Here's the latest hyperloop hype from CES, now proposed as a means of
providing very fast links between Heathrow, Gatwick and Stansted, instead
of a new runway:

http://www.telegraph.co.uk/technology/2018/01/14/build-heathrow-gatwick-hyperloop-instead-third-runway-says-branson/

Extracts:

His aspirations to send tourists into space have been notorious for
setbacks, missed deadlines and broken promises. However, Sir Richard
Branson’s latest venture believes it has the answer to Britain’s runway
expansion dilemma, proposing a system of high-speed “hyperloops� to ferry
passengers between London’s airports.

Virgin Hyperloop One, a California start-up chaired by the billionaire, has
been studying the possibility of a series of high-speed tubes between
Heathrow, Gatwick and Stansted which it says would allow passengers to
travel between the airports in as little as five minutes.

It says the hyperloop, a proposed transport system that involves futuristic
pods travelling through low pressure tubes at speeds of up to 670 mph,
would effectively turn London’s three major airports into one “hub�. Virgin
Hyperloop One’s chief executive Rob Lloyd said the plan could remove the
need for a third runway at Heathrow.

“[We’re] thinking about how technology could make it a much different
proposition than the third runway. “You’d think of this as moving between
terminals instead of moving between airports,� he said.

Lloyd said the company’s technical advisory board, made up of researchers
and infrastructure experts, had assessed the possibility of hyperloops
connecting the airports. They estimated it would take five minutes between
Heathrow and Gatwick, and seven to Stansted.

…

However, the idea has been mocked as the epitome of Silicon Valley blue-sky
thinking, with cost estimates already soaring above Musk’s predictions and
engineers warning of the potential safety risks. The only successful tests
of the technology to date have been unmanned trials on Virgin Hyperloop
One’s 500-metre track in the Nevada desert, which have reached a maximum
speed of 240 mph.

It has drawn inevitable comparisons to Virgin Galactic, Sir Richard’s space
tourism venture, which originally planned to start flights in 2011 but has
been repeatedly hit by delays.

Virgin Hyperloop One wants to have a fully-working hyperloop transporting
cargo by 2021, with passengers set to follow soon after, although the
company has not yet signed a deal to build a track and would have several
regulatory barriers to overcome.

In December, a paper published by the Department for Transport said a
hyperloop in the UK would be “at least two decades away�. The DfT’s science
advisory council said potential problems with emergency braking, power
failures and cyber attacks, as well as the need for largely straight
routes, presented a number of “technical challenges�.

… continues