The Experts’ View: Prof F. Eigenbrod, Dr M. Hudson, Dr P Shaw, Dr J.G. Dyke, Prof C. Heady

Response to the Environmental Impact Assessment (EIA) of the proposed runway expansion of Southampton International Airport

Prof F. Eigenbrod, Dr M. Hudson, Dr P Shaw, Dr J.G. Dyke, Prof C. Heady Corresponding address:

December 4th, 2019
The proposed extension of Southampton Airport runway and increase of annual passenger numbers to 3 million by 2021 and to 5 million by 2037 will significantly increase climate, noise, and air pollution. These impacts go significantly beyond those originally assumed by the original Master Plan. The Environmental Impact Assessment (EIA) produced by Savills for the proposed extension significantly underestimates the negative impacts of the airport. Indeed, the EIA does not appear to meet its legal obligation to consider the maximum adverse effects of the expansion (the so-called ‘Rochdale Envelope established in case law ( ) both in the case of the noise impact of the airport and in the case of the increased traffic the airport will create. Moreover, the EIA understates the climate change impact of the airport expansion; which is approximately the same as adding an additional city of 100,00 people. The projected economic benefits of the expansion are also grossly inflated, as they are based on the unrealistic assumptions, and excludes factors such as the negative impact on house prices that the increased noise will incur, as well as the losses of productivity resulting in increased traffic congestion near the airport. As such, it is clear that the case made in the EIA that the benefits of expansion exceed the negative impacts is simply incorrect – the proposed expansion will have severe, long-term impacts on climate and noise pollution, create unmanageable levels of traffic congestion, therefore greatly outweighing any economic effects.
Details on 1) noise and population health; 2) transport and access; 3) climate change impacts; and 4) economic benefits are outlined below.

The effects of plane noise on local residents are addressed in two chapters in the EIA – Chapter 11 (Noise and Vibration) and Chapter 15 (Population Health). In Chapter 15, the EIA clearly lays out current policy:

The EIA (in Chapter 15) goes on to point out that the maximum level of airplane noise is recommended by the WHO is 45 dB The specific WHO guidance ‘strongly recommends’ keeping airport noise below 45 dB, as levels above this are associated with ‘adverse health outcomes’; however Chapter 15 dismisses the 45dB threshold as not being relevant as ‘these are recommendations not requirements’.
The EIA (Chapter 15) also outlines the UK’s Aviation Policy Framework, which also publishes what it considers maximum noise standards – these are 51dB during the day and 45dB during the night (below):

However, the actual modelling of the potential population affected by the proposed expansion (carried out in Chapter 11) only models daytime noise contours at 54dB and above, not the 51 dB suggested by the Aviation Policy Framework (APF) or the 45 dB recommended by the WHO. Indeed, while Chapter 11 refers to the APF, it makes no mention of the recommendation to keep daytime noise below 51 dB. This is a startling omission as is clearly stated in Chapter 15! Indeed, Chapter 11 suggests there is very little evidence as to what the Lowest Observable Adverse Effect Level (LOAEL) actually is, again apparently ignoring Chapter 15.
Given the well -documented potential negative health of aircraft noise, only modelling effects starting at 54dB is clearly inadequate and contrary to the legal obligation to meet the Rochdale Envelope principle of considering the maximum adverse effects of the proposed expansion.
Chapter 11 makes it clear that the proposed runway extension will lead to very large increases in the number of people affected by noise at the 54, 57 and 63 dB contour noise contours. Therefore, it is likely that considering 51 dB or 45 dB contours would mean a very substantial fraction of the population and Eastleigh and Southampton would be adversely affected by airplane noise resulting from the proposed extension. Note that 54 dB is nearly twice as high as 45 dB, as dB is measured on the log scale.
Moreover, Chapter 11 of the EIA admits (11.6.14) that the:
“sensitivity of the receptors [i.e. people], both households and [Bitterne Park Secondary’] school, is considered to be high, and the magnitude of the impact, is considered to be high. Therefore, there is likely to be a direct, long-term, adverse effect of major significance, prior to the implementation of mitigation measures.” (our emphasis).
Crucially, the population affected by noise in 2037 at 63 dB or above (so 1.5 times as high as the maximum noise standard in the EIA, and the level at which the major impact applies, according to the EIA) is a significant underestimate (1550 people) as it fails to consider the student population of Bitterne Park Secondary school (1752 – ). Moreover, the proposed mitigation measure of noise insulating windows (which will be provided by the airport) for Bitterne Park Secondary school and other residents who will be within the 63 dB noise contour by 2021 or 2037, will be largely ineffective during summer days (when noise levels are predicted to be highest by the EIA). This is because neither the school nor most residents have air conditioning, so clearly this insulation will be much less effective in the summer months as people will need to open windows to stay cool. The WHO report on aircraft noise (link above) points out (Page 69) that numerous studies have shown strong links between aircraft noise and reading and oral comprehension in children. As such, it is clear – even from the very limited assessment in Chapter 11 – that the proposed expansion will have a “direct, long-term adverse effect of major significance” for over 3300 people – the 1550 residents, and the 1750 students, plus staff, at Bitterne Park school – even after mitigation measures are carried out.

