A group of architects and consultants has unveiled a proposal to develop a £20 billion ($32 billion), four-runway airport with twice the capacity of London Heathrow on a piece of land in the Thames estuary, as part of a wider integrated transport solution for the UK with a total price tag of £50 billion.
In addition to the proposed airport, the "Thames Hub" project would include a new flood protection barrier along with hydro-electric power stations that could harness enough energy to run the airport, and a four-track high-speed rail route that would circle London and link the airport with the north, south and west of the UK.
The airport would be capable of handling 150 million passengers a year, which those behind it believe will "enable the UK to retain its global aviation hub status". The project is the brainchild of architecture firm Foster & Partners, infrastructure consultants Halcrow and economists Volterra Partners.
Whether the Thames Estuary airport - located on the Isle of Grain, around 36mi (57km) to the east of London - is being proposed as a long-term replacement for London Heathrow remains open for discussion.
"Would Heathrow become a twin hub, would it become a specialist airport or would it close? We are leaving this question entirely open," said Huw Thomas, a partner at Foster & Partners. However, he pointed out that twin hubs "historically haven't worked", therefore, "the Thames Hub has to become the predominant airport". He added that the new airport "doesn't diminish the role of London Gatwick as a charter airport".
With Heathrow almost at full capacity and with the current government and the main opposition party having ruled out the possibility of building a third runway, Foster & Partners chairman Lord Foster believes that the UK "has to look at more strategic alternatives".
"Heathrow has a very important transitional role to play in the evolution of this as a proposal, but Heathrow is boxed in and is limited in its potential to expand," said Foster. "Whatever the future of Heathrow is, it is what it is."
Environmental concerns - both at a local and national level - have been the main drivers behind the refusal of a third runway at Heathrow. But Thomas believes that by developing an airport "with overwhelming rail connections", ground emissions could be dramatically improved. As for local level concerns: "Which is better, an approach over water or an approach over five million people? The voice of the voter is what drives politics."
Halcrow director Ben Hamer said the entire project could be delivered "by the 2020s", depending on the time it would take to secure all the necessary approvals and funding. "We are talking to central government to secure in-principle government support. How long it would take to get approval is about political debate," said Hamer. "This is about generating a debate."
The whole project would require an investment of £50 billion over 10-15 years, which "could be funded through public coffers, or fully through private investment", said Hamer, although he added that "my gut feeling is we have to present a project that can be delivered privately".
Earlier this year, London mayor Boris Johnson renewed calls to look into building a new airport on an artificial island in the Thames Estuary. The airport proposed by Foster & Partners would be built on the Isle of Grain, and is "significantly different" to what the mayor was proposing because "we are not just looking at the airport in isolation", said Foster.
Although some 50mi away from London Heathrow, the proposed airport would be only 8mi south of London Southend, immediately across the Thames Estuary.
The mayor's office could not immediately be reached for comment.