated over a smaller area.RespiteA significant problem with the use of the L Aeq metric or similar system is thatthey assume that annoyance levels will remain the same if the number ofaircraft operations are doubled so long as the individual aircraft noise levelsSection 2 – Literature Review and Research 29

Methods of Assessment of Aircraft NoiseNigel Burtonare reduced by 3 dB. Whilst a reduction of 3 dB for an individual aircraftevent may only just be noticeable, a doubling of movements is likely to havea far greater effect.With this in mind, and as the number of aircraft movements increases, asthey have in recent years and are predicted to in the future, the layperson isinterested to know when they will have a break from the noise, hence theidea of specifying respite. In Australia, “extensive debate” took place overthe most effective way to define respite. Examination was made of thethreshold noise level and the time period over which no aircraft events occur.Due to difficulties with definitions and computation the use of a specificthreshold noise level was not feasible. Instead, flight path usage was utilisedfor the purposes of respite description. This still left the issue of what timeperiod should be used. The approach adopted by Sydney Kingsford-SmithAirport for their monthly monitoring report was to calculate the number ofwhole clock hours when no movements occurred on a given flight path. Thisfigure is then presented as a percentage of the total number of clock hours inthe period under examination. The example offered is that “if there were nomovements on a particular flight path during 50 clock hours in a 100 hourclock period then it would be reported as ‘Respite Hours 50%’”. A clock houris, 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-timeperiod is not a prominent issue at Sydney Airport due to it’s strictly enforcedcurfew hence the lack of information relating to 23:00-06:00 hrs.Consideration has been given to producing a single figure for respite at aparticular location by weighting and then combining the results for the variousSection 2 – Literature Review and Research 30

Methods of Assessment of Aircraft NoiseNigel Burtontime periods. To date, this has been avoided since, it is felt, it would reducethe clarity of the information.Respite charts have not been as well received as the flight path andmovement charts described earlier. One criticism of the technique and itsuse in Sydney has been that certain areas may be close to more than oneflight path. This would mean that whilst no aircraft might be operating on thenearest route to a particular location, it might still be affected by noise fromactivity on other routes. This problem is likely to be particularly prevalent atlocations close to an airport. No obvious solution has been found for thisproblem though it is noted that “for most parts of Sydney the charts give avery 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 clockhours can lead to an underestimation of respite. The example given is that “ifthere were one movement at 12:05pm and one movement at 1:55pm norespite would be recorded for that two hour period. This would be despite thefact that for virtually all that period (110 minutes) there were no movements”.Based on the predicted increase in aircraft movements in the future, theissue of respite from aircraft is one that will not go away and thereforerequires further investigation and research.The N70Due to some of the apparent shortcomings of the ANEF system, discussionstook place in Sydney between the airport and the various local communitiesto find the best way to provide an easily comprehensible method to describeactual aircraft noise levels. After trialling the use of SEL footprints forindividual aircraft it was found that to provide such information for all aircrafttypes, on all routes, and including information on the number of movementswas 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 aircraftSection 2 – Literature Review and Research 31

Methods of Assessment of Aircraft NoiseNigel Burtonmovements 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 nomeans a new concept but has been around for over 20 years and wasexamined in a study carried out by the National Acoustic Laboratory inAustralia in 1982 22 .The Australian Standard AS2021 23 specifies the single event level of 60dB(A) as “the indoor design sound level for normal domestic areas indwellings” since this is the level at which “a noise event is likely to interferewith conversation or with listening to the radio or the television”. Given that ahouse with partially open windows provides around 10 dB(A) attenuation ofexternal noise sources leads us to the rationale behind the choice of 70dB(A) SEL for as the noise threshold, and hence the N70.The discussion paper states that the N70 contours can and have beenproduced with the aid of the United States Federal Aviation Administration’sIntegrated Noise Model (INM). Since the INM package does not offer thecalculation of N70 contours as a standard output metric, additionalcomputation is required. The Department of Transport and RegionalServices in Australia has now produced software for the creation of N70 andother noise contours. This software is discussed in more detail in a latersection.In order to deal with ‘sensitive times’, as described earlier, it is seenappropriate to produce N70 contours for these specific time periods. It isimportant to understand that ‘number above’ contours for different noiselevels can also be produced. An example of their use is the N60 contour ofwhich a number were produced for the 22:00 to 06:00 hrs period in theEnvironmental Impact Statement for the second Sydney airport. The level of60 dB(A) SEL chosen in that case corresponds to “the sleep disturbancelevel of 50 dB(A) specified in AS2021” again allowing for 10 dB attenuationby the fabric of the building.Section 2 – Literature Review and Research 32

Methods of Assessment of Aircraft NoiseNigel BurtonThe discussion paper reports various methods of producing combined N70contours such as by applying different weightings to events, which take placeduring sensitive times.In practice, N70 contours have been produced to as low as “10 events perday exceeding 70 dB(A) level”. It is noted, however, that whilst this covers asignificantly larger area than would be cover for a similar 20 ANEF contour,contours produced at such a low level using the INM raise “significantquestions about the accuracy of the information”.Due to its arithmetic nature, the N70 is easier for the layperson to understandthan other, logarithmic indicators. The example given is that “all other thingsbeing equal, if the number of movements over an area doubles the N70doubles”. The N70 can also be used to present the results of actualmeasured 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 doesnot differentiate between aircraft events of 70 dB(A) and those of higherlevels such as, for example, 90 dB(A). It is suggested that this could beovercome 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 ExposureA useful way to assess the impact of aircraft noise is to determine thenumber of people that will be affected by it. At many airports noisepreferential routing is used to divert aircraft away from greatly populatedareas. Whilst assessing the total number of people affected is important,decisions sometimes have to be made as to whether it is worse for a smallnumber of people to be exposed to high noise levels or if it is worse for alarge number of people to be exposed to lower noise levels. This questioncreates a problem for decision makers, many of whom will not be expertsSection 2 – Literature Review and Research 33

Methods of Assessment of Aircraft NoiseNigel Burtonwith regards to noise, since they may not understand the differencesbetween the two scenarios sufficiently to make considered judgements.To assist non-experts with interpretation of this type of information, theDepartment of Transport and Regional Services in Australia has devised thePerson-Events Index (PEI). The discussion paper states that “the index isnot intended to replace existing noise indicators but to supplement them”.The PEI is calculated using Equation 2.3.1 below:PEI( x) = ∑ PNNEquation 2.3.1“where x = The single event threshold noise level expressed in dB(A)P N = The number on persons exposed to N events > x dB(A)The PEI is summed over the range between N min (a defined cut-off level) andN max (the highest number of noise events louder than x dB(A) persons areexposed to during the period of interest)”.An example given in the discussion paper is that if a single departure by oneaircraft 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 tookplace, similar to the first event, then the total PEI(70) for both eventscombined would be 40,000. A more detailed example of the use of PEI ispresented in the discussion paper examining different operating scenarios atSydney Airport.The information provided by the PEI is not comprehensive and requiresfurther 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 amillion events of 70 dB(A) or more, or it could mean that a million people areexposed to one event of 70 dB(A) or more, or any other situation betweenSection 2 – Literature Review and Research 34

Methods of Assessment of Aircraft NoiseNigel Burtonthese two extremes. This requirement for further clarification has led to thecreation of average individual exposure (AIE) which is calculated usingEquation 2.3.2 below:PEIAIE =Total Exposed PopulationEquation 2.3.2As with the PEI, the AIE is based on a defined minimum cut-off level of xnumber of events per day.Like the N70 described earlier, the PEI and AIE are both arithmetic andtherefore show “differences between scenarios much more starkly thanlogarithmic indices which dampen any difference”.The discussion paper notes that the PEI is useful “for computing partial noiseloads” and can produce meaningful results even one or a small number ofmovements. It can also be used to compare results at different airports. It isadvised that the AIE should not generally be used for this purpose but that itis useful “when comparing different operating scenarios at a particularairport”.2.4. Aircraft Noise in the European UnionDifferent countries in the European Union rate aircraft noise indicesdifferently, below are the methods currently adopted in a number of countriesor regions.2.4.1. An Inventory of Current European Methodologies and Procedures forEnvironmental Noise ManagementIn preparation for the European Commission’s Directive on the Assessmentand Management of Environmental Noise, and in particular the requirementSection 2 – Literature Review and Research 35

