Preliminary Environmental Impact Report response

East Sussex County Council response to the proposed Gatwick Northern Runway Project (consultation on the PEIR)

1 December 2021

Thank you for the opportunity to provide comments on the Preliminary Environmental Information Report (PEIR).  This is an East Sussex County Council (ESCC) officer response to the evidence presented by Gatwick Airport Limited in the PEIR supporting the proposed northern runway project.

The matters covered by the PEIR that are of greatest concern to ESCC are as follows:

  • Aviation forecasts and the baseline scenario estimates
  • Surface Access, Traffic and Transport
  • Carbon Emissions and Climate Change
  • Overflight: Increase in flights over local communities
  • Noise impacts
  • Health and Wellbeing

Aviation forecasts and the baseline scenario estimates

Below is a summary of the key points raised in the report provided by York Aviation. For the full report by York Aviation please see Appendix 1 (attached).

Initial comment regarding the lack of detailed information

Insufficient information has been provided to enable the basis of its demand forecasts, and how these relate to the capacity that may be provided through the simultaneous use of the Northern Runway, to be properly understood in adequate detail for the local authorities to be able to comment on the impact of the proposals. 

York Aviation – who have been appointed by the local authorities around Gatwick to support their assessment of elements of the PEIR - requested further information from GAL regarding the basis of the demand forecasts and the assessment of capacity with and without development, but this has not been forthcoming.

The Need Case

The Need Case, as currently set out, is very generic, relying on general Government statements about shortage of airport capacity and the benefits of expansion, including airports making best use of their existing runways.  It also relies on Gatwick being virtually full prior to the pandemic and the implications that had for resilience and delays. 

Although none of these points are disputed, the consultation documents, in particular the sections on the capacity with and without development and on the demand forecasts, lack sufficient cogent detail to validate the Need Case.  This will need to be addressed before submission and, to the extent that the validation of capacity with and without development and the demand forecasts underpin the assessment of impacts, will require further explanation to ensure that the impacts of development are properly understood and assessed.  It seems to us imperative that GAL engages on these topics as a matter of urgency so that the impact assessments within the PEIR can be appropriately validated.

Capacity Assessments and demand

In the material presented by GAL, there is a lack of information or detail on how capacity has been assessed and validated across the airfield as a whole.  This is essential before considering whether the demand projections are a robust basis for the assessment of impacts as, if capacity is less in either case, throughput may be constrained in both the Baseline and ‘With Development’ cases to lower than assessed.  The Baseline forecast is presented as a capacity constrained forecast so verifying the level of this constraint is key.  The ‘With Development’ forecast appears to be unconstrained and assumes that the capacity delivered by the proposals will be sufficient to meet demand. 

The future baseline forecasts (without the project)

In the absence of further information, we are concerned that GAL has put forward a Baseline case that may be undeliverable, particularly in relation to the assumed increase in runway movement rate on a single runway, and this potentially undermines the validity of the assessment of the effects of the development if the Baseline is set too high. 

Further technical discussion is required to understand how the Baseline capacity would be delivered.  It is also not clear if the works required to support the Baseline would require planning permission and so are, in effect, part of the project.

Capacity (hourly movements)

In terms of the proposed development itself and based on our understanding of the applicable rules for the operation of parallel runways separated only by 210m, GAL has not demonstrated that 70 movements per hour is attainable through using the Northern Runway, which has implications for the validity of the forecasts With Development.  A detailed technical discussion with GAL would be required to understand how it is intended that the increased capacity is to be achieved. 

If the increase in hourly movements is not achievable then the assessed impacts, positive and negative, will have been wrongly stated. Based on our current assessment of the information provided, we would not be confident that either the Baseline or ‘With Development’ capacities have been robustly assessed.

Demand Forecasts

The demand forecasts are set out in Appendix 4.3.1 to the PEIR: Forecast Data Book.  Although some information is provided on current operations at the Airport and some greater explanation about the characteristics of demand and its profile in the Baseline Case, there is limited explanation provided as to the basis upon which the projections of future demand have been made. Except in relation to fleet mix, there does not appear to be any sensitivity analysis considering different growth trajectories and we strongly suggest that this additional analysis needs to be undertaken.

