The NPS acknowledges that noise can have a significant impact on communities, and “there is growing evidence that exposure to high levels of aircraft noise can adversely affect people’s health.” This is consistent with work from the University of London, prepared for the Airports Commission, which concluded that “the health effects of environmental noise are diverse, serious, and because of widespread exposure, very prevalent. For populations around airports, aircraft noise exposure can be chronic.”
Expansion at Heathrow will lead to a rise of around 700 flights per day compared to a no expansion scenario. The NWR scheme is estimated to cause significant annoyance for 653,900 people in 2030, as well as 263 noise sensitive buildings. This is 92,700 more people than would be impacted without expansion. For comparison, the Gatwick and ENR schemes are estimated to impact an additional 16,200 and 27,200 people in 2030 (figure below). The ENR scheme is estimated to result in a net improvement in terms of the number of people captured in the noise envelope by the end of the appraisal period. The difference between the Heathrow and Gatwick proposals reflect the fact that Gatwick expansion is over a largely rural area. It is not unpopulated, but it is largely rural compared with the expansion at Heathrow.
Figure 41: Comparison of expansion options and the resulting noise annoyance for nearby residents
The NWR scheme will also result in an increase of around 20,000 people impacted by noise levels that are acknowledged by the government to contribute to premature deaths (figure below).
Figure 42: NWR Local Airspace >63 dB Daytime Average Noise SOAEL Population Exposure
It is, of course, impossible to know with absolute certainty what the exact noise outcomes of a NWR will be without actual flight-paths. Noise modelling has been produced to support the NPS based on indicative flight-paths. But as with any other forecasting, the outputs of the noise modelling are only as good as the assumptions fed into the modelling. The noise outputs are driven by various, and at times, uncertain assumptions around future aircraft traffic, flight-paths, aircraft noise efficiency and population densities. The noise outputs can also be represented in different ways, using different metrics and at different thresholds.
Several submissions have shone a light on the validity of key assumptions used by the DfT in developing the latest round of the noise estimates. Further investigations suggest that the noise picture portrayed by the DfT is unlikely to reflect the eventual noise impact of the scheme. The issues dealt with below can come across as overly technical but the impacts on the headline figures, which ultimately shape public perceptions and acceptability of this scheme, are profound.
Appendix A-4 of the DfT’s Appraisal of Sustainability presents the latest result of the noise modelling work commissioned by the DfT to support the NPS. It has been updated using the DfT’s latest aviation demand forecasts and shows overall populations affected by noise and the net change in noise exposure at three different thresholds.
The presentation of the modelling work using ‘net figures’ presents a slightly skewed picture and does not reflect the political realities of how noise changes will be received by communities. The DfT’s approach nets out the ‘winners’ and ‘losers’ from noise changes. Yet community acceptability is often shaped much more by the ‘losers’ who have a much lower tolerance to equivalent levels of noise to people who’ve been exposed over long periods. This was explained by John Stewart of HACAN:
If people grew up under the flightpath or have lived with it for some time, they find it easier to live with than if they come across noise for the first time. But that, of course, is the big problem for the third runway. However much respite you get, there will be a third flightpath and that will bring people who have not had noise under it for the first time. They will undoubtedly feel more affected than people who have lived with it for quite some time.
On this basis, a more revealing metric—which is not presented in the appraisal work supporting the NPS—might be the gross number of people who will be newly exposed to significant levels of noise annoyance.The figure below shows that substantially more people will be newly affected by significant noise annoyance with the NWR scheme than the other proposals.
Figure 43: Number of people newly affected by significant noise annoyance (>54dB), by expansion option, 2030
The figure below shows the gross number of people who will be exposed to worse noise above the significant noise annoyance thresholds across the three schemes. That is, they are either newly affected by this level of noise or were already above this threshold and are exposed to higher levels of noise. Again, it shows that more people will be experience worse and significant noise annoyance with the NWR scheme than the other proposals.