Methods of Assessment of Aircraft NoiseNigel Burtonfor Noise Mapping, the European Environment Agency commissioned Ian HFlindell and Andrew R McKenzie to produce “An Inventory of CurrentEuropean Methodologies and Procedures for Environmental Noise” 24 . Theirfindings, which were published in June 2000 included methods ofassessment of aircraft noise in 17 member states. These methods,excluding those adopted in the UK as discussed earlier, are summarisedbelow:AustriaDaytime (06:00-22:00) L Aeq,16hr Contours 60, 65 and 70 dB.Night-time (22:00-06:00) L Aeq,8hr Contours 50, 55 and 60 dB.Noise Limits based on L DN (maximum of day and night values, with 10 dBadded to the night-time values).Planning guidance as indicated in Table 2.4.1 below:L DN /L Amax New BuildingsAgricultural, military and airport>75/105 buildings only. No newresidential zones.Residential buildings in existingzone and commercial buildings to>65/-have required sound insulation.No new residential zones.Residential buildings in existing>60/-zone. No new residential zones.Noise sensitive buildings only in>55/- case of overriding need withrequired sound insulationExisting BuildingsResidential and noise sensitivebuildings (schools, hospitals,nursing homes) to have requiredsound insulation.Noise sensitive buildings(schools, hospitals, nursinghomes) to have required soundinsulation.Table 2.4.1: Austrian Planning Guidance relating to Aircraft NoiseIt was noted that a revised version of the reference, due for editing in 2000,would include L den as a “specified indicator”.Section 2 – Literature Review and Research 36

Methods of Assessment of Aircraft NoiseNigel BurtonBelgium – FlandersL DN with a 10 dB weighting for night-time period (22:00-07:00). “Zones areestablished corresponding to L DN values of 55-60, 60-65, 65-70, 70-75 withthe percentages of highly annoyed people in each zone calculated from%HA=0.0684*(L DN -42)”.Belgium – WallonieL dn - similar to L Aeq with 10 dB night-time weighting (22:00-07:00). Noiselevels divided into planning zones:“Zone A – L dn >70Reserved only for activities linked with the functioning of the airport. Theadministration will propose to owners of dwellings in this zone to buy theirhouse. No new construction is admitted. No financial aid is given foracoustic insulation.Zone B – L dn 65-70In this zone, a financial aid will be proposed for the acoustic insulation ofexisting dwellings. No new dwellings should be allowed in this zone.Economic activities are admitted.Zone C – L dn 60-65Financial aid will be proposed for acoustic insulation of existing dwellings.New dwellings could be allowed, but in a very restricted way, with specificacoustic conditions.Zone D – L dn 55-60Financial aids will occur, but not for offices, sport centres and shops.New dwellings construction will also be restricted.”Belgium – BrusselsL evt – “Sound Exposure Level (SEL) for any individual aircraft eventL Sp avion – “L Aeq from all aircraft events, corrected for the effects of otherbackground noise sources”Divided into zones as indicated in Table 2.4.2 below:Section 2 – Literature Review and Research 37

Methods of Assessment of Aircraft NoiseNigel BurtonZones L evt L Sp avionDaytime(07:00-23:00)Night-time(23:00-07:00)Daytime(07:00-23:00)Night-time(23:00-07:00)0 80 70 55 451 90 80 60 502 100 90 65 55Table 2.4.2: Brussels Planning Guidance relating to Aircraft NoiseDenmarkL den – peak three months, 5 dB weighting for evening, 10 dB weighting fornight-time. The guideline planning limits are presented in Table 2.4.3 below:Area Smaller Airfield Airport or Military AirfieldSummer Residential,Camping45 50Hospital, School 45-50 55Residential 45-50 55Hotel, Office 60 60Rural 50 60Table 2.4.3: Danish Planning Guidance relating to Aircraft NoiseL Amax night-time limit: 70 dB(A) and 80 dB(A) for smaller airfields and airportsand military airfields respectively. State subsidised sound insulation fordwellings exposed to above 65 dB L Aeq .FinlandAll sources treated similarly. L Aeq,d Daytime (07:00-22:00) and L Aeq,n Nighttime(22:00-07:00) guidelines are presented in Table 2.4.4 as follows:Section 2 – Literature Review and Research 38

Methods of Assessment of Aircraft NoiseNigel BurtonDescription L Aeq,d L Aeq,nResidential Areas 55 50Recreation Areas in Conglomerations and Areas in theirProximity55 50Areas Serving Nursing or Educational Institutions 55 50New Residential and Recreation Areas and Areas ServingNursing or Educational Institutions55 45Holiday Settlements (camping site etc). 45 40Table 2.4.4: Finnish Planning Guidance relating to Aircraft NoiseFranceAssessed using Equation 2.4.1 presented below:IEquation 2.4.1whereL i = Noise from each operation in PNdBmaxg i = 1 for operations 06:00-22:00 and 10 for operations 22:00-06:00∑0.1Li= 10log( 10 ) − 32pg iZones, and their respective maximum permitted levels are presented in Table2.4.5 below:Section 2 – Literature Review and Research 39

Methods of Assessment of Aircraft NoiseNigel BurtonZone I p Permitted DevelopmentA >=96Residences and buildings required for aeronautical activitiesand public amenities vital for existing populationsB 89-96Residences required for individual, commercial andagricultural activitiesC 84-89Individual non-estate housing located in already developedsectors, refurbishing operations for districts and existinghomes provided population of noise exposed population notsignification increasedD

Methods of Assessment of Aircraft NoiseNigel BurtonZone L Aeq(4) Permitted Development1 >75No new dwellings, support of insulation at existing dwellings.No convalescent or retirement homes or schools.2 67-75New dwellings only with improved insulation. Noconvalescent or retirement homes or schools.3 40, NEF30-40 and NEF

Methods of Assessment of Aircraft NoiseNigel BurtonIrelandIt is reported that aircraft noise is assessed in this state using the Noise andNumber Index (NNI) but that no limits were specified. NNI is calculated usingEquation 2.4.5 below:NNI = L + 15logNpn ( av )−Equation 2.4.580Where:L pn(av)= average noise level in PndBmax of all operations exceeding80 PndBmaxN = number of operations during period 0600-2200Italy“L va which is a 21 day, 24 hour L Aeq , with a 10 dB night-time (2300-0600)weighting, averaged over the busiest weeks from each of the three period 1 stOctober to 31 st January, 1 st February to 31 st May, and 1 st June to 30 thSeptember.The limits for land use planning are presented in Table 2.4.7 below:Zone L va Permitted DevelopmentA =75 Only Airport Activities Allowed”Table 2.4.7: Italian Planning Guidance relating to Aircraft NoiseLuxembourgAssessment method believed to be similar to that in Germany i.e. L Aeq(4) .Section 2 – Literature Review and Research 42

Methods of Assessment of Aircraft NoiseNigel BurtonThe NetherlandsAircraft noise assessed using Kosten-units which are calculated usingEquation 2.4.6 below:L /15( 10 ) −157iKe = 20log ∑g iEquation 2.4.6where:L i = Max A-weighted sound level for each operation”g i = 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) or4 (07:00-08:00)“Noise limits which must not be exceeded by existing airports are” presentedin below:Noise LevelPlanning Restriction35Generally No New Residential AreasAllowed>40 Generally No New Dwellings Allowed40-50Insulation of Existing Dwellings to NLR30-3550-55Insulation of Existing Dwellings to NLR35-40Table 2.4.8: Dutch Planning Guidance relating to Aircraft NoiseSection 2 – Literature Review and Research 43

Methods of Assessment of Aircraft NoiseNigel Burton“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 50BKL.”PortugalNo specific method for assessing aircraft noise stated.SpainThere are many regional variations in approach to aircraft noise. Referenceis made to grants being applicable for sound insulation improvements toresidential properties built prior to April 1996 where levels of aircraft noise areabove 65 dB L Aeq,(0700-2300) and/or 55 dB L Aeq,(2300-0700) .SwedenAircraft noise is assessed using L den which is based upon L Aeq withweightings 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 L den , noplanning restrictions apply.2.4.2. Directive 2002/49/ECOn the 25 June 2002, the European Parliament published Directive2002/49/EC “relating to the assessment and management of environmentalnoise” 25 . The aim of the directive is “to define a common approach … toavoid, prevent or reduce on a prioritised basis the harmful effects, includingannoyance, due to exposure to environmental noise”. As well as making therequirement that member states begin the production of strategicenvironmental noise maps by no later than 2007, the directive also attemptsto standardise the way in which noise is reported throughout the EuropeanUnion. In an earlier green paper published by the European Parliament in1997 it was noted that there was a “lack of reliable, comparable dataSection 2 – Literature Review and Research 44

