The Oceanic Bridge

1. Average depth of the Atlantic Ocean:

According to Wikipedia:
http://en.wikipedia.org/wiki/Atlantic_Ocean
"The average depth of the Atlantic, with its adjacent seas, is 3,339 metres (10,950 ft); without them it is 3,926 metres (12,880 ft). The greatest depth, 8,605 metres (28,230 ft), is in the Puerto Rico Trench. The Atlantic's width varies from 2,848 kilometres (1,770 mi) between Brazil and Sierra Leone to over 6,400 km (4,000 mi) in the south."

For comparison, the depth of the ocean's deepest point at the Mariana Trench is approximately 33,000 feet:
http://photos1.blogger.com/photoInclude/x/blogger/7753/1056/1600/287845/ocean%20zones.gif


2. The curvature of the earth:
-How would the curvature of the earth impact the bridge's design?
Consider this sketch by How Stuff Works-
http://www.howstuffworks.com/question65.htm



3. The structure itself:
The "Half-Pipe" Idea
-Instead of drilling columns into the ocean floor could a beam be constructed that could support the weight of the bridge's columns?
-How much weight would the beam have to support?
-What materials are best?
-Would it be underwater and if so, what about water pressure, corrosion, etc.?
-Could the beam float or be filled with water?
-How thick would it be and what structures would support the beam at its weakest point, presumably the middle?



The Oil Rig Platform Model
According to Solar Navigator:
http://www.solarnavigator.net/oil_rigs.htm
"Semi-submersible Platforms having legs of sufficient buoyancy to cause the structure to float, but of weight sufficient to keep the structure upright. Semi-submersible rigs can be moved from place to place; and can be lowered into or raised by altering the amount of flooding in buoyancy tanks; they are generally anchored by cable anchors during drilling operations, though they can also be kept in place by the use of steerable thrusters. Semi-submersible can be used in depths from 600 to 6,000 feet (180 to 1,800 m)."
The Oil Rig Hibernia, below, as a structure demonstrates that structures can be built to withstand the ocean climate and that the technology exists to to go to depths up to 6,000 feet. Perhaps a series of these structures, similarly built, could be placed at certain distances apart to create a bridge that was more flexible and at the same time sturdy enough to support human traffic across long distances.