The $20-trillion tunnel that could link New York and London

Proposals for a tunnel connecting the U.K. to the U.S. underneath the Atlantic Ocean have resurfaced, but with a price tag of almost $20 trillion, the project is a big ask.

The idea of a “Transatlantic Tunnel” has existed for a while, though issues of scale, cost, and utility have long stifled any realistic developments. While a flight between London and New York City takes around eight hours, it had previously been unclear if trains running underneath the ocean would make the journey fast enough to justify the cost of construction.

With the two global cities being over 3,000 miles apart, construction would take several years—the 23.5-mile Channel Tunnel linking England and France took six years to construct—and require significant investment. Estimates over the cost have reached as high as £15.5 trillion, the equivalent of $19.8 trillion.

However, developments in vacuum tube technology have made the concept more viable. By creating a vacuum within the tunnel and using pressurized vehicles, trains traveling along the structure could theoretically reach speeds of more than 3,000 mph, making the journey between London and New York barely an hour long.

This is because trains would not face any air resistance within the tunnel, allowing them to reach higher speeds than unconventional trains. This design, which has seen new development in Indian transportation, is sometimes called a “hyperloop”.

Cutting the intercontinental journey down to a matter of minutes means that for the first time, the Transatlantic Tunnel justifies the hefty price tag that undersea construction comes with, as it would become significantly more efficient and environmentally friendly than flying.

However, there is still no set design for the tunnel. Various proposals have suggested a tunnel underneath the ocean floor, while others have suggested building it on stilts. One design even proposed making the tunnel float, held in place by cables attached to the ocean floor.

The Channel Tunnel linking France to the U.K. was built over a six-year period. If the trans-Atlantic tunnel were built at the same speed, it would take 782 years to cross the 3,000 gap between the U.S. and Britain.

Trains traveling through a vacuum were popularized by Elon Musk, who wrote a paper in 2013 that proposed sending capsules through a vacuum environment to reduce air resistance. Trials of the technology are underway in India and China, with plans to integrate it into their high-speed rail systems nationwide.

Newsweek has contacted hyperloop developers IIT-Madras for more information on the technology’s capabilities via email.

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