Methods of Assessment of Aircraft NoiseNigel Burtonregarding the situation of various noise sources”. The directive emphasisesthat in order to promote common understanding of noise issues, “data aboutenvironmental noise levels should … be collected, collated and reported inaccordance with comparable criteria”. To this end, the directive dictates thatall member states adopt the L den and L night metrics for the purpose ofreporting environmental noise levels. It is also suggested that in certaincases it would be appropriate to also use L day and L night . These metrics arediscussed in more detail in Section 2.6.5.2.5. Aircraft Noise ModellingIt should be noted that the packages described in this section are merely asample 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 NoiseModel (INM) has been used for the prediction of aircraft noise impact in theproximity of airports since the late 1970s 26 . The software is available forpurchase from the FAA and, now in its sixth full version, is arguably the mostwidely used software for aircraft noise modelling. Since this software is to beused for the modelling section of this project, it will be examined in moredetail later.2.5.2. UK CAA ANCONThe ANCON modelling software is not available for purchase but is insteadowned and operated by the CAA. This is unfortunate since, it is argued bythis Author, it means that any UK residents or organisations who wish tomodel aircraft noise are forced to use another modelling package, such asthe INM, or retain the services of the CAA to use their ANCON model. Inmany cases the latter is likely to be prohibitively expensive. This said, theANCON system is used by the government to produce regular noise contoursfor the main BAA airports in the south-east of Heathrow, Stanstead andSection 2 – Literature Review and Research 45

Methods of Assessment of Aircraft NoiseNigel BurtonGatwick. Other airports such as Manchester also employ the ANCONsystem to produce noise contours for the benefit of local authorities in theirarea.2.5.3. Australian Transparent Noise Information PackageIn response to the publication of their discussion paper on “Expanding Waysto Describe and Assess Aircraft Noise” 21 , the Australian Department ofTransport and Regional Services produced a package of computer softwareapplications which made it possible for “non-expert users to generate thedescriptors shown in the Discussion Paper” 27 such as Flight Path MovementCharts, Respite Charts and N70 Contours. The software can alsoincorporate data produced within the INM software.In an attempt to encourage people to use the software it has been availableas freeware and can be obtained from the department. Like other modellingpackages the software can be used to carry out ‘what if’ assessmentstherefore allowing any user to analyse the effects of possible operationalchanges 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 authorityundertaking to improve communication of aircraft noise issues tonon-experts. This kind of approach is likely to reduce the feelings ofresentment often felt towards conventional methods of presenting aircraftnoise due to their complicated nature and subsequent inaccessibility to thelayperson.2.6. Summary of Aircraft Noise Assessment MethodsThe following noise metrics, and their associated criteria levels, have beenselected for use in the next section of this project. The criteria specifiedrelate to those adopted for land use compatibility for residential dwellings inthe particular country or region stated.Section 2 – Literature Review and Research 46

Methods of Assessment of Aircraft NoiseNigel Burton2.6.1. 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 annoyancecaused by aircraft noise and is calculated using Equation 2.6.1 below 28 .NEF = EPNL + 10log( N + 16.7N ) 88 (dB)10 DN−Equation 2.6.1whereEPNL = energy mean value of the EPNLN D = number of daytime flights (07:00-22:00)N N= number of night-time flights (22:00-07:00) – the factor of 16.7 relatesto a 10-1 weighting of night flights as opposed to day flightsIn Canada the land use criteria with regards to residential development is asshown in Table 2.6.1 below:Noise Exposure Forecast Values >40 40-35 35-30

Methods of Assessment of Aircraft NoiseNigel Burtonappropriate note and subject to the limitations indicated therein”. ExplanatoryNote B states that Transport Canada’s recommendation is that “Newresidential construction or development should not be undertaken” in areassubject to between NEF 30 and 35, but offers guidance for those authoritiesthat nevertheless wish to proceed.Transport Canada state that “Annoyance caused by aircraft noise may beginas low as NEF 25”. In essence, residential development will generally beaccepted in areas up to NEF 30 but may require improved acoustic insulationof the building envelope in some cases. For the purposes of this project,NEF 30 has been selected as the level up to which residential developmentis acceptable.2.6.2. Australia: Australian Noise Exposure Forecast (ANEF)The Australian Noise Exposure Forecast was first introduced in Australia in1982 19 . This system of assessment was based on the aircraft NoiseExposure Forecast but with refinements made based on the results of asurvey into the reaction of communities to aircraft noise in Australia. ANEF iscalculated using Equation 2.6.2 below:ANEF = EPNL + 10logEquation 2.6.2( N + 4N ) 88 (dB)10 D N−whereEPNL = energy mean value of the EPNLN D = number of daytime flights (07:00-19:00)N N = number of night-time flights (19:00-07:00)In Australia the land use criteria with regards to residential development is asshown in Table 2.6.2 below 23 :Section 2 – Literature Review and Research 48

Methods of Assessment of Aircraft NoiseNigel BurtonBuilding TypeHouse, home unit,flat, caravan parkANEF zone of siteAcceptable Conditional UnacceptableLess than 20 20 to 25 ANEF Greater than 25ANEF (Note 1) (Note 2)ANEFTable 2.6.2: Extract from Australian Standard AS 2021-1994Note 1 points out that the location of the 20 ANEF contour is difficult toaccurately define “because of variations in aircraft flight paths” and as suchadditional procedures may be followed for “building sites outside but near tothe 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 withresidential or educational uses” and as such noise control features may beappropriate. For the purposes of this project, both the 20 and 25 ANEFcontours will be evaluated.2.6.3. USA: Day-Night Average Sound Level (DNL)The Day-Night Average Sound Level, denoted as DNL or L dn , is an L eq basedsystem which is used to rate the noise present over a 24 hour period. Thenoise levels occurring during the night-time period, which in the United Statesof America is the nine hour period between 22:00 hr and 07:00 hr, are givena 10 dB weighting penalty such that the calculation of the DNL is as shown inEquation 2.6.3 below 29 :DNL = 10log124⎡ ⎛⎢15⎜10⎢⎣⎝Ld10Equation 2.6.3⎞ ⎛⎟ + ⎜910⎠ ⎝Ln+1010⎞⎤⎟⎥⎠⎥⎦whereLd = daytime (07:00 hr – 22:00 hr) L Aeq,15hrLn = night-time (22:00 hr – 07:00 hr) L Aeq,9hrSection 2 – Literature Review and Research 49

Methods of Assessment of Aircraft NoiseNigel BurtonAs noted earlier Part 150 of the Federal Aviation Regulations requires thatthe DNL contours of 65, 70 and 75 by produced. Table 1 of Appendix A ofPart 150 describes compatible land use as a function of YDNL, Yearly Day-Night Average Noise Level. YDNL is defined as the average of daily DNLvalues throughout the year. The land use criteria with regards to residentialdevelopment is as shown below in Table 2.6.3:Yearly Day-Night Average Sound LevelLand Use – Residential Use 8570 75 80 85Residential other than mobile Y N(1) N(1) N N Nhomes and transient lodgingsMobile home park Y N N N N NTransient lodgings Y N(1) N(1) N(1) N NTable 2.6.3: Land Use Compatibility Guidelines from FAR Part 150Where Y means that “Land use and related structures are compatible withoutrestrictions” and N means that “Land use and related structures are notcompatible and should be prohibited”. Note (1) states that “Where thecommunity determines that residential or school uses must be allowed,measures to achieve outdoor to indoor Noise Level Reduction (NLR) of atleast 25 dB and 30 dB should be incorporated into building codes and beconsidered in individual approvals. Normal residential construction can beexpected to provide a NLR of 20 dB, thus, the reduction requirements areoften stated as 5, 10 or 15 dB over the standard construction and normallyassume 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 asL den , 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 asSection 2 – Literature Review and Research 50

Methods of Assessment of Aircraft NoiseNigel Burtonwell as the a 10 dB weighting being placed on all night-time movements, anadditional weighting of multiplying all movements taking place during theevening period (19:00 hr to 22:00) by a factor of three. One method ofcalculating CNEL is as presented in Equation 2.6.4 below:CNEL = SENEL + 10log( N + 3N + 10N ) 49.4 (dB)10 D E N−Equation 2.6.4where N D = Number of flights during the daytime (07:00-19:00 hrs)N E = Number of flights during the evening (19:00-22:00 hrs)N N = Number of flights during the night-time (22:00-07:00 hrs)SENEL = The energy mean value of the single event noise exposureas calculated using Equation 2.6.5 below:SENEL = NL + 10logmax10teaEquation 2.6.5where NL max = The maximum noise level in dB(A)t ea = The effective time duration (in seconds) of the noise level. It isapproximately equal to half of the time during which the event noiselevel is within 10 dB of the maximum.SENEL is similar to SEL but measured for the time interval whilst noise froman aircraft exceeds a predetermined threshold level 14 . In general, theSENEL result will be similar to that of the SEL.Another method of calculating CNEL is the altered version of the DNLformula as presented in Equation 2.6.6 below:Section 2 – Literature Review and Research 51