Figure 44: Number of people exposed to worse noise, at or above the 54dB threshold, by expansion option
A baseline (or ‘do-minimum) is developed in the noise modelling to understand what the noise footprint at Heathrow would be with and without an extra runway. Any changes should reflect factors related specifically to expansion (e.g. having more ATMs, different flight-paths and operational procedures). Other factors such as industry-wide aircraft or airspace changes would usually be applied equally across the baseline and expansion options. This is to ensure expansion and no-expansion outcomes are compared on a like-for-like basis.
It is not entirely clear whether this is the case in the noise modelling used to support the NPS. As revealed in the figure below, the noise efficiency improvements are considerably greater in a scenario of expansion than no-expansion (figure below). In other words, the noise footprint is getting smaller at a much greater rate with expansion than without.
Figure 45: Change in noise efficiency, no expansion vs NWR expansion, from 2016
Transport for London believe that the current modelling approach does not provide a sound basis for comparison. Specifically, it believes the noise modelling for the NWR relies on new technology and related operational innovations which are optimistic and unrelated to expansion. Stephen Clark, Dave Gilbert and Katie Williams also criticised the lack of comparability between the baseline and expansion modelling:
[ … ] the Do Minimum (DM) scenario is not optimised in the way the change (third runway) option is. In order to undertake a proper analysis with a level playing field, the base case should have assumed flight paths could be varied, included deeper landings into the airport and steeper descents introduced to reduce impacts, as this can occur without expansion.
Measuring noise is complex and inevitably involves a simplification of the complexity of human responses to noise in real situations. Because of this, typically a series of metrics and at different thresholds (i.e. the noise scorecard) are used to assess the scale of noise impact. This is reflected in national policy.
The revised NPS states that the “the noise scorecard [supporting the NPS] includes both conventional metrics and more innovative metrics.” It should be noted that the NPS noise analysis relies on fewer metrics and at fewer thresholds of noise than was developed by the Airports Commission. Because the DfT is almost entirely reliant on the noise contour approach, it has failed to apply best practice in its noise assessment. The noise contour method essentially measures noise for a certain period during the day and averages that out over several months. For example, the “54 dB LAeq,16h” metric–which is the primary one used by the DfT–is the average summertime daytime/evening period of noise between 7am and 11pm. Average noise is then represented through noise contour maps that illustrate the different areas around Heathrow impacted at different thresholds (figure below).
Figure 46: Noise contour map in 2030 as estimated by the Airports Commission—Minimise Total scenario
Several witnesses argued that this averaging approach misrepresents the scale of people impacted by noise, particularly because it ignores areas that planes may fly over for part of the year but, when they do so, are badly hit. On days where the airport is running easterly operations, for example, places such as Teddington and Ealing are overflown intensely. Stephen Clark said that on such days Teddington suffers over 17 hours of continuous noise from 400+ flights, concentrated in early morning and very late evening. Yet these places fall outside the annoyance contours because non-noise days are included in the averaging method.
It is also argued that averaging noise gives too much weight to the noise of individual aircraft, which is on the whole falling, and not enough weight to the number of planes, which will rise. John Stewart of HACAN also said that “our members do not hear average noise.” HACAN have been arguing for some time that “a suite of metrics should be used rather than just relying exclusively on the averaging.” For example, metrics are available to count the number of planes that go overhead at certain decibel levels (e.g. ‘N60’ measures many planes go overhead at 60 decibels or more). These metrics are not used in the analysis supporting the revised NPS even though it is now accepted as a core metric by the DfT.
Noise thresholds used by the DfT in the draft NPS are not in-line with its own guidance that accepts the onset of annoyance at 51 dBLAeq. The analysis supporting the NPS does not publish the number of people affected at this level and only uses a higher threshold of 54 dBLAeq. While at face value, this may not appear to look like much of a difference, a difference of even 3 dBALeq is equivalent to doubling of noise events. As shown in figure 47 below, if the threshold of annoyance was extended down to the 51dB level, an extra 539,327 people would be captured in the annoyance footprint.
