Floating Intercontinental Bridge
June 2, 2008 at 11:42 pm #556
I’m thinking in terms of combining the two concepts, the flat casting of Pelagic, http://pelagic.wavyhill.xsmail.com/ , with the submerged floatation of Seastead, http://www.seastead.org/ , to build a bridge along the equator to connect the continents out of sections connected like vertebrae. The basic structure of the sections is a pair of hollow hyperbolic arches (like McDonalds) with hollow tubes at the bottoms of the arches. The tubes are submerged to provide flotation and also function as transit corridors. The V area between the arches has paths for surface traffic in a landscaped park setting, like a long linear city street. The seaward facing sides of the arches are private balconies. Sealanes are accomodated with submerged platforms incorporating tubes to contine the underwater tunnels.
The hyperbolic structure transfers the predominant compressive loads of gravity along the structure, minimizing tensile loads.
I favor fiber reinforced concrete with glass or carbon steel fibers. Corrosion only penetrates 2-3 millimeters with the steel, not an issue with the glass. Leaving the surface untreated lets desalinized water weep through to be collected in a sump as fresh water. The concrete acts as a giant desal filter. Sea life can attach to the outer surface as an artificial reef.
At Seastead’s estimate of $50/sq ft habitable area, current illegal immigrants paying smugglers $5000 per person could buy a 10’x10′ space in the habitat instead-a very large potential market. Habitat sections can be designed to produce saleable products and power along with self sufficