Archimedes bridge

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Two types of Submerged Floating tunnels

Water spanning structures: 1: Suspension bridge 2: Archimedes bridge 3: Immersed tube 4: Undersea tunnel

Diagram of the buoyancy effect

An Archimedes bridge (also suspended tunnel or submerged floating tunnel—SFT^[1]) is a submerged tunnel that floats in water. It is a sustainable bridge that employs hydrostatic thrust—or Archimedes Principle—first described by Archimedes.^[2]

The tube is placed underwater, deep enough to avoid water traffic and weather, but not so deep that high water pressure needs to be dealt with—usually 20–50 m (60–150 ft) is sufficient. Cables either anchored to the Earth^[2] or pontoons at the surface^[3] prevent it from floating to the surface or submerging, respectively.

1 Applications
2 Norwegian projects
3 Chinese projects
4 See also
5 Notes
6 External links

[edit] Applications

The submerged floating tunnel allows construction of a tunnel with a shallow alignment in extremely deep water, where alternatives are technically difficult or prohibitively expensive. Likely applications include fjords, deep, narrow sea channels, and deep lakes.^[4]

The archimedes bridge has been proposed the as the most viable alternative to build the Transatlantic tunnel by the Extreme Engineering series from Discovery Channel^[5].

[edit] Norwegian projects

The Norwegian Public Roads Administration has, in cooperation with contractors and consultants, developed four alternatives of the submerged floating tunnel, three in concrete and one in steel. These four alternatives were officially approved to fulfill the requirements for crossing the Høgsfjord. The project was stopped due to changes in regional plans. ^[6]

[edit] Chinese projects

A consortium of European and Chinese engineers and scientists believe an Archimedes bridge would be feasible economically and technically in many places where conventional bridges or tunnels are not. The advantages include:

structural performance is independent of length
natural resistance to seismic and weather events

A project has commenced to build a 100m demonstration tunnel in Qiandao Lake in China eastern province of Zhejiang. When completed, the 100-meter-long bridge will be submerged in the water. It will look like an oval tube from outside. Inside it, two layers of one-way motorways will run though in the middle, with two railway tracks flanking them.^[7] The Qiandao Lake prototype will serve to help plan for the project of a 3,300-meter submerged floating tunnel in the Jintang Strait, in the Zhoushan prefecture-level city, also situated in Zhejiang.^[8]^[9]^[1]

Indonesia has also expressed interest in this technology.^[9]^[10] As an archipelagic country, consisting of more than 13 thousand islands, Indonesia could benefit of such tunnels. The conventional transportation service between islands is made mainly by ferries. Archimedes bridges could thus be an alternative to connect adjacent islands, in addition to bridges.