When building a bridge over a large body of water, how do they get the pillars so deep into the water and how is the foundation secured?

Question

When building a bridge over a large body of water, how do they get the pillars so deep into the water and how is the foundation secured?

In: Engineering

Answer 1

[check it out](https://en.m.wikipedia.org/wiki/Cofferdam)

[this photo is a good visual](https://s3.ap-south-1.amazonaws.com/hansindia-bucket/5210_Classroomcofferpic.jpg)

Basically they make a little enclosed area and then suck out all the water from that area, essentially putting a dry hole in the middle of the water, then in that hole they build the bridge support.