For centuries, mountains and lakes posed massive problems for engineers.
In both cases, they make travel nearly impossible and can make trips longer by days or months to bypass obstacles.
However, with the invention of Marc Isambard Brunel and Thomas Cochrane’s invention of the tunneling shield in the 19th century, that all began to change. Tunnels could go deeper — underwater through bedrock — allowing for quicker travel times.
From particle accelerators to portals through Switzerland’s famous Alps, today’s tunnels built with advanced Tunnel Boring Machines make Brunel’s original London Thames tunnel seem tiny by comparison. For the purposes of our roundup, we excluded most metro tunnels, which are often built by cut-and-cover methods instead of boring, and water tunnels, which humans can’t travel through (easily, at least.)
These are the world’s 12 longest tunnels:
12. LEP Tunnel
Location: CERN, Switzerland/France, Europe
Length: 16.6 miles.
Perhaps the most interesting tunnel on this list, the Large Electron-Positron collider tunnel is the only one on the list you’d have some trouble trying to travel through. Built in 1988, the tunnel at CERN’s complex on the Franco-Swiss border has been the home to several particle accelerators used by nuclear researchers at the center.
11. London Underground Northern Line
Oli Scarff/Getty Images
Location: London, England (from Morden to East Finchley)
Length: 17.3 miles
This portion of the Tube’s Northern Line is still the United Kingdom’s longest railway tunnel. Despite the exclusions of many other metro tunnels on this list, this portion makes the cut because the entire length was bored through solid rock beneath London’s streets.
10. Taihang Tunnel
Location: Tailhang, China
Length: 17.3 miles
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