Figure 47: Local noise population impacts, at different thresholds of noise, NWR option
The noise modelling conducted by the Airports Commission used three sets of ‘indicative’ flight path designs. Using different sets of flight-paths is a preferred approach as there are uncertainties as to how flight-paths will be designed in practice because of technical and safety feasibilities, as well as community preferences around respite, dispersal and concentration. The DfT only considered one set of flight paths that are more concentrated. This set of flight paths see fewer people overflown but much more often (first figure below). This compares with one that offers more respite by alternating flight-paths. This results in more people being affected, but for a shorter time than the set of flight-paths used by the Department. (second figure below).
Figure 48: Proposed Heathrow flight-paths—less flight-path alternation
Figure 49: Proposed Heathrow flight-paths—more flight-path alternation
Explaining the approach taken by the DfT, Caroline Low said:
At this stage we are trying to give an overall sense of the impacts of building at Heathrow versus Gatwick. The commission ran a range of noise flightpaths. When we updated the demand analysis, we just updated one set of noise contours around one set of flightpaths in order to give a very good sense of what those demand changes did to the noise contours.
The flight-paths the Department has chosen to model do not appear to be consistent with the policy of respite as stated in the NPS and, in practice, are unlikely to be realised because of the political and community hurdles that come with concentrating flight-paths. John Stewart commented on community expectations with respect to flight-paths:
[ … ] we are very keen that flightpaths are not concentrated over particular communities all the time … we believe there should be a number of flightpaths so that during the course of the day those flightpaths can be rotated and every community can get an element of respite.
Caroline Low said during oral evidence that the DfT’s analysis “was not intended to prejudge that [airspace change] process.” By estimating only one of a possible multitude of scenarios, the DfT’s analysis has not provided people with a full view of the range of noise impacts. During oral evidence, Caroline Low said that “you can look back to the work the Airports Commission did to understand the relatively small differences in the number of people affected through using different flightpaths.” But looking at the noise modelling from the Commission, the results vary significantly and the set of flight paths chosen by the DfT (NWR-T) had significantly smaller noise footprints than some of the other scenarios assessed by the Airports Commission.
Figure 50: Noise footprint of flight-path scenarios, change against the baseline, 2030
The DfT’s noise forecasts appear to be considerably more optimistic about the levels of noise reduction that can be achieved over the appraisal period than the Airports Commission (figure below). These noise reductions have occurred because of the new fleet assumptions to those used by the Airports Commission. In response to whether things have changed that substantially since the Airports Commission did their work, Lucy Chadwick believed they had taken a reasonable conservative approach:
Yes, they have. The airlines are bringing on some of those newer fleets because they offer far greater fuel efficiency. The leasing models they have allow them much easier access to them. What had been historical for turnover rates we have seen increasing substantially.
Figure 51: Difference in local noise estimates, number of people affected–Airports Commission vs the DfT
The Secretary of State also endorsed this view and said that “aircraft are getting quieter all the time. The new generation of aircraft are a fraction of the noise levels of the existing ones” and said the Government had “still taken a conservative projection forward.” Andrew Haines also believed “the assumptions in the Airports Commission modelling have been bettered in reality since then. We have quite a few 787s and A350s in practice, and they are materially quieter than was predicted.” HAL referred to the greater use of twin-engine aircraft, including 777 series aircraft and the more recent introduction of the 787 ‘Dreamliner’, the Airbus A350 and A320 Neo aircraft, as evidence of the noise improvements being made by new aircraft.
The more favourable noise assumptions used by the DfT are not insignificant and represent a doubling, or in some cases, tripling of the anticipated noise reductions from new fleets flying in and out of Heathrow, with shorter transition periods. Lord Deben believed the lack of turnover in aircraft was a major issue for the aviation sector in delivering improved environmental outcomes:
I have forgotten the figures, but a huge proportion of the aeroplanes that have ever been in the air are still in the air. It is remarkable how long-lasting they are, so, if you want to reduce that and have more efficient aeroplanes, you will have to be pretty tough.
