London could have a new airport built on a man-made island in the Thames estuary east of London by 2020, with high-speed rail lines to London and Europe.

London Britannia Airport, would see London's Heathrow Airport closed and converted into a community of 300,000 new houses, according to a government-backed consortium behind the proposal for the A$81 billion (£47.3bn) project.

The runway configuration would allow three or four aircraft to operate at the same time, 24 hours a day, allegedly in all weather conditions.

Britannia Airport would be "car free, with no private car access". To streamline passenger movements, check-in and arrivals terminals would be located at London's King's Cross railway station and the Ebbsfleet International railway station on the HS1/Eurostar line, with high-speed rail links to the airport.

The airport would include a dock so that goods could be shipped to and from the new London Gateway superport rather than clogging up roads.

London Britannia Airport is the second of two proposals for an airport in the Thames estuary, but unlike a rival pitch from Foster+Partners would be constructed on an artificial island instead of converting the current outcropping Isle of Grain (as shown below).

Opting to build a bespoke island allows the location to be chosen to minimise noise and be tailored for transport links says the Thames Estuary Research and Development (Testrad) consortium formed by London Mayor Boris Johnson to study the options for estuary airports.

“In many respects, this is the most ambitious of all the airport proposals, the least contentious, the easiest and the most cost effective solution,” says Ian Mulcahey, managing director of international architectural firm Gensler, which is part of the consortium.

A new airport is needed to supplement or potentially replace the congested Heathrow Airport, which is currently running at an estimated 99% capacity.

London Britannia Airport would handle over 200 million passengers per year, making it one of the world's largest airports.

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