Methods of Assessment of Aircraft NoiseNigel BurtonCNEL = 10log124⎡ ⎛⎢12⎜10⎢⎣⎝Ld10⎞ ⎛⎟ + ⎜310⎠ ⎝Equation 2.6.6Le+510⎞ ⎛⎟ + ⎜910⎠ ⎝Ln+1010⎞⎤⎟⎥⎠⎥⎦whereLd = daytime (07:00 hr – 19:00 hr) L Aeq,12hrLe = evening (19:00 hr – 22:00 hr) L Aeq,3hrLn = night-time (22:00 hr – 07:00 hr) L Aeq,9hrThe FAA accepts CNEL in place of DNL for studies conducted withinCalifornia since the region has adopted CNEL as its standard for theassessment of cumulative community noise exposures. As such, DNL andCNEL are interchangeable and the land use criteria for residentialdevelopment described in FAR Part 150 and reproduced in Table 2.6.3 arecompatible for both metrics.2.6.5. European Union L den and L nightDirective 2002/49/EC states that the calculation of L den is as presented inEquation 2.6.7 below 25 :Lden= 10lg124⎛⎜12× 10⎜⎝Lday10+ 4 × 10Levening+ 510+ 8 × 10Lnight+ 1010⎞⎟⎟⎠Equation 2.6.7whereL day = “the A-weighted long-term sound level … determinedover all the day periods of a year”L evening = “the A-weighted long-term sound level … determinedover all the evening periods of a year”L night = “the A-weighted long-term sound level … determinedover all the night periods of a year”Section 2 – Literature Review and Research 52

Methods of Assessment of Aircraft NoiseNigel BurtonThe unit is effectively the same as CNEL but differs due to the differentdurations of the day, evening and night-time periods. The European Unionallows for individual member states to “shorten the evening period be one ortwo hours and lengthen the day and/or the night period accordingly”. Sincethe UK currently adopts a 16 hour day and 8 hour night it is likely that thestandard form presented above will be used in this country. The L night is to betaken as defined above.The European Union requires the use of these metrics for the purposes ofassessment and noise mapping but has not set out any specific criteria foracceptable or unacceptable levels for planning use. This said, contours of55, 60, 65, 70 and 75 dB L den are required for the assessment of “theestimated number of people” exposed to such noise levels. For the samepurpose, the contours of 50, 55, 60, 65 and 70 dB L night are required for thenight-time period.2.6.6. United Kingdom L Aeq,16hr and L Aeq,8hrAs described in Section 2.1.5, Planning Policy Guidance Note 24 states theGovernment’s policy on planning with regards to noise 7 . The planningcriteria are detailed in that section.Section 2 – Literature Review and Research 53

Methods of Assessment of Aircraft NoiseNigel Burton3.0 SECTION 3 – NOISE MODELLING OF AIRCRAFT OPERATIONSAT A ‘TYPICAL’ AIRPORT3.1. IntroductionFor this section of the project, the noise assessment methods discussed inSection 2.6 have been identified for further examination. The examinationwill involve modelling the different metrics for the operations at ahypothetical, yet realistic, airport. Following the modelling process the resultsfor each metric will be compared with each other and with their respectivecriteria to determine which of them operate the most stringent and least strictstandards.3.2. The Noise Metrics to be Further InvestigatedA total of 8 noise metrics have been selected for further investigation. They,along with their respective country or region of use in brackets, are asfollows:• Noise Exposure Forecast, NEF (Canada)• Australian Noise Exposure Forecast, ANEF (Australia)• Day-Night Average Sound Level, DNL (USA)• Community Noise Equivalent Level, CNEL (USA)• L den (European Union)• L night (European Union)• L Aeq,16hr (United Kingdom)• L Aeq,8hr (United Kingdom)3.3. The Hypothetical Airport and its OperationsThe hypothetical airport operates a single runway which is 3050m in length.The aircraft operations at this airport are based closely on movement datafrom an existing European regional airport though the data has beenSection 3 – Noise Modelling of Operations at a ‘Typical’ Airport 54

Methods of Assessment of Aircraft NoiseNigel Burtonsomewhat simplified for the purposes of this assessment. The runwaydesignations at the airport are 09 and 27, due east and due westrespectively. Each of the two runway designations has two departure flightpaths, or routes, and one arrival path. One departure route on each runwaydesignation turns towards the north, whilst the other turns towards the south.The arrival paths on each runway designation are straight in and thereforefollow the extended centreline of the runway. Figure 3.3.1 below shows thebasic layout of the runway at the airport and its departure and arrival routes.27N09N09A27A27S09SFigure 3.3.1: Basic Layout of Runway and Departure and Arrival RoutesMovement data for a total of eleven different aircraft types has beenproduced. The total daily movements for each aircraft type are shown inTable 3.3.1 below:Section 3 – Noise Modelling of Operations at a ‘Typical’ Airport 55

Methods of Assessment of Aircraft NoiseNigel BurtonAircraft Type Class Sector Length Total MovementsEmbraer 145 1 1 66Dash 8 1 1 66Airbus A319 2 2 109Airbus A320 2 3 109Boeing 737-700 2 3 109Boeing 737-800 2 2 109Airbus A310 3 4 11.2Boeing 757 3 4 22.4Boeing 767 3 6 22.4Airbus A300 4 5 48Airbus A330 4 6 48Total Number of Movements by All Aircraft 720Table 3.3.1: Total Number of Daily Movements by Aircraft TypeThe reason that some aircraft types in the table have either an odd numberor non-whole number of movements is that these figures relate to data for anaverage day. Some aircraft will not fly everyday and hence the apparentlyunusual input data. The class of the aircraft type relates to its size, weightand capacity with the Airbus A300 and Airbus A330 being the largest aircrafttypes to be included in this assessment. The sector length relates to thedistance that the aircraft type is going to fly. In this case, the sector lengthsrelate to the profile stage number utilised by the INM, where 1 is 0 to 500nautical miles (nmi), 2 is 500 to 1000 nmi, 3 is 1000 to 1500 nmi and 4 is1500 to 2500 nmi. Photographs of examples of all of the aircraft types areshown in Appendix 1.The data in Table 3.3.1 was then divided in departures and arrivals by aircrafttype using a simple 50%/50% split, since all aircraft arriving must depart.The departure and arrivals for each aircraft type were then split by runwaydesignation. In common with many UK airport, a split of 70%/30% in favourof the western (27) routes was used. Finally, the departures on each runwaydesignation and for each aircraft type were split into those going north andSection 3 – Noise Modelling of Operations at a ‘Typical’ Airport 56

Methods of Assessment of Aircraft NoiseNigel Burtonthose going south. For the purposes of this assessment it has beenassumed that 80% of all departures turn towards the south whilst theremaining 20% turn towards the north. These routings are not dissimilar fromthose used at several UK airports due to large proportion of traffic headingsouth towards mainland Europe. The results of these computations areshown in Table 3.3.2 below:Aircraft Type Runway 09 (Due East) Runway 27 (Due West)Arrival Departure Arrival Departure09A 09N 09S 27A 27N 27SEmbraer 145 9.9000 1.9800 7.9200 23.1000 4.6200 18.4800Dash 8 9.9000 1.9800 7.9200 23.1000 4.6200 18.4800Airbus A319 16.3500 3.2700 13.0800 38.1500 7.6300 30.5200Airbus A320 16.3500 3.2700 13.0800 38.1500 7.6300 30.5200Boeing 737-700 16.3500 3.2700 13.0800 38.1500 7.6300 30.5200Boeing 737-800 16.3500 3.2700 13.0800 38.1500 7.6300 30.5200Airbus A310 1.6800 0.3360 1.3440 3.9200 0.7840 3.1360Boeing 757 3.3600 0.6720 2.6880 7.8400 1.5680 6.2720Boeing 767 3.3600 0.6720 2.6880 7.8400 1.5680 6.2720Airbus A300 7.2000 1.4400 5.7600 16.8000 3.3600 13.4400Airbus A330 7.2000 1.4400 5.7600 16.8000 3.3600 13.4400Sub-total: routes 108.0 21.6 86.4 252.0 50.4 201.6Sub-total: runway 216 504TOTAL 720Table 3.3.2: Daily Movements split by Runway, Movement Type and RouteNote: The reason for the large number of decimal places in the movementdata 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 totalnumber of daily movements needed to be split into the daytime, evening andnight-time periods. This creates a problem since not all of the metrics usesimilar durations for these periods. For example, the L Aeq,16hr system adoptedSection 3 – Noise Modelling of Operations at a ‘Typical’ Airport 57

