While the UK government is contemplating building an airport east of London, a handful of architects have already put forth their visions for an airport within the city limits, looking to the River Thames as the site of the new runways. Architecture firm Gensler imagines a future London airport set atop a series of floating platforms, allowing planes to land on top of the river without filling it with earth.
Gensler's vision for London Britannia Airport is an infrastructure project with minimal environmental impact. Four five-kilometer runways would be tethered to the river bed and floating atop the water in the Thames Estuary. The runways could be removed from the river for maintenance and additional runways could be added as needed. Similarly, the airport terminals would be constructed off-site in a shipyard and then floated in upon completion. Underwater tunnels would connect passengers to the central London and the European High Speed Rail Networks.
Gensler envisions London Britannia not as an addition to Heathrow Airport, but as its replacement. It also proposes Heathrow into an eco city, one that could house 300,000 residents. London Britannia would itself be a fairly green building, providing much of its own power through marine turbines.
But for now at least, this is just a project on paper as the government considers placing its next runways outside of London.