The infrastructure projects of the future have the potential to one day break down geographical barriers and make distant lands a simple commute, some believe. One idea that put forward by futurists more than a century ago is the speculative concept of a tunnel between Britain and the United States.

The two nations have long been known for their “special relationship” – despite recent criticism from the Trump administration – and continue to have close ties despite being separated by some 3,400 miles of ocean. Flying from London to New York currently takes around eight hours, but some have suggested that in the future, modern technology could help turn transatlantic tunnel into a journey of less than an hour.

Some people have imagined the far out idea of constructing a tunnel thousands of miles long under the Atlantic, which is miles deep in some areas.

That alone would present extraordinary technology and timescale challenges.

For context, the Channel Tunnel runs just 23.5 miles under the sea between England and France, took six years to build.

Over the years various approaches have been suggested for how it could be done, such as building it entirely under the seabed, constructing a tube suspended above the seabed or even a combination of the two.

Some have suggested that an alternative to the profound logistical hurdles of building a tunnel that long could to have a floating tunnel some 49 metres below the ocean surface made from tens of thousands of pre-fabricated sections and cables.

It’s speculated that this approach would allow trains to pass between the two continents, whilst avoiding the crushing pressure of the lower depths and steering clear of ships and treacherous weather on the surface.

Most theoretical discussions of such a tunnel envision it being built for trains rather than vehicles, as car journeys would take several days and additional infrastructure would be required to support drivers making the trip.

The notion of such a tunnel has popped in and out of discussion over the years, but reentered the public imagination following advancements in the study of vactrain technology, which involves vacuum tubes and magnetic levitation.

Scientists have speculated vactrains would theoretically be able to travel at speeds of up to 5,000mph, a speed that – if ever achieved – would reduce the London to New York City journey time to just 54-minutes.

Billionaire tech entrepreneur and world’s richest man Elon Musk has previously expressed belief it could work and be financially feasible.

Last December, as he responded to a post on X suggesting that such an idea would cost $20trillion (around £14.8trn), the tech titan said his firm, The Boring Company “could do it for 1000X less money”.

The speculative figure is often cited as the estimated cost, a rough factoring in of the vast and prohibitative level of investment such a project would likely require.

Because of that, and the gaps in technology required for such an undertaking, no serious proposals are currently being considered by governments on either side of the pond.

But in a world of reusable rockets and rapidly advancing artificial intelligence, the prospect of a trip down to Manhattan for an afternoon perhaps doesn’t seem so far-fetched.