Expert explains the stumbling blocks in building $20,000,000,000,000 tunnel that would get you from NYC to London in just 54 minutes

If you thought an underground tunnel transporting us between the US and the UK in less than an hour sounded too good to be true, you might be right.

Proposals have been put forward for a Transatlantic Tunnel linking New York and London, which could cost a staggering $20 trillion.

While the concept would be way more convenient than the current eight-hour flight, it sounds pretty terrifying to me.

It involves taking a 3,000 mph train across a 3,4000 mile long tunnel below the Atlantic ocean.

For context, the Shanghai Maglev - the world's fastest public train - travels at just 286 mph.

The Shanghai Maglev is the world's fastest train, traveling at 286 mph (Xiaoyang Liu/Construction Photography/Avalon/Getty Images)

It's reported that vacuum technology and the use of jet propulsion - where an engine thrust is produced by a fast-moving jet of fluid - could achieve unprecedented speeds, slashing the journey time down to just 54 minutes.

While Elon Musk reckons he knows the perfect company to build the Transatlantic Tunnel, it's actually a mammoth task which could take decades to complete.

One engineer took to social media to share why, exactly, the ambitious project might never happen.

Posting to expert community forum Stack Exchange, they pointed out that the Atlantic's depths pose some major issues from the off.

Delving as deep as 5,500 meters, scientists would need to examine the seabed's geological structure, identifying any faults, before they could even begin thinking about construction.

The train journey between New York and London could take less than an hour (Getty Stock Images)

This task would be incredibly time-consuming and could prove fruitless. For example, if materials in the seabed were too soft, then the tunnel wouldn't be physically supported and construction couldn't safely go ahead.

Even if the seabed's conditions were workable, though, depth would still be a major hurdle.

The engineer explained that assembling tunnel sections and ensuring they survive the water pressure at 5,500 meters would be difficult.

"Additionally, such deep water will increase the ground stresses in the rock in the seabed, which will be problematic for an excavated tunnel," they said.

Then there's the important aspect of ventilation, with the engineer foreseeing ventilation shafts being 'problematic' to construct and support.

The underwater tunnel would be up against a whole host of issues (Yongyuan Dai/Getty Images)

They could be hit by 'whales, ships and submarines,' while ventilation fans would need to be placed at the ends of the vent tunnels, which would be 'large and... consume a lot of electricity.'

The biggest hurdle of all, though, is a huge mid-ocean volcano system known as the Mid-Atlantic Ridge.

Wrapping around Earth like seams on a baseball, it stretches almost 40,390 miles, with the average water depth to the top of the ridge some 2,500 meters.

As the Stack Exchange engineer explains: "This is an active volcanic zone that is pushing apart the continental plates that separate the Americas from Europe and Africa. This ridge is visible above the water on Iceland."

They add: "Putting a tunnel on or through the Mid Atlantic Ridge may not be possible. If it were... the tunnel would require regular maintenance to remedy damage done by the Ridge."

Not to mention that erecting ventilation shafts through active volcanos... is probably not even worth attempting.

As convenient as a quick, cross-continent train sounds, we shouldn't get our hopes up anytime soon. Anyway, where's my passport?