Could a suspension bridge be built with floating caissons in place of the central towers?

Question

Like say, if the water in the mid-span was too deep to make building support towers from the floor of the body of water economically feasible.

It has to be tall enough to allow major cargo and cruise ships through. I'm thinking about Elliott Bay, in Seattle. There is no bridge like that in "Seattle Bay" (although, it's called Elliott Bay in Seattle. . .) Anyway, yeah, I was thinking of two major towers on dry land to give it its major support and stability. The span would have to be two miles from shore to shore. It is meant as a replacement for the Alaskan Way Viaduct, a public danger from earthquake, and a major eyesore that eats up Seattle's waterfront. Over 100,000 people need to pass over it a day.

Check out this link for design info:

http://library.thinkquest.org/J002223/types/suspension.html

Answer 1

I think there is a floating bridge like that in Seattle harbor where the water is about 600 feet deep.

Answer 2

I would say, without knowing the details about the body of water involved, that the answer is 'no'. However, why does it have to be a suspension bridge? A conventional floating bridge might be feasible, with suspension 'connectors' where it reached land.

Answer 3

If the towers were built with floating caissons, the towers would sway too much, fore and aft, side to side, up and down.

It'd make "galloping gerty" in the Tacoma Narrows look like a ride on a dime-store pony.

Answer 4

No. The whole idea behind suspension
bridges is that you can build bridges
5 miles long, rather than 100 feet long.