The Department chose not to update fleet assumptions as part of the February 2017 appraisal. It has also not provided any documentation to support its new assumptions. Given how significant these assumptions are to the headline figures and the overall impact of this scheme, it is surprising that the Department has not provided any substantive information to justify these new assumptions (see figure 52).
Figure 52: Noise improvements, First Generation Fleet Assumptions, DfT vs Airports Commission, dB
The NPS states that periods of respite will be offered to nearby communities but that “the timings, duration and scheduling should be defined in consultation with communities and relevant stakeholders.” Communities around Heathrow currently have a respite period of half the flying day, resulting from a switch in runway use, where planes are not overhead. The NPS states that this will reduce to one third of the day with a NWR. Were this to be the case, areas such as Richmond—which currently benefits from 8 hours of respite a day—may see their respite reduced. Stephen Clark put the anticipated change of respite into context:
People in Richmond are getting eight hours’ respite at the moment. They get flights two days in every three. For half a day it is tranquil, and for half a day they get flights. Now it is proposed that they will get 12 hours of flights with far less tranquillity. It will have a massive impact, even if you are already under flights. The point I am making is that you will get intensification. There will be new people and there will be people affected by intensification.
When asked about their respite proposals John Holland-Kaye said that he did “not recognise” the statement in the NPS about a reduction in respite from a half to a third of the day. Emma Gilthorpe also said that it was too “premature to suggest a specific amount of time” and said that HAL were currently consulting on respite options.
According to the Joint Boroughs, “without an agreed definition of the term the concept is meaningless.” The Environmental Audit Committee believed the NPS lacked clarity on how predictable respite would be achieved and recommended the Government carry out further work on respite which should form part of the NPS process. The No Third Runway Coalition believed that “there is insufficient information in the NPS on the length of the respite period that communities will experience should a third runway become operational [and] the lack of flight path information means it is not possible to estimate how many will be affected.”
There is currently five hours at night without scheduled flights is currently between 11.30 pm and 4.30 in the morning. A night flight ban, as defined in the NPS, “involves a ban on scheduled night flights for a period of six and a half hours [ … ] between 11pm and 7am.” HAL are specifically proposing to go to six and a half hours, between 11 pm and 5.30 in the morning.” (figure below)
Figure 53: Current and proposed night flight proposals
A night-flight ban was universally accepted by community groups as a desired initiative; though it has received criticised by community groups because:
HAL believe that “any proposal for a ban on night flights during the whole 8-hour night period would in our view be undeliverable at Heathrow, even with expansion.” All of the airlines expressed concern at the current respite proposals. BAR UK believed the night-flight ban would not deliver the best possible respite for local communities and undermine the NPS objectives related to UK hub connectivity and competitiveness.Rafael Schvartzman also believed a “rigid ban will limit both competitiveness and the options to deliver a more flexible and efficient use of expansion.”
Airlines UK recommend that “any changes to the night flights regime affecting airport operating hours[ … ] should not be made without a full and comprehensive consultation with those affected, and a proper understanding of the impacts of such changes.” The airline community, represented by the Heathrow Airport Scheduling Committee, have put forth an alternative proposal that follows the ICAO balanced approach and which they believe “might be able to offer seven hours and not six and a half” of respite.
HACAN put a similarly flexible proposal forth, which “could be possible for eight hours to be the norm for communities during the course of the year.” John Stewart explained the approach:
Right now, between 6 o’clock and 7 o’clock is the busiest hour of the day, when both runways are used. If you were able to move some of the flights that currently arrive between 6 and 7 to just after 7 o’clock on the extra capacity for a third runway, you could just have one runway used between 6 and 7 o’clock. If that runway was rotated each week, depending on wind direction, it would mean that two weeks out of three, each community would get no night flights until 7 o’clock in the morning.