Methods of Assessment of Aircraft NoiseNigel Burtonin the United Kingdom assumes the daytime period to operate between07:00 hr and 23:00 hr whilst the US based Day-Night Average Sound LevelSystem assumes a daytime period between 07:00 hr and 22:00 hr, 1 hourshorter than the UK system. Therefore, for the purposes of this project, itwas decided to model each metric using its own preferred time periods. Thishas meant separating the metrics into two groups; those which operate a15 hr day and those which operate a 16 hr day as shown in Table 3.3.3below.Daytime Period Reference15 Hour Day • Canadian NEF• Australian NEF• USA DNL• USA CNEL16 Hour Day • UK L Aeq,16hr• UK L Aeq,8hr• EU L den• EU L nightTable 3.3.3: Groupings for Computer ModellingAs a result of the two groups, it was necessary to create two separatemodels, one for each scenario. The daily movement data split by runway,movement type and route were again split, but this time by daytime, eveningand night-time movements. For simplicity it has been assumed that, for the16 hr daytime scenario, 10% of the movements occur during the 8 hour nighttimeperiod and that the remaining 90% are split evenly throughout thedaytime and evening hours. That is to say that the remainder is split75%/25% between the daytime and evening periods respectively. Due totheir 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 toSection 3 – Noise Modelling of Operations at a ‘Typical’ Airport 58

Methods of Assessment of Aircraft NoiseNigel Burtonthe night-time period. The results of these computations are presented inAppendix 3.3.4. Overview of Utilisation of the Integrated Noise ModelA detailed explanation of the modelling practices used for this investigation ispresented in Appendix 4 whilst a summary of the most salient points isprovided below.The Integrated Noise Model Version 6.0c has been utilised for the productionof the noise contours for this project. The software works under the MicrosoftWindows environment and can be used to calculate simple L max calculationsat specified locations or for more complex noise modelling processes such asthe calculation of noise contours around airports with multiple runway androute configurations. The in-built database contains noise data for around250 different aircraft types or variants. The software also contains layoutdata 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 thepreinstalled and custom edited metrics used in this case:Section 3 – Noise Modelling of Operations at a ‘Typical’ Airport 59

Methods of Assessment of Aircraft NoiseNigel BurtonNoise Noise Metric Flight Multiplier Averaging TimeMetric Family TypeDay 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 49.37CNEL A-Weighted Exposure 1 3 10 24 49.37LDEN A-Weighted Exposure 1 3 10 24 49.37LNIGHT A-Weighted Exposure 0 0 1 8 44.59LAEQ16 A-Weighted Exposure 1 1 0 16 47.60LAEQ8 A-Weighted Exposure 0 0 1 8 44.59Table 3.4.1: INM Noise Metric Data* The 10LogT term in the cases of NEF and ANEF is incorrect. Thefigure 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 noisecontour for that value. If the user defines a smaller grid, the low valuecontours may continue outside the grid boundary. This said, if the grid is toolarge, the computation time can be excessive. For the purposes of thisinvestigation, the standard grid size has been used and increased only whenthe 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 thisinvestigation these were set to 9 and 0.01 respectively. These values aredifferent to the default values but allow for greater precision in the calculationof the contour values, if increasing the run time slightly. Similarly, the “LowCutoff” and “High Cutoff” values were set to the minimum and maximumcontour values required for each metric. This allows the model to onlycompute values within the required range, reducing the run time of themodel.Section 3 – Noise Modelling of Operations at a ‘Typical’ Airport 60

Methods of Assessment of Aircraft NoiseNigel BurtonFor the contours produced for this project, the average run time was around2 to 3 minutes per metric. The model was run on a laptop with an AMD-K6 IIIprocessor with around 96 MB of RAM.Once the contours have been produced, they can be printed, to scale ifrequired, or can be exported as .DXF files for use in design packages suchas AutoCAD for overlaying onto geographical base maps.3.5. Results of the Computer ModellingThe graphical results of the contours produced for each metric are presentedin Appendix 5. The results for each metric are reviewed below individuallyand then compared against each other.3.5.1. Canada: Noise Exposure Forecast (NEF)The total areas covered by the NEF contours produced are presented inTable 3.5.1 with the contours themselves being presented in Figure 3.5.1:NEF Contour Value 25 30 35 40Area within Contour (sq. km) 25.07 11.78 5.30 2.27Table 3.5.1: Areas of NEF ContoursSection 3 – Noise Modelling of Operations at a ‘Typical’ Airport 61

Methods of Assessment of Aircraft NoiseNigel BurtonFigure 3.5.1: NEF Contour OutputsAssessing 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 newresidential development. The area between the 30 and 35 NEF contoursshould also not be used for new residential development but TransportCanada would offer guidance for those authorities that nevertheless wish toproceed. The area outside the 30 ANEF contour area of 11.78 sq.km “maybe acceptable” for new residential development and is likely to be acceptedwith the application of conditions, such as improved acoustic insulation, insome cases. It is noted that “Annoyance caused by aircraft noise may beginas low as 25 NEF”.3.5.2. Australia: Australian Noise Exposure Forecast (ANEF)The total areas covered by the ANEF contours produced are presented inTable 3.5.2 with the contours themselves being presented in Figure 3.5.2:ANEF Contour Value 20 25Area within Contour (sq.km) 38.56 17.22Table 3.5.2: Areas of ANEF ContoursSection 3 – Noise Modelling of Operations at a ‘Typical’ Airport 62

Methods of Assessment of Aircraft NoiseNigel BurtonFigure 3.5.2: ANEF Contour OutputsUsing the Australian criteria, new residential development would be deemedunacceptable within the ANEF 25 contour area of 17.22 sq.km. Use of thearea between the 20 and 25 ANEF contours for new residential developmentmay be permitted but with conditions applied, such as noise control. Landoutside 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 inTable 3.5.3 with the contours themselves being presented in Figure 3.5.3:DNL Contour Value 65 70 75Area within Contour (sq.km) 10.78 4.40 1.76Table 3.5.3: Areas of DNL ContoursSection 3 – Noise Modelling of Operations at a ‘Typical’ Airport 63

Methods of Assessment of Aircraft NoiseNigel BurtonFigure 3.5.3: DNL Contour OutputsUsing the United States’ criteria, new conventional residential developmentwill 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 70contour but in cases where permission is deemed appropriate, conditionsrelating to improved sound insulation should apply. For the area outside theDNL 65 contour area of 10.78 sq.km new residential developments would bepermitted “without restrictions”.3.5.4. USA: Community Noise Equivalent Level (CNEL)The total areas covered by the CNEL contours produced are presented inTable 3.5.4 with the contours themselves being presented in Figure 3.5.4:CNEL Contour Value 65 70 75Area within Contour (sq.km) 11.86 4.90 1.94Table 3.5.4: Areas of CNEL ContoursSection 3 – Noise Modelling of Operations at a ‘Typical’ Airport 64

Methods of Assessment of Aircraft NoiseNigel BurtonFigure 3.5.4: CNEL Contour OutputsUsing the State of California’s criteria, new conventional residentialdevelopment will not be permitted within the DNL 75 contour area of1.94 sq.km. Permission should also be refused for new residences within theDNL 70 contour but in cases where permission is deemed appropriate,conditions relating to improved sound insulation should apply. For the areaoutside the DNL 65 contour area of 11.86 sq.km new residentialdevelopments would be permitted “without restrictions”.3.5.5. European Union: L denThe total areas covered by the L den contours produced are presented inTable 3.5.5 with the contours themselves being presented in Figure 3.5.5:L den Contour Value 55 60 65 70 75Area within Contour 62.75 24.44 10.59 4.31 1.73(sq.km)Table 3.5.5: Areas of L den ContoursSection 3 – Noise Modelling of Operations at a ‘Typical’ Airport 65

Methods of Assessment of Aircraft NoiseNigel BurtonFigure 3.5.5: L den Contour OutputsAs stated earlier, the European Union has not set out any specific criteria inrelation to these contour values. The L den contour results will however becompared with the criteria established in the UK later.3.5.6. European Union: L nightThe total areas covered by the L night contours produced are presented inTable 3.5.6 with the contours themselves being presented in Figure 3.5.6:L night Contour Value 50 55 60 65 70Area within Contour 29.67 12.67 5.28 2.07 0.96(sq.km)Table 3.5.6: Areas of L night ContoursSection 3 – Noise Modelling of Operations at a ‘Typical’ Airport 66

Methods of Assessment of Aircraft NoiseNigel BurtonFigure 3.5.6: L night Contour OutputsAs stated earlier, the European Union has not set out any specific criteria inrelation to these contour values. The L night contour results will however becompared with the criteria established in the UK later.3.5.7. United Kingdom: L Aeq,16hrThe total areas covered by the L Aeq,16hr contours produced are presented inTable 3.5.7 with the contours themselves being presented in Figure 3.5.7:L Aeq,16hr Contour Value 57 66 72Area within Contour (sq.km) 27.25 5.82 1.91Table 3.5.7: Areas of L Aeq,16hr ContoursSection 3 – Noise Modelling of Operations at a ‘Typical’ Airport 67

