Oxford to Cambridge Expressway

Tagged with: Casework status: Open Casework type: Transport Site designations: SAC Site designations: SSSI


A major new road proposal threatens some of the most important places for nature in Oxfordshire and Buckinghamshire and will make responding to the climate and ecological emergency even more difficult.

To close a "missing link" in the strategic road network, the Government has proposed a new major road – an Expressway – to reduce journey times between Oxford and Cambridge.

The Expressway is one component of the wider proposals for the Oxford-Cambridge Arc – a “growth corridor” that aims to deliver transformational economic growth between Cambridge and Oxford, supported by new road and rail infrastructure, and up to a million new houses by 2050.

In March 2020, Highways England announced they were pausing further development of the Oxford to Cambridge expressway project to “undertake further work on other potential road projects that could support the Government’s ambition for the Oxford-Cambridge Arc”.

We welcome this announcement and the opportunity for Highways England and the Department for Transport to address the concerns we have raised about the potentially damaging environmental impacts of the Expressway.

A preferred corridor was announced in autumn 2018, running west from the M1 at Milton Keynes, south of Bletchley, and then widening out to encompass a broad swathe of land across central Buckinghamshire. The corridor allowed for a northern or southern route around Oxford connecting with the A34. Thankfully, the Government recognised the importance of the Otmoor basin for nature – including our own nature reserve – and excluded any part of that area from further consideration. However, the rest of the corridor still includes two internationally important sites and over thirty Sites of Special Scientific Interest, or "SSSIs", and even locally important sites including rare hay meadows and ancient woodlands, some of them managed by our partners in the Wildlife Trusts. So even though the direct threat to Otmoor has been lifted, this could be a road to disaster for nature and help push us towards dangerous levels of climate change.

Picture credit: Bittern by Paul Wyeth


Why is it worth fighting for?

We are pleased that the direct threat to Otmoor and the immediate surrounding landscape has been lifted. This means the wetland wonderland of Otmoor, which once inspired Lewis Carroll to write "Alice Through the Looking Glass", will be preserved for future generations, though we still need to understand and deal with any indirect effects from the road or associated urban growth, especially any proposals upstream of Otmoor in the Upper Ray Valley.

However, numerous other homes for nature are still threatened. Highways England's own assessment of the different corridor options rated parts of the preferred corridor as “highly” or “moderately disadvantageous” for the environment, including impacts on protected sites.

The reason for Highways England's assessment are obvious. Beyond Otmoor, the area affected by the Expressway has some wonderful homes for nature, including:

  • Two internationally important sites south-west of Oxford named Cothill Fen, and Oxford Meadows. These are important for rare plant communities and highly vulnerable to air and water pollution, changes to groundwater, and to surface flooding patterns.
  • Over 30 SSSIs, especially large ancient woodland SSSIs in the wider landscape known as Bernwood Forest in Buckinghamshire east of the M40. These sites are precious for their woodland butterflies and bats and include breeding sites for one of Britain’s rarest mammals - Bechstein's bats.
  • The upper Ray Valley, home to nationally rare and declining species like breeding curlews and black hairstreak butterflies. Our partners, Berkshire, Buckinghamshire and Oxfordshire Wildlife Trust (BBOWT), manage an important group of lowland meadows there rich in wildflowers and herbs: a habitat almost gone from much of England. 
  • Right where East-West Rail and High Speed 2 intersect lies Calvert Jubilee, another BBOWT nature reserve important for breeding and wintering birds including bitterns, and declining butterflies like grizzled skippers.

Further east still lies the Greensand Ridge, an area of higher ground covered with woodlands and heathlands, home also to Woburn Park. Here is another cluster of SSSIs and locally designated wildlife sites.

Curlew Numenius arquata, bathing in shallow pool, Geltsdale RSPB reserve, Cumbria, England

Our position

Otmoor is important to us and as you would expect, we're glad it is safe, at least from any direct impacts of the road and associated urban growth. But our position on the Expressway has always reflected the bigger picture, looking at the larger landscape areas that are richest in important sites, habitats and species.