One of the key proposals in the NPS is that a noise envelope–which is essentially a set of noise performance targets applied to an area around Heathrow - will be introduced. When questioned on the noise envelope proposition, John Holland-Kaye said that it is yet to be determined how the noise envelope will work and that it would be part of the DCO process. HAL said the development of the noise envelope will be informed by the ICAO balanced approach and its noise management strategy of quieter planes, quieter operations, land use planning (including sound insulation) and operating restrictions as well as community engagement and consultation. Andrew Haines of the CAA believed that the noise envelopes should be based on high-level targets and principles:
Rather than specifying individual characteristics, you might say that, if you had a noise envelope that gave a maximum amount of noise, it might incentivise you to use more fuel-efficient planes. It might incentivise you to do work on steeper approaches. It might incentivise you to make a trade-off between engine wear and noise that is not perhaps currently incentivised.
He hoped that the concept of the noise envelope, which would be developed in coordination with the Independent Commission on Civil Aviation Noise (ICCAN), would help manage community concerns about noise:
One of the reasons we have had such difficulties with local communities is that they do not have confidence that their interests are well looked after. There are not enough incentives, and the noise envelope is a good way of demonstrating that in a transparent way.
In response to how noise performance targets will be set and enforced, the Secretary of State said that:
This is a key purpose of setting up the independent noise regulator. The enforcer remains the CAA. The noise regulator is there to say, “You have a problem that you need to fix.”
Although when questioned on the issues of enforcement, Andrew Haines said that “a lot of people think that the CAA should be enforcing on noise, and that is not our role.” In terms of penalties, the Secretary of State said that there were “a wide-ranging financial excess. We have some reasonably tough powers at our disposal. We can always toughen them further if we think it is necessary.” The Secretary of State later confirmed via correspondence that airports, rather than the CAA, are responsible for enforcing noise penalties under the Civil Aviation Act 1982.
The EAC concluded that “the NPS did not clearly lay out the nature of the legally binding noise targets.” The HSPG recommend “the NPS must set some clear parameters with regards to what this design should look like. For example, the envelope should feature the use of noise performance targets compromising of the shorter time averaging periods that are capable of assessing significant community annoyance more effectively.”
As explained by HACAN, “high quality insulation and other mitigation measures can make a significant difference to people living, working or studying under the flight path. It is particularly true for people who cannot move for reason of income, employment or other personal circumstances.” The NPS states that HAL must provide compensation to nearby residents and include financial compensation to residents who will see their homes compulsorily acquired, as well as ongoing financial compensation to the local community.
HAL has publicly committed to a community compensation package comprising offers totalling up to £2.6 billion, including an offer to pay 125% of market value, plus taxes and reasonable moving costs, for all owner-occupied homes within the compulsory acquisition zone. It has also committed to paying contributions for acoustic insulation based on a property’s location within the noise contours of an expanded airport:
It was initially not clear how HAL had proposed a fixed amount of money–the headline £2.6 billion figure–when they did not know flightpaths would be, how many people will be overflown and by what level of noise they are going to be impacted. Emma Gilthorpe clarified this, saying that the airport was not restricted to a fixed amount of money and noted it would adjust its offering based on the number of people eventually impacted.
Most submissions were supportive of compensation for nearby community, but criticised the number of people who would be eligible for noise insulation offered by HAL. This is because compensation for noise insulation will be offered based on outdated noise metrics, which are set at a higher threshold to what is recommended by best-practice noise guidance. According to the Boroughs, “the Government should be requiring Heathrow to provide enhanced levels of mitigation that reflect the findings of its latest studies.” Even then, the No Third Runway Coalition believe that “the noise mitigation package offered by Heathrow is lamentably insufficient and is not available for the majority of people who will be significantly impacted by aviation noise.” Others were critical of the per household amounts committed by HAL for noise insulation and whether it would be sufficient to offset the true costs on those affected. Stephen Clark said that “it will go nowhere near the cost of fully insulating most houses. It could cost £20,000 or £30,000 to do it.”