Methods of Assessment of Aircraft NoiseNigel BurtonFigure 3.5.7: L Aeq,16hr Contour OutputsUsing the PPG 24 criteria adopted within the UK, for our hypothetical airportthe region within the 72 dB L Aeq,16hr contour area of 1.91 sq.km would beclassified as being in Noise Exposure Category (NEC) D where “Planningpermission should normally be refused”. For the area between the 66 and72 dB L Aeq,16hr contours, NEC C, “permission should not normally be granted”but where it is noise control conditions should be applied. For the areabetween the 57 and 66 dB L Aeq,16hr contours, NEC B, “Noise should be takeninto account when determining planning applications and, where appropriate,conditions imposed to ensure an adequate level of protection”. For theregion outside the 57 dB L Aeq,16hr contour area of 27.25 sq.km, NEC A, “Noiseneed not be considered” with regards to awarding of planning permission.3.5.8. United Kingdom: L Aeq,8hrThe total areas covered by the L Aeq,8hr contours produced are presented inTable 3.5.8 with the contours themselves being presented in Figure 3.5.8:Section 3 – Noise Modelling of Operations at a ‘Typical’ Airport 68

Methods of Assessment of Aircraft NoiseNigel BurtonL Aeq,8hr Contour Value 48 57 66Area within Contour (sq.km) 43.23 9.03 1.75Table 3.5.8: Areas of L Aeq,8hr ContoursFigure 3.5.8: L Aeq,8hr Contour OutputsUsing the PPG 24 criteria adopted within the UK, for our hypothetical airportthe region within the 66 dB L Aeq,8hr contour area of 1.75 sq.km would beclassified as being in NEC D where “Planning permission should normally berefused”. For the area between the 57 and 66 dB L Aeq,8hr contours, NEC C,“permission should not normally be granted” but where it is noise controlconditions should be applied. For the area between the 48 and 57 dB L Aeq,8hrcontours, NEC B, “Noise should be taken into account when determiningplanning applications and, where appropriate, conditions imposed to ensurean adequate level of protection”. For the region outside the 48 dB L Aeq,8hrcontour area of 43.23 sq.km, NEC A, “Noise need not be considered” withregards to the granting of planning permission.Section 3 – Noise Modelling of Operations at a ‘Typical’ Airport 69

Methods of Assessment of Aircraft NoiseNigel Burton3.5.9. Comparison of Residential Planning Criteria in Different RegionsAll of the regions, with the exception of the European Union, have residentialplanning criteria with regards to aircraft noise which can be crudely simplifiedinto three categories:1. Planning Permission Should Be Granted2. Planning Permission Could Be Granted (With Conditions)3. Planning Permission Should Be RefusedTable 3.5.9 compares the areas outside which planning permission should begranted for each of the metrics. The colour of the text in the first column ofthe table relates to the corresponding contour presented in Figure 3.5.9.Noise Metric Criteria AreaCanada: NEF < 30 NEF Outside 11.78 sq.kmAustralia: ANEF < 20 ANEF Outside 38.56 sq.kmUSA: DNL < 65 DNL Outside 10.78 sq.kmUSA: CNEL < 65 CNEL Outside 11.86 sq.kmUK: L Aeq,16hr < 57 dB L Aeq,16hr Outside 27.25 sq.kmUK: L Aeq,8hr < 48 dB L Aeq,8hr Outside 43.23 sq.kmTable 3.5.9: Areas for which Planning Permission Should Be GrantedSection 3 – Noise Modelling of Operations at a ‘Typical’ Airport 70

Methods of Assessment of Aircraft NoiseNigel BurtonFigure 3.5.9: Areas Outside Which Planning Permission Should Be GrantedTable 3.5.10compares the region in which planning permission could begranted with conditions for each of the metrics.Noise Metric Criteria AreaCanada: NEF 30-35 NEF 11.78-5.30 sq.kmAustralia: ANEF 20-25 ANEF 38.56-17.22 sq.kmUSA: DNL 65-75 DNL 10.78-1.76 sq.kmUSA: CNEL 65-75 CNEL 11.86-1.94 sq.kmUK: L Aeq,16hr 57-72 dB L Aeq,16hr 27.25-1.91 sq.kmUK: L Aeq,8hr 48-66 dB L Aeq,8hr 43.23-1.75 sq.kmTable 3.5.10: Areas for which Planning Permission Could Be Granted (WithConditions)Table 3.5.11 compares the areas for which planning permission should berefused for each of the metrics. The colour of the text in the first column ofthe table relates to the corresponding contour presented in Figure 3.5.10.Section 3 – Noise Modelling of Operations at a ‘Typical’ Airport 71

Methods of Assessment of Aircraft NoiseNigel BurtonNoise Metric Criteria AreaCanada: NEF > 35 NEF Inside 5.30 sq.kmAustralia: ANEF > 25 ANEF Inside 17.22 sq.kmUSA: DNL > 75 DNL Inside 1.76 sq.kmUSA: CNEL > 75 CNEL Inside 1.94 sq.kmUK: L Aeq,16hr > 72 dB L Aeq,16hr Inside 1.91 sq.kmUK: L Aeq,8hr > 66 dB L Aeq,8hr Inside 1.75 sq.kmTable 3.5.11: Areas for which Planning Permission Should Be RefusedFigure 3.5.10: Areas inside which Planning Permission Should Be RefusedFinally, a comparison of the residential planning criteria in the differentregions examined is presented below in the form of a cumulative bar chart inFigure 3.5.11.Section 3 – Noise Modelling of Operations at a ‘Typical’ Airport 72

Methods of Assessment of Aircraft Noise Nigel Burton50454035Area (sq.km)302520151050Canada: NEF Australia: ANEF USA: DNL USA: CNEL UK: LAeq,16hr UK: LAeq,8hrMetricPermission Should Be Refused Permission Could Be Granted (With Conditions) Permission Should Be GrantedFigure 3.5.11: Comparison of Residential Planning Criteria in Different RegionsSection 3 – Noise Modelling of Operations at a ‘Typical’ Airport 73

Methods of Assessment of Aircraft NoiseNigel Burton3.6. Discussion of ResultsThe results of the modelling exercise indicate large variations in the planningcriteria adopted in the different regions examined. The criteria adopted inAustralia appears to the be the most stringent having a comparatively largearea, 17.22 sq. km, within which residential development should be refusedon noise grounds.Conversely, the least stringent region with regards to aircraft noise appearsto be the USA. The total areas for which development should be refused andcould be granted with conditions within this country, using either the DNL orthe CNEL system, would fit within the area for which planning permissionshould be refused assuming the Australian criteria.With regards to the UK systems, the areas within which residentialdevelopment should be refused are similar to those predicted under the USAsystems, at around 1.7 to 2.0 sq.km. This said, the UK criteria is morestringent than the USA criteria by having a far larger area in which conditionswould be applied before residential development would be permitted withoutcondition.The contour area for the 57 dB L Aeq,16hr , the area outside which residentialdevelopment should be permitted within the UK, is similar to the areaencompassed by the 60 dB L den contour under the EU system. The contourarea for the 72 dB L Aeq,16hr , the area inside which residential developmentshould be refused within the UK, is similar to the area encompassed by the75 dB L den contour under the EU system. It is important to remember,however, that this relationship is only true for this scenario since the UKmetric is based purely on 16 hour daytime and evening movements whilst theEU system also takes account of night-time movements.The UK L Aeq,8hr and EU L night are identical metrics. Therefore, the nearestL night contour produced to the 48 dB L Aeq,8hr contour, outside which residentialdevelopment should be permitted, is the 50 dB L night contour. Similarly, theSection 3 – Noise Modelling of Operations at a ‘Typical’ Airport 74

Methods of Assessment of Aircraft NoiseNigel Burtonnearest L night contour produced to the 66 dB L Aeq,8hr contour, inside whichresidential development should be refused, is the 65 dB L night.Section 3 – Noise Modelling of Operations at a ‘Typical’ Airport 75

Methods of Assessment of Aircraft NoiseNigel Burton4.0 SECTION 4 – SUMMARY, CONCLUSIONS AND AREAS FORFURTHER WORKIt has been demonstrated that a variety of different systems have been andare being used for assessment of aircraft noise both historically and aroundthe world.Of the methods examined in the last section of this report, the AustralianANEF system, coupled with its corresponding criteria in that country, appearsto be the most stringent, with the systems and criteria adopted in the USAbeing the least strict. From the literature reviewed in Section 2, theAustralian government also appear to be actively encouraging the discussionof aircraft noise in order to develop new methods to better communicate theeffects of aircraft operations to the layperson. The promotion of the use ofarithmetic noise metrics such as the N70 appears to be assisting thisprocess.The opinion of this Author is that a common approach to the assessment ofaircraft noise would be beneficial in order to allow easy comparison of noiseexposures around different airports throughout the world. Whilst it would alsobe beneficial for similar criteria to be adopted internationally, it is appreciatedthat this is less likely to occur due to the apparent large variation in thedefinition of what constitutes acceptable and unacceptable levels of aircraftnoise. A definitive answer as to what is and is not acceptable is unlikely tobe found since, as stated in the Department of Transport Press Notice 304 in1990 “There is no absolute measure of disturbance from aircraft noise – norcan there be, given the variation in individual reactions” 5 .Areas that could be examined for further work in this area would include theuse and review of the new Australian aircraft noise assessment softwareTNIP described in Section 2.5.3. As explained in that section, this authorattempted to obtain a copy of this freeware software but has yet to receive it.Section 4 – Summary, Conclusions and Further Work 76