Transport and access
Chapter 8 ( ‘Transport and Access’) of the EIA, only considers increased traffic due to the airport for 3 million passengers, not the 5 million the airport forecasts by 2037. This is because (in the EIA’s own words) “the supporting infrastructure” limits growth to 3 million passengers a year:

However, “Environmental Statement Appendix 6.1 – The Economic Impact Assessment”, clearly states that the projected maximum annual benefits of £400 million in benefits by 2037 will only occur due to the 5 million passengers a year associated with the MasterPlan (enabled by the runway extension). Moreover, most other effects of the airport expansion (noise, emissions, DO consider the 5 million passengers. Again, the Rochdale Envelope approach makes it clear that the EIA should be made within certain bounds, and consistently applied; this is clearly not the case here.
As such, the EIA is once again importantly flawed and has not met its obligation to outline the maximum adverse affects of the proposed expansion in terms of its consideration of the potentially very large impacts on road traffic.

Furthermore, the transport assessment (Chapter 8) only considers percentage increases in traffic on roads associated with an increase from 2 to 3 million passengers, and not the effects these increases will actually have on journey times. As congestion near the airport on the M27 and the key surface roads near the airport and Junction 5 is already a major issue, it is highly likely that even small percentage increases (e.g. 1%) will have cumulative impacts on journey times much greater than 1% even for 3 million passengers, as most roads are already near capacity. Of course, the impact of 5 million passengers on road traffic will clearly will be much greater.

The climate impacts produced by Southampton Airport from the aircraft using the airport is estimated to be 998 thousand tons of CO2 equivalent in 2021 (this includes taxing, take off, landing, climbing, cruising, and descent). Total emissions for the Eastleigh area for 2021 (minus aviation) are projected to be 609 thousand tons of CO2 equivalent.
The significant increase in carbon emissions from Southampton Airport is incompatible with the emerging local plan.
13.2.14 In addition, the local plan notes the need to “limit emissions of carbon dioxide and other greenhouse gases from existing and new development, transport and other activity in the Borough, make sure that new development does not worsen climate change or suffer from its effects, including flooding, and find ways of mitigating and adapting to climate change”.
13.2.15 Eastleigh Borough Council’s Climate Change Strategy details Eastleigh’s vision for tackling climate change within the borough, in particular Eastleigh Borough Councils’ desire to “be regarded nationally as a leader in how to tackle climate”. The strategy covers eight areas, including transport, low carbon development and construction and adapting to climate change. The strategy does not include any specifics regarding the Southampton International Airport or aviation. However, it does propose that “All significant new developments will be built to high economically, socially and environmentally sustainable standards”.
The proposed extension will lead to Southampton Airport producing carbon emissions 160% greater than those produced within the Eastleigh region by 2021. Moreover, during the Fifth Carbon Budget (2028-2032), the 0.14% of emissions accounted for by the proposed extension (Table 13.9) is equivalent to the carbon budget of 98,000 people (assuming a population of 70 million in the UK during this time period). The magnitude of these climate impacts threaten to dwarf any climate mitigation efforts by Eastleigh Borough County Council.