Notwithstanding Highways England’s announcement in March 2020 that they were pausing work to develop the Oxford to Cambridge expressway project, our three main concerns about this road are:

For nature, Highways England’s preferred corridor for the Expressway is the worst for nature

  • Compared to the alternatives that have now been taken off the table, the preferred corridor has the highest number and density of wildlife sites. Some of them carry the highest levels of legal protection, as SSSIs and as internationally important wildlife sites. Any route in this corridor therefore makes it much harder for Highways England to avoid direct or indirect damage and achieve even their own rather weak objective of ensuring “no net loss” of biodiversity (at a time when the Government is pressing other developers to deliver 10% net gain in biodiversity through their proposals).

Worse still, Highways England avoided any proper consideration of the relative wildlife value of the alternative corridors when the preferred choice was made, instead making the irresponsible assumption that any damage could simply be offset (i.e. compensated for). That’s not as easy as Highways England seem to think, and in the case of irreplaceable habitats like ancient woodland full compensation is widely seen as impossible. The reality is that we will probably see even more loss of biodiversity in a region which is already one of the most nature-depleted in the UK, whatever clever accounting system for loss and gain in biodiversity is applied on paper.

  • A major road like this takes a lot of land, so direct loss of habitat could be a major threat. When high road noise levels are introduced to formerly quiet landscapes, research shows the diversity and numbers of breeding birds are often reduced. And because of their width and high traffic volumes and speeds, such roads often form a serious barrier to the movement of many animals especially if solid “Jersey barrier” central dividers are used. Vehicles kill many animals and for some, this can become a threat to their local populations – barn owls and hedgehogs are good examples. Air and water quality can suffer locally as well, with insidious effects on semi-natural habitats like lowland meadows, rivers and streams through deposition of chemicals like nitrogen.
  • The Intergovernmental Panel on Biodiversity and Ecosystem Services found that globally 1 million species are at risk of extinction. The 2019 State of Nature report identifies that nationally 15% of wildlife species are at risk of extinction. Economic and infrastructure development has the ability to contribute to nature’s recovery through a biodiversity net gain approach, but at present the Expressway proposals seem destined to make a bad situation even worse.


There has not been a joined-up approach to planning for strategic transport infrastructure (the Expressway and East West Rail) together with housing

This is not just about a new road. The choice of preferred corridor was clearly based on its alignment with East West Rail (already at an advanced stage of delivery in this part of the Oxford to Cambridge Corridor), and the shared potential the Government says this offers to support major new settlements and urban growth. New settlements will bring their own challenges – direct land take and loss of locally important habitats, and likely indirect effects including impacts on air quality, on water resources that are already over-exploited in places, and from increased recreational pressure in fragmented and isolated wildlife habitats. The connection between the road and urban growth has been made loud and clear by the Government and yet they have refused to adopt a joined-up approach to considering the full, combined environmental impacts or to consider the range of alternative approaches that could be followed. The Berkshire, Buckinghamshire and Oxfordshire Wildlife Trust (BBOWT) mounted a legal challenge to the Government’s failure to apply Strategic Environmental Assessment (SEA) to the Expressway corridor selection in 2018/19, supported by evidence from the RSPB, but lost the case.

It is not clear how building a major new road is consistent with reducing greenhouse gas emissions

Climate change is the biggest threat to nature and our own way of life. The speed and scale of climate change is widely recognised in scientific and environmental circles. We have to act fast or we will face increasing disruption and chaos including, ironically, to our own ability to travel safely and reliably. In May 2019 the UK Government declared a “climate emergency”, having already committed to achieving carbon neutrality by 2050.

The Intergovernmental Panel on Climate Change (IPCC) found that we must reduce global carbon output by 45% by 2030 to limit global warming to 1.5°C. Huge reductions in carbon emissions are needed in all sectors, including transport.

The Department for Transport (DfT) is preparing the UK's first Transport Decarbonisation Plan, which will set out a programme to ensure carbon neutrality by 2050. While this is a step forward, the deadline of 2050 does not match the urgency of the climate and ecological crises we face: alongside partner organisations we are calling for more urgent action to achieve a zero-carbon transport sector by 2045, if not sooner - in line with the IPCC’s warning.

