"Tom Barry" wrote:
Mind you, a 200+km/h underground flying junction is not going to be the
most loony part of the proposal.

The real killer for Boris is a much, much simpler one; it doesn't have to be
a castle in the air; even an airport built on sand will fail.

The cost of underpinning both (all three?) runways to the seabed, at one
pile every twenty metres or so, will make costs astronomical, and put
building times well into the cathedral class.

Even a Low Tide Only Airport will need to be raised some 15 - 20 metres
*above* the level of the migrating sand, and firmly anchored 15 - 20 metres
*below* it .

It Ain't Gonna Happen.

--

Andrew