Methods of Assessment of Aircraft NoiseNigel BurtonIt may also be beneficial to repeat this pilot study using actual data forvarious major international airports, assessing the noise exposure at eachwith different noise metrics and criteria adopted elsewhere. It would also beinteresting to determine whether human response to aircraft noise exposurediffers from region to region. This could be examined by carrying outcarefully constructed surveys of people living and working around the variousairports in question, similar to those carried out on behalf of the WilsonCommittee over 40 years ago.Section 4 – Summary, Conclusions and Further Work 77

Methods of Assessment of Aircraft NoiseNigel Burton5.0 SECTION 5 – REFERENCES1 Committee on the Problem of Noise. Noise Final Report, HMSO, Cmnd.2056, July 19632 Office of Population Censuses and Surveys, Social Survey Division, Second Survey ofAircraft Noise Annoyance around London (Heathrow) Airport, 19713 NELSON P: Transportation Noise Reference Book Butterworths & Co. (Publishers) Ltd,19874 BROOKER P, CRITCHLEY J B, MONKMAN D J, RICHMOND C: DR Report 8402 UnitedKingdom Aircraft Noise Index Study: main report – Civil Aviation Authority Directorate ofResearch and Analysis (DORA) Jan 19855 Department of Transport, Press Notice No 304, Change Agreed To Daytime Index forAircraft Noise, 4 September 19906 CRICHLEY J B, OLLERHEAD J B: DORA Report 9023 The Use of Leq as an Aircraft NoiseIndex – Civil Aviation Authority Directorate of Research and Analysis (DORA) September19907 DEPARTMENT OF ENVIRONMENT Planning Policy Guidance Note 24 (PPG 24):Planning and Noise September 19948 DEPARTMENT OF TRANSPORT The Future of Air Transport December 20029 http://www.uk-airportparking.co.uk/heathrow (Heathrow Airport Parking History) Accessed27/08/0310 http://www.heathrow.airport-parking-centre.co.uk/about-heathrow-airport.html (AboutHeathrow Airport - Facts, Figures and History) Accessed 27/08/0311 http://www.heathrow-airport-parking-uk.co.uk/heathrow-history/ (Heathrow Airport History)Accessed 27/08/0312 http://www.heathrow-airport-guide.co.uk/history.html (Heathrow Airport Guide - History ofLondon Heathrow Airport) Accessed 27/08/0313 http://www.parkandgo.co.uk/heathrow-airport-history.html (Park and Go: Heathrow AirportParking – Airport History) Accessed 27/08/0314 HARRIS MILLER MILLER & HANSON Inc: Reid-Hillview Airport FAR Part 150 Draft NoiseExposure Map 200215 Federal Interagency Committee on Noise (FICON) Federal Agency Review of SelectedAirport Noise Analysis Issues August 199216 Schultz, T.J. Synthesis of Social Surveys on Noise Annoyance Journal of the AcousticalSociety of America, Vol.64, No.2, August 197817 Personal Correspondence with Tom Lowrey of Transport Canada18 Transport Canada, TP 1247E – Land Use in the Vicinity of Airports, Part IV – AircraftNoise, 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 AssociatedLand Use Compatibility Advice for Areas in the Vicinity of Airports, Fifth Edition September199920 Senate Select Committee on Aircraft Noise in Sydney: Falling on Deaf EarsCommonwealth of Australia, Canberra, 199521 Department of Transport and Regional Services, Australia – Discussion Paper: ExpandingWays to Describe and Assess Aircraft Noise – March 200022 HEDE A J, BULLEN R B Aircraft Noise in Australia: A Survey of Community Reaction,NAL Report No.88 National Acoustic Laboratories, Australian Government PublishingServices, Canberra, 198223 Australian Standard AS2021-1994 Acoustics – Aircraft noise intrusion – Building siting andconstruction24 FLINDELL I H, MCKENZIE A R European Environment Agency – Technical Report – AnInventory of Current European Methodologies and Procedures for Environmental NoiseManagement – 26 June 2000 – European Environment Agency, Denmark25 European Parliament Directive 2002/49/EC of the European Parliament and of the Councilof 25 June 2002 relating to the assessment and management of environmental noise June200226 GULDING, OLMSTEAD, BRYAN, MIRSKY, FLEMING, D’APRILE, GERBI IntegratedNoise Model 6.0 User’s Manual Federal Aviation Administration September 1999Section 5 – References 78

Methods of Assessment of Aircraft NoiseNigel Burton27 Department of Transport and Regional Services, Australia – TNIP Transparent NoiseInformation Package – User’s Manual TNIP v3.2.2 – December 200328 http://www.sfu.ca/sonic-studio/handbook/Noise_Exposure_Forecast.html(Noise_Exposure_Forecast - Noise Exposure Forecast (NEF)) Accessed 22/09/0329 http://www.netvista.net/~hpb/epa1974/epa19741.html (Equivalent Sound Level and ItsRelationship to Other Noise Measures) Accessed 25/01/0430 http://www2.sfu.ca/sonic-studio/handbook/Community_Noise_Equivalent.html (CommunityNoise Equivalent Level (CNEL)) Accessed 06/01/04Section 5 – References 79

Embraer 145 Dash 8Airbus A319Airbus A320Boeing 737-700 Boeing 737-800Appendix 1: Photographs of Examples of Aircraft Used for Noise ModelsPage 1 of 2

Airbus A310 Boeing 757Boeing 767Airbus A300Airbus A330Appendix 1: Photographs of Examples of Aircraft Used for Noise ModelsPage 2 of 2

For DNL, CNEL, NEF and ANEFDAYTIME (07:00-19:00)ARR DEP DEP ARR DEP DEPINM Type Sector 9 09N 09S 27 27N 27S737700 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 20.6010A32023 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 12.474072.9000 14.5800 58.3200 170.1000 34.0200 136.0800145.8 340.2486EVENING (19:00-22:00)ARR DEP DEP ARR DEP DEPINM Type Sector 9 09N 09S 27 27N 27S737700 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 5.1503A32023 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 3.118518.2250 3.6450 14.5800 42.5250 8.5050 34.020036.45 85.05121.5NIGHT-TIME (22:00-07:00)ARR DEP DEP ARR DEP DEPINM Type Sector 9 09N 09S 27 27N 27S737700 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 4.7688A32023 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 2.887516.8750 3.3750 13.5000 39.3750 7.8750 31.500033.75 78.75112.5Appendix 3: 15 Hour Day Scenario INM Input Data

For DNL, CNEL, NEF and ANEFDAYTIME (07:00-19:00)ARR DEP DEP ARR DEP DEPINM Type Sector 9 09N 09S 27 27N 27S737700 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 20.6010A32023 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 12.474072.9000 14.5800 58.3200 170.1000 34.0200 136.0800145.8 340.2486EVENING (19:00-22:00)ARR DEP DEP ARR DEP DEPINM Type Sector 9 09N 09S 27 27N 27S737700 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 5.1503A32023 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 3.118518.2250 3.6450 14.5800 42.5250 8.5050 34.020036.45 85.05121.5NIGHT-TIME (22:00-07:00)ARR DEP DEP ARR DEP DEPINM Type Sector 9 09N 09S 27 27N 27S737700 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 4.7688A32023 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 2.887516.8750 3.3750 13.5000 39.3750 7.8750 31.500033.75 78.75112.5Appendix 3: 15 Hour Day Scenario INM Input Data

