How do they put a tunnel underwater?

Question

My father told me my Grandfather helped build the tunnel to Canada..It got me wondering . How do they get or build a tunnel underwater without getting it full of water.
My Grandfather was dead when I found out he built it. So I couldn't ask him.

Answer 1

There are about four ways.

In one they dig a hole near the shore and then have the tunnel diggers start digging through the ground under the water toward the other side. They keep the tunnel and those ends of the tunnel under high pressure air to keep the water out. That is why tunnels are dangerous to build. That is the oldest way.

In another way (for muddy areas) they have prefabricated sections that they drop into the water to the bottom and then bolt together followed by air pressurizing to blow the water out of the finished sections. They do that section by section till they are done.

In another they take prebuilt sections and jack them through the ground at the bottom of the section so that they move forward one length and then add another on the pushing side and push the first section even further ahead.

Other way (like for rocky areas) is to have a large rotary driller that cuts through a hole the size of the tunnel and keeps pressing forward and cutting.

Answer 2

Wow! I am so glad you asked this question. I don't have an answer for you, but I was wondering the same thing. It seems to make sense to me that it would be built on land in sections and then installed under water. I always think of the Lincoln tunnel in New York City and what an "undertaking" that must have been for the engineers and builders. So amazing what can be done when minds are able to focus together to achieve a goal.

Best wishes!

Answer 3

The tunnel was built in the ground below the water.

Answer 4

They use a huge circular drill and shore up and cement the tunnel as they go along.