Forecasts, Heathrow third runway and other airports increasing capacity

We are concerned that the forecasts as presented do not take into account the likely provision of a third runway at Heathrow at some point in the 2030s as this remains Government policy and airports seeking to make best use of their existing runways are required to demonstrate a need distinct from and not being met by the third runway at Heathrow.  The forecast assessment has not taken this into account and also does not consider the prospect of other airports increasing their capacity, including the increase already consented at Stansted. 

At the very least, these potential increases in capacity elsewhere should have been subject to sensitivity analyses.

Forecasting methodology

Overall, the methodology by which the forecasts have been produced is simply not set out.  Hence, this substantially limits the reliance that can be placed on them.  This is material to all of the assessments made that rely on the demand forecasts. Furthermore, it is not apparent to us that any account has been taken of the cost of carbon and future abatement measures in the forecasts which makes them inconsistent with the Government’s Jet Zero policy.

To the extent that the projected increases in airport capacity, particularly the runway movement rate cannot be delivered, the forecasts would need to be reduced accordingly.  Because the relationship between the hourly increase in capacity and how this relates to the annual demand forecasts has not been clearly set out, it is not clear how this has been taken into account. 

Based on the information presented, we have some concerns about the consistency of the assumptions used to derive specific outputs for assessment, in particular the assumption of the reduced seasonality of demand, the daily profile of demand relative to the use of the runways and the optimisation of aircraft departure routes.  Further detailed explanation is required so that the realism of the forecasts and the assessments deriving from them can be verified.

Future airspace change

Whilst the proposal to make simultaneous use of the northern runway will not require airspace change, realising the overall growth in aircraft movements envisaged, particularly when growth in activity at other airports across the South of England is taken into account, will necessitate some changes to airspace in the vicinity of Gatwick as part of the modernisation process. 

Although the effect of these changes cannot currently be assessed as part of the DCO application, GAL should acknowledge this overall dependency in order not to mislead the public. 

Airport layout

Whilst it is commendable that the proposed facilities for the expanded airport can be largely contained within the existing airport footprint, the resulting airport layout is complex and, potentially, inefficient in operation, leading to increased delays.  This could result in airlines being less willing to grow their operations at Gatwick than implied by the demand forecasts due to increased operating costs.

Fleet mix

We consider that the fleet mix assumed in the Central Case for assessment is somewhat optimistic, particularly in the early years given the deferral of aircraft orders that has occurred during the pandemic, but that the Slower Transition Case represents a robust worst case.  However, this comment needs to be caveated by the confusion regarding which aircraft mix has actually been assessed as two different fleet mixes are presented in the PEIR.

UK level assessment of the economic impact

The evidence base relies heavily on the UK level assessment of the economic impact of the proposal in its Need Case, citing at para. 1.19 of the Overview Consultation Document that the benefits are greater than those assessed for Crossrail.  Whilst our analysis would suggest the assessment is generally technically robust, there may be areas where the assessment may have been under or over-stated.  Nonetheless, a fundamental concern is in relation to the demand forecasts and the risk that demand growth may be slower than expected so impacting on the discounting of benefits, which could be overstated relative to the costs to some degree. 

The local economic impact assessment

Overall, in our view, the local economic impact assessment presents a robust estimate of the economic footprint of the development, with a reasonable estimate of the direct effects, including employment.  Again, however, it should be noted that the estimates are fundamentally reliant on the traffic forecasts put forward.  If the build-up of these forecasts is different, then the point in time at which economic footprint effects are delivered will be different.  However, it should be noted that the consequences for the overall scale of these impacts is unlikely to be significant assuming that the same total passenger throughput can be attained over the longer term.  The assessment of local impacts concludes that the proposed development will have a substantial impact on local economies in both gross (economic footprint) and net assessment terms.  The approach used appears sound and we have only relatively limited comments at this stage and some suggestions as to where improvements might be made or further investigation undertaken.  Where we have significant concerns, these do not relate to the approach to the economic impact assessment as such, but to the traffic forecasts that feed the assessment.