Appendix 4: Utilisation of Integrated Noise Model SoftwareThe Integrated Noise Model Version 6.0c has been utilised for the production ofthe noise contours for this project. The software works under the MicrosoftWindows environment and can be used to calculate simple L max calculations atspecified locations or more complex noise modelling such as the calculation ofnoise contours around airports with multiple runway and route configurations.The in-built database contains noise data for around 250 different aircraft typesor variants. The software also contains layout data for around 820 airportswithin the USA. For the purposes of this project, an original study is to be setup, the basic processes of which are described below. It should be noted thatthe 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 theoperations take place.• When the INM software has loaded, the “New Study” function is selectedfrom 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 thedirectory path where the study will be saved. Click “OK”• Upon completion, you are asked “Do you want to create a new study in” andthen the path name. Click “Yes”• Next, you are asked to “Select the units to use for your study” where theoptions 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 canbe typed. The “Origin of Coordinates” screen can be used if a preinstalledUS 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 areto be used on this occasion. If a US airport were selected, information suchas 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 canbe 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 byhighlighting the choice followed by the “Include” button. The chosen aircrafttype 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, theINM manual can be consulted to find a suitable “substitute aircraft”. This isnot 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 ofthe 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 thissection will already have been loaded. In this case we will input thisinformation 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 “RunwayEnd #1” and “Runway End #2” and determine the width of the runway inmetres, followed by Ctrl + Enter to commit the details to the software. In thisAppendix 4: Utilisation of Integrated Noise Model Software 2

case, the runway ends have been named “09” and “27” and a runway widthof 50m has been chosen.• If additional runways are required, press Ctrl + A, else close the dialoguebox.• Next, select the “Runway Ends” option from the “Tracks” menu. Thedialogue box will appear where the user can determine the location of therunway ends in relation to the origin and edit other parameters such asdisplaced thresholds, glide slope, etc. In this case, the centre of the runwayhas been taken as the origin and runs east to west. Therefore the location ofthe “09” end is –1.5250 km from the origin on the x-axis and 0 km from theorigin on the y-axis whilst the “27” end is +1.5250 km from the origin on thex-axis and 0 km from the origin on the y-axis, thus the runway is 3050m inlength. No displaced thresholds have been specified and the standardglideslope of 3° has been adopted. Close the dialogue box.• Now select the “Track Identifiers” option from the “Tracks” menu. A dialoguebox appears in which the tracks for each runway can be specified. In thiscase we have specified one arrival and two departure tracks for eachrunway. Other options such as “sub-track” and “percentage operations” canalso be detailed here but have not been used on this occasion. Close thedialogue box.• Finally select the “Track Segments” option from the “Tracks” menu. Here theuser 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 usedfor each; one straight section followed by a turn followed by a straightsection. 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. Closethe dialogue box.Appendix 4: Utilisation of Integrated Noise Model Software 3

Setting up the Metrics• This section need only be viewed if, as in this case, custom metrics that arenot installed within the software are required.• From the “Setup” menu, select the “metrics” option. A dialogue box willappear containing the inbuilt metrics. These are ‘greyed out’ such that theycannot be edited. Each metric has a title, or “Metric ID” and belongs to anoise “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 tothe different weighting given to daytime, evening and night-time movements.The averaging time, specified as 10 LOG T in seconds, relates to the timeperiod 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. TableA below shows the information used to calculate both the preinstalled andcustom edited metrics used in this case:Noise Noise Metric Flight Multiplier Averaging TimeMetric Family TypeDay 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 49.37CNEL A-Weighted Exposure 1 3 10 24 49.37LDEN A-Weighted Exposure 1 3 10 24 49.37LNIGHT A-Weighted Exposure 0 0 1 8 44.59LAEQ16 A-Weighted Exposure 1 1 0 16 47.60LAEQ8 A-Weighted Exposure 0 0 1 8 44.59Table A: INM Noise Metric DataAppendix 4: Utilisation of Integrated Noise Model Software 4

* The 10LogT term in the cases of NEF and ANEF is incorrect. The figure of88 relates to the -88 in the calculation for each of these metrics.• Close the dialogue boxCreating Cases and Inputting Aircraft Movement Data• Under the “Setup” menu, select the “Cases” Option. A dialogue box willappear where a new case can be set-up by pressing Ctrl + A. The user mustenter a “Case ID” and a short description can also be input. “AirportParameters” such as temperature and headwind can be edited at this stagebut the default settings have been used in this case. For the purposes of thisexercise, two cases have been set up entitled “15 hour Day Scenario” and“16 hour Day Scenario”. After inputting the information for a case, the usershould 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 willappear 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. Herethe user can enter flight information for the daytime, evening and night-timeperiods by aircraft type, runway, operation and route. The stage length ofthe aircraft departures can also be specified under the “Profile ID” option. Toinput 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 andrunways.• With a large amount of data to be input, as in this case, this can be a ratherarduous task. Although the INM software saves this information as databasefiles, no simpler way of entering this information has been found by thisauthor.Appendix 4: Utilisation of Integrated Noise Model Software 5

• Upon completion of data entry for this case, the dialogue box should beclosed. If another case is required, as is for this assessment, the processshould 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 thecases. Under the “Run” menu, select the “Grid Setup” option. A dialoguebox will appear where the user must select which case is required. Selectthe desired case by highlighting it and click “OK”.• The Grid is basically the area over which the INM package will calculate thenoise levels of the aircraft. If it is too small, the low value contours maycontinue outside the grid boundary. This said, if the grid is too large, thecomputation time could be very long. In this case, the standard grid size hasbeen used and increased only when the model has been run and it has beenfound that the grid size is too small. To add a grid, press Ctrl + A, and selecteither a “Contour”, “Standard”, “Detailed”, “Location” or Population grid. Forthe purposes of creating contours for this assessment, a Contour grid hasbeen chosen. The grid size can be adjusted by editing the “Grid Origin” andthe “Distance Between Points” option. Close the dialogue box.• Next select “Run Options” from the “Run” menu. The “Run Options” dialoguebox will appear in which the noise metrics to be run for each of the cases canbe specified. Cases can be run for “Single-Metric” or “Multi-Metric”scenarios. On this occasion the cases have been run for single metrics andre-run for each metric. The “Do contours” options is highlighted and the“refinement” and “tolerance” set to 9 and 0.01 respectively. These aredifferent to the default values but allow for greater precision in the calculationof the contour values, if increasing the run time slightly. The “Low Cutoff”Appendix 4: Utilisation of Integrated Noise Model Software 6

and “High Cutoff” values are then set to the minimum and maximum contourvalues required. Close the dialogue box.• From the “Output” menu, select the “Output Setup” option. This is where thecontour values to be produced are selected. The case for which the outputsare required should be highlighted in the left hand box and “Metric” and“Contour Levels” specified. The metric should be similar to that specified inthe “Run Options” menu and the maximum and minimum contour levelsshould be between the low and high cutoff values. The increments betweencontours 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 areusually only interested in increments of say 3 or 5 dB. Close the dialoguebox.• 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 thecases to be included, in a similar fashion to the way in which the aircraft forthe study were chosen. Upon selection, click “OK”. The INM software willnow run the chosen case(s) whilst showing a “percentage done” value. Forthe contours for this project, the average run time was around 2 to 3 minuteson 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 byselecting the “Output Graphics” option from the “Output” menu. Again, theuser is asked to specify the output from which case are to be viewed. Selectthe desired case and press “OK”. At this stage the contours have not becomputed, merely the noise levels across the grid. The contours are nowcalculated and appear in a window on the screen.• From the “Contour Display Control” dialogue box the colour and fill of thecontours can be altered as well as the inclusion or exclusion of contourlabels. From the “File” menu the contours can be printed, to scale ifrequired, or can be exported as .DXF files for use in design packages suchas AutoCAD.Appendix 4: Utilisation of Integrated Noise Model Software 7

APPENDIX 5RESULTANT NOISE CONTOURS FROM MODELLING EXERCISE

INM 6.1 30-Jan-04 12:0215 Hr Day Scenario OUTScale 1 cm = 500 mNEFsq.kmcolor25.025.0730.011.7835.05.3040.02.27

INM 6.1 30-Jan-04 12:1115 Hr Day Scenario OUTScale 1 cm = 500 mANEFsq.kmcolor20.025.038.5617.22

INM 6.1 30-Jan-04 11:3915 Hr Day Scenario OUTScale 1 cm = 500 mDNLsq.kmcolor65.010.7870.04.4075.01.76

INM 6.1 30-Jan-04 11:5415 Hr Day Scenario OUTScale 1 cm = 500 mCNELsq.kmcolor65.011.8670.04.9075.01.94

INM 6.1 30-Jan-04 11:1116 Hr Day Scenario OUTScale 1 cm = 500 mLDENsq.kmcolor55.062.7560.024.4465.010.5970.04.3175.01.73

INM 6.1 30-Jan-04 11:2216 Hr Day Scenario OUTScale 1 cm = 500 mLNIGHTsq.kmcolor50.029.6755.012.6760.05.2865.02.0770.00.96

INM 6.1 30-Jan-04 10:3016 Hr Day Scenario OUTScale 1 cm = 500 mLAEQ16sq.kmcolor57.027.2566.05.8272.01.91

INM 6.1 30-Jan-04 10:4416 Hr Day Scenario OUTScale 1 cm = 500 mLAEQ8sq.kmcolor48.043.2357.09.0366.01.75