Economic Impact
The EIA economic assessment (Appendix 6.1 – The Economic Impact Assessment”) is carried out by Steer Davies Gleave. It states that the projected maximum annual benefits of £400 million in benefits by 2037 due to the 5 million passengers a year associated with the MasterPlan (enabled by the runway extension). It is important to note that the economic benefits of ‘business as usual’ (so NO runway extension) are assumed to be £275 million a year, based on 3.3 million passengers/year associated with an increase to 3.3 million passengers – which is possible without the runway extension – so the maximum net effect of the expansion is (based on this modelling) £125 million a year, and not £400 million. Similarly, the maximum net effect on employment is 1450 additional jobs by 2037, when compared to no expansion. However, in both cases, the EIA assumes a linear
increase in economic and employment benefits with passenger numbers. This is wrong – the economic forecasts should be based on modelling the marginal increase of increasing passenger numbers to an existing airport, not treating the effects of the extra 3 million passengers as it was a new airport in a region with no airport (which is what the linear extrapolation in benefits assumes). This is because there is clearly a much larger increase in economic benefits to going from no airport to regional airport like Southampton, then increasing existing passenger numbers on an existing airport. Similarly, the economics of scale mean that increasingly less people are needed to do a given amount of work as the size of a given enterprise increases – it will not take twice as many people to run an airport with twice as many passengers.

Moreover, at present (according to the EIA), only 32% of the indirect economic impact of the airport occurs within the Solent region. As indirect impacts are projected to account for £49.5 million of the £125 million benefit of the expansion, this reduces the positive impact of the affected area to a maximum £109 million a year. In addition, the projected maximum effect on economic activity of £109 million (based on the erroneous linear increase assumption) ignores the negative economic impacts associated with reductions in house prices (due to the greatly increased noise near the airport) nor in the losses in productivity associated with traffic congestion induced by the expansion. Indeed, it is impossible to tell from the economic analysis if the net economic effect of the airport is indeed more likely to be positive, or – after accounting for negative effects of lost productivity due to traffic congestion, a fall in house prices, and the erroneous assumption of a linear increase in benefits – it is actually negative.
Finally, even the widely optimistic £109 million in benefits would only entail a small increase to the local economy. The GVA (total economic activity; of Southampton was approximately £5.8 billion in 2015; for Eastleigh it is £3.6 billion (£9.4 billion in total) – so the yearly economic benefit is at best 1.1% of the total economic activity just in these two cities in 2015 (not including Portsmouth); clearly, the relative contribution will only decrease as the economies of both cities grow.
The estimates of the impacts of the expansion on jobs are similarly inflated, as the off-airport jobs are based on the flawed economic projections of a continued linear increase in benefits. It is also very likely that the projected increase in jobs at the airport is an overestimate. This is because in the 2006, the airport masterplan claimed that by 2015 Southampton Airport would employ 1541 people. However, according to the EIA, the airport only employs 950 people at present (58% of the projection), with a projection of 1500 jobs at the airport in 2037. If the new forecast is a similar overestimate, there may only be minimal new jobs at the airport by 2037.

About us
Prof Felix Eigenbrod is a geographer and Professor of Applied Spatial Ecology at the University of Southampton.
Dr Malcolm Hudson is an Associate Professor in Environmental Sciences at the University of Southampton, and an expert on Environmental Impact Assessments.
Dr Peter Shaw is an Associate Professor in Environmental Sciences at the University of Southampton, and an expert on applied Environmental Science.
Dr James Dyke is a geographer and Senior Lecturer in Global Systems at the University of Exeter.
Prof Christopher Heady is a Professor of Economics at the University of Kent

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