Surface Access, Traffic and Transport

Public Transport

Whilst the airport is accessible by rail from the coastal areas of the county, at present the public transport options between the central and northern parts of East Sussex and Gatwick are very limited.  Therefore the majority of journeys especially from this part of the county are made by car.

It is vital that Gatwick Airport honour their commitment to maximise the opportunities for public transport for passenger and staff travel as part of their northern runway proposals and we would want to see new bus services provided to the central and northern parts of East Sussex as part of the mitigation package should the northern runway proposal come forward.

This is especially important with the Government’s focus on improving public transport provision through their Bus Back Better strategy published in March 2021 and latterly with the approval and submission to Government of our Bus Service Improvement Plan in October 2021.  Improved bus connectivity between the north of the county and the Airport will build on our already ambitious plans to improve bus services within East Sussex by enabling longer distance inter-urban journeys to be undertaken by public transport rather than by car.


The PEIR indicates that, from a highways perspective, the construction and operation of the northern runway is not expected to have significant effects beyond the immediate local highways around the airport (M23 and A23 in Crawley) when compared to the baseline forecast.  As a consequence, the PEIR highlighted that the increased capacity provided by the introduction of the smart motorway on the M23 between junctions 8 and 10 in 2020 and the proposed package of highway measures focused on the junctions near the airport will mitigate any impacts derived from operating the northern runway.

Whilst these improvements are welcomed, there is a need to also address the ever-growing problem of approaching traffic from the surrounding road network, including routes in East Sussex such as the A22 and A264, which feed into the A23/M23 corridor.  Therefore, further consideration should be undertaken ahead of the DCO application stage with the local highway authorities on to the impacts of airport growth on their respective highway networks beyond the immediate environs of the airport.

Carbon Emissions and Climate Change

Please refer to the AECOM report ‘Climate Change and Carbon Response Report’ in Appendix 3 for full details of the technical review, in response to the PEIR consultation (Chapter 15, Climate Change and Carbon). The following key points provide an overview of the main issues from the AECOM report from an East Sussex perspective:

Lack of detail on identified Green House Gas (GHG) mitigation

Due to the lack of detail on identified Green House Gas (GHG) mitigation we have been unable to determine the full impact of the proposed scheme on the climate. The GHG footprint presented in the PEIR is considerable and it is important for everyone to be able to understand how emissions will be mitigated.

While it is acknowledged that at the PEIR stage there are still uncertainties around design, it would be reasonable to have expected to see more on mitigation at this stage. We therefore request that detailed mitigation is set out at the DCO application stage in line with latest policy (e.g. Jet Zero).

Lack of detail on identified Climate Change Resilience (CCR) mitigation

Due to the lack of detail on identified CCR mitigation we have been unable to fully assess the climate change resilience of the NRP. We therefore ask that detailed mitigation measures are provided at the DCO application stage or before.

Lack of detail on identified ‘In-Combination Climate Change Impacts’ (ICCCI) mitigation

Due to the lack of detail on identified in-combination climate change impact mitigation we have been unable to fully assess whether there are any significant ICCCI. We therefore ask that detailed mitigation measures are provided at the DCO application stage or before.

Other feedback

For each of the three assessment (GHG, CCR and ICCCI) AECOM have also made a number of comments and recommendations regarding the following points which need to be addressed at DCO application stage or before:

  • Baseline, methodology and assessment issues
  • Mitigation and Commitments
  • Construction and Operational impacts on LAs
  • Outlook on policy/legislation compliance
  • Data Gaps and/or inconsistencies

Overflight: Assessing the increase in flights over local communities

Due to the effects of overflight and noise disturbance on people’s health and wellbeing, it is very important for us to gain an accurate understanding of how many more flights would be passing over East Sussex and which locations would be the most affected.

We are concerned that there is currently insufficient detail in the PEIR regarding the increase in flights passing over East Sussex. We are also concerned about the accuracy and reliability of the estimated overflight mapping.