702 Department for Transport, , October 2017, p 52
703 C Clark, “Aircraft noise effects on health”, (University of London), May 2015
704 At the 54 dB LAeq,16hr which measures noise for a certain period of time during the day and averages that out by day over several months.
705 Schools, hospitals and religious places of worship are considered noise-sensitive buildings for the DfT appraisal.
706 Department for Transport, Appendix A, A-4 Noise, p 40
708 Department for Transport, Appendix A, A-4 Noise
709 At the 63-decibel contour level
710 Department for Transport, Appendix A, A-4 Noise, p 32
711 Department for Transport, Appendix A, A-4 Noise
712 >54 dB, >63dB, >69dB Daytime Average Noise.
715 This is an estimate of the number of people who without a runway scheme experienced noise of less than 54dB but with expansion will experience noise greater than 54dB.
716 CAA monetisation workbooks
717 The noise modelling results are only presented in the 3dB intervals, so a “worse noise” means moving from a lower interval to a higher interval.
718 CAA monetisation workbooks
719 Measured by dividing the annual number of aircraft movements by the number of people exposed to noise at the 54dB threshold of noise.
720 Department for Transport, Appendix A, A-4 Noise
721 Department for Transport, Appendix A, A-4 Noise; DfT, 2017
722 Transport for London,
723 No Third Runway Coalition ()
725 Department for Transport, Appendix A, A-4 Noise, p 8
726 Department for Transport, , February 2017
727 , October 2017, p 52
728 Metrics used by the Commission include LAeq,16h, LAeq,8h, Lnight, Lden (or LDEN), N70 and N60 metrics. The Department just used LAeq,16h and LAeq,8h. For more information about these metrics, see: Jacobs, , November 2014, p 3–5
730 Jacobs, , November 2014, p 86
731 Stephen Clark, March 2017 ()
732 Qq303–04, No Third Runway Coalition ()
734 Department for Transport, , February 2017
735 Department for Transport, , 2017
736 Stephen Clark ()
737 CAA monetisation workbooks
738 Jacobs, , November 2014, p 78
739 Jacobs, , November 2014, p 78
744 Jacobs, , November 2014
745 Department for Transport, , October 2017, p34
747 Jacobs, , November 2014; Department for Transport, Appendix A, A-4 Noise
751 Heathrow Airport Ltd ()
753 Noise modelling assumption data supplied by the CAA
754 Department for Transport, , October 2017, p 54
755 Department for Transport, , October 2017, p 29
760 London Boroughs of Hillingdon, Richmond and Wandsworth and Royal Borough of Windsor and Maidenhead, March 2017 ()
761 Environmental Audit Committee, Seventh Report of Session 2016–17, , HC 840, para 72
762 No Third Runway Coalition ()
763 Specifically, there are no scheduled departures between 11.30 pm and 6am. Arrivals start coming in at 4.30am.
764 Department for Transport, , p 54
766 Heathrow Airport Ltd, , January 2018
768 Aviation Environment Federation, March 2017, ()
770 Heathrow Airport Ltd ()
771 Q162; IAG ()
772 BAR UK ()
774 Airlines UK ()
778 Department for Transport, , October 2017, p 54
780 For more info, see: Heathrow Airport Ltd, , January 2018
786 Letter from , 23 February 2018.
787 Environmental Audit Committee, Seventh Report of Session 2016–17, , HC 840, para 86
788 Heathrow Strategic Planning Group ()
789 HACAN, March 2017 ()
790 Department for Transport , October 2017, p 82
791 Department for Transport , October 2017, p 82
793 London Boroughs of Hillingdon, Richmond and Wandsworth and Royal Borough of Windsor and Maidenhead ()
794 No Third Runway Coalition ()
Published: 23 March 2018