Today in Design we take a look at the Channel Tunnel that connects the United Kingdom to France. Spanning 31.4 miles the Channel Tunnel is the largest underwater tunnel with 23.5 submerged miles. Diving to a depth of 790 feet, the impressive infrastructure allows large freight and passenger trains to travel 99 miles per hour across the English Channel. The tunnel is home to the world’s largest vehicle shuttle, the Eurotunnel, as the tunnel does not allow vehicle traffic. With each tunnel clocking in at 25 feet in diameter, large freight trains are able to travel between the two countries with relative ease, but due to cheap airfare, the freight traffic was overestimated during initial projections. Engineers began digging the tunnel back in 1988 and finished the project in 1994. Tunneling was conducted from both the French and English side in hopes of reducing total construction time. In order to ensure the tunnel could be properly maintained, a third service tunnel was built for special vehicle and air ventilation systems. In addition, the specialized ports are used to help stabilize the change in tunnel pressure that occurs when trains are in operation. On top of being one of the seven wonders of the modern world, the Channel Tunnel successfully linked the UK to mainland Europe for the first time. We can think of at least three places in New York City alone where this sort of tunnel would be greatly appreciated.