Online map tool

Our understanding, based on the Noise Topic Working Groups, is that GAL are planning to provide an online map tool (18,000 post codes) which will enable people living further from the airport (up to 35 miles) to look up the change in the numbers of overflights expected. We were unable to find any reference to this in the PEIR. It would be useful if GAL could confirm that the online map tool is still going ahead, the full geographical extent and advise whether or not it will be provided before the submission of the DCO.

Because the PEIR hasn’t made any reference to the online map tool, we don’t have any indication as to what level of detail/accuracy will be provided.

Overflight maps in the PEIR

The following overflight maps are included in the PEIR:

Figure 14.6.7 – 2018 Baseline Gatwick Overflights

Figure 14.6.8 – 2018 Baseline Non-Gatwick Overflights

Figure 14.6.9 – 2018 Baseline All Airport Overflights

Figure 14.9.28 – 2032 Departure Overflights from the Main and Northern Runways

Figure 14.9.29 – All Airport Overflights with Project Flights (20%)

Our comments on the overflight maps are as follows:

  • As things currently stand the only way to assess the projected increase in overflights is to put the two plans next to each other (Fig 14.6.9 the 2018 baseline map and Fig. 14.9.29 ‘All Airport Overflights with Project Flights’) and make a visual comparison between the two plans.
  • The overflight mapping is lacking in specific detail. Regarding the legend and the scale used for the overflight figures, a very broad range is used i.e. Orange represents 100-200 overflights. This is not enough a fine enough grain of detail for us to gain an understanding of how many additional overflights there will be with the NRP.
  • The scale of the overflight maps and the resolution of the PDF files makes it difficult to assess.
  • To give a better indication of how overflight is expected to change, information should be provided for different months of the year. It should also show any difference between mid-week and weekend periods. For example it should be possible to see overflight information for mid-week and weekends in the winter (2018), which can be compared with mid-week and weekends in winter ‘with project’.
  • Is it too simplistic an approach to just add 20% to the 2018 overflight data?

Figure 14.9.28 (2032 Departure Overflights from the Main and Northern Runways)

This doesn’t cover any areas of East Sussex – we would strongly suggest that this information is provided unless clarification can be provided as to whether the altitude of flights are above 7,000ft by the time they fly over East Sussex.

Noise impacts

Please refer to the AECOM report ‘Noise and Vibration Report’ in Appendix 4 for full details of the technical review, in response to the PEIR consultation (Chapter 14, Noise and Vibration).

The following key points (data gaps and/or inconsistencies) provide an overview of the main issues from the AECOM report:

  • Baseline noise data from 2016 survey is not presented.
  • Information on aircraft fleets, movement numbers and track usage for the assessment scenarios are not provided.
  • No noise data from the Gatwick Airport Noise and Track Keeping system is presented in the PEIR.
  • There is a lack of detail on the noise modelling methodology and validation using data from the Noise and Track Keeping system.
  • No details on weather conditions applied in noise modelling are provided.
  • Overflights are presented in a 3.6x3.6km grid, so not considered to be of sufficient resolution for any meaningful analysis.

No air noise assessments for anywhere in East Sussex (comment from ESCC Officers)

Air noise relates to noise from aircraft in the air, or departing or arriving on a runway, generally assessed to a height up to 7,000 feet above ground level. We understand that some aircraft (Gatwick related air traffic) do pass over parts of East Sussex below 7,000 feet and therefore we ask whether the affected areas should be part of the air noise modelling work.

Withyham Noise Monitoring Location

Given that there is a permanent live noise monitoring station in Withyham, we would have expected this location to have been covered by noise modelling in the PEIR.

Health and Wellbeing

We await comments from Public Healt 


APPENDIX 1:  SEE ATTACHMENT - Full report from York Aviation


APPENDIX 2:  SEE ATTACHMENT –Traffic & Transport: full report from AECOM


APPENDIX 3: SEE ATTACHMENT –Climate Change and Carbon: full report from AECOM


APPENDIX 4: SEE ATTACHMENT – Noise: full report from AECOM