Tunnel Shield Under River
You've got it! The first underwater tunnel was built with a tunnel shield. You could build a mile-long tunnel here in a couple of months with this reliable method.

Learn more				Tunnel Score: 100

The tunnel shield supports the soggy soil so it won't cave in on you as you dig.

Here's how it works:
The shield, which looks like a huge tin can, cuts through the earth and squeezes the wet ground in at its face. Tunnel workers gather the muck as it pours in. They toss the wet earth on conveyor belts, which carry the excess mud out of the tunnel. The "tin can" supports the wet, muddy ground while the tunnel workers construct a tunnel lining, ring by ring, inside the "can." This lining eventually forms a long, strong, waterproof tunnel -- perfect for your underwater highway tunnel!

Today, tunnel engineers are using an even faster method, called the immersed tube technique, to construct tunnels under water.

Start over		Check out another tool or technique		Try this tool in the next location