More locally, in autumn 2019 the England’s Economic Heartland (EEH) group* consulted on an outline Transport Strategy for consultation that sets out a welcome ambition for the transport sector to become zero carbon by 2050 (though again we think this timescale is too leisurely). In our shared response with the Wildlife Trusts we have called on the EEH to say more about how the Expressway fits with the urgent need to reduce transport-based carbon emissions. Even the furthest target date of 2050 is only thirty years away there’s no time to waste: the choices made from today onwards need to move us in the right direction, not take us in the wrong one.

The RSPB is working with partner organisations including BBOWT, the Woodland Trust and others to compile our responses, with the aim of reflecting a shared view as much as we can. The details will be developed once we have fully understood the proposals and assessed their impacts on wildlife sites and vulnerable species but our response is likely to be structured around the three main concerns highlighted above (impact on nature, lack of joined-up planning for transport, housing and infrastructure, and the conflict with targets to reduce greenhouse gas emissions). 

*EEH is a sub-national transport body covering the Oxford-Cambridge growth corridor counties of Oxon, Bucks, Northants, Beds and Cambs, as well as Herts.

How you can help

In March 2020, Highways England announced the development of the Expressway proposals was being paused to “undertake further work on other potential road projects that could support the Government’s ambition for the Oxford-Cambridge Arc”.

We will be scrutinising the next steps taken by Government in relation to the Expressway proposals and any alternative potential road projects, so keep an eye on this page for updates.

In the meantime, if you are keen for your voice to be heard, the RSPB recommends writing to your MP. You could also write to Grant Shapps MP, who is currently the Secretary of State for Transport.

Here are a few over-arching things you could consider mentioning to your MP or the Secretary of State. Refer to our full response to the previous consultation (in 2018) under the downloads tab for more detail, and do please take the time to make these points in your own words:

  • That Strategic Environmental Assessment* ("SEA") of the route options should be carried out as a matter of urgent priority, to ensure that less environmentally damaging options are not excluded from consideration;
  • That Highways England should select a preferred route that best avoids and minimises impacts on nature – particularly, nationally and internationally important protected sites;
  • That they should also set themselves an objective of achieving biodiversity net gain, not merely one of no net loss, as at present;
  • That the choice of preferred route must account for all likely urban growth scenarios, not just development already in Local Plans. The latter represents only a small part of what the Government intends for the Oxford-Cambridge corridor;
  • That a major new road is unlikely to be compatible with the UK’s legal obligation to reduce carbon emissions to net zero by 2050, needed to urgently address the climate emergency. The Department for Transport must demonstrate how the new road proposals for the Arc would help decarbonise the transport sector and support the UK’s net zero 2050 target.

*If you’re confused about SEA and EIA (Environmental Impact Assessment) it's worth knowing that EIA will be done once the preferred route is chosen and the designs have been well worked up – but by then, different and potentially less damaging alternatives may have been dropped from further consideration. Doing SEA of all the options beforehand would help ensure the best overall choice of solution is made before options are narrowed down and proposals are worked up in full detail. For more information visit the government's guidance page here.


  • March 2020
    Government announces a pause to further development work on the Expressway, apparently to consider other options to support their aspirations for the Growth Arc.
  • Autumn 2019
    Highways England plan to consult stakeholders and local communities about route options within Corridor B, ahead of choosing a preferred route.
  • September 2018
    The Government announced its preferred corridor, B, but excluded sub-option B2 which included parts of Otmoor. 
  • August 2018
    The RSPB endorsed a letter written on behalf of the Horton-cum-Studley Expressway Group by the Environmental Law Foundation, addressed to the Secretary of State for Transport and to Highways England. The letter asked for an explanation for why Strategic Environmental Assessment hasn’t been done.
  • April 2018
    The RSPB’s response on the corridor options is submitted.
  • February 2018
    After a second meeting of the SRG, Highways England consults the RSPB and other environmental stakeholders on the corridor options.
  • December 2017
    Highways England creates the Strategic Environment Stakeholder Reference Group (SRG) for the Expressway and invites the RSPB to participate.
  • November 2017
    The Chancellor’s autumn budget statement announces 1M new homes to be built in the Oxford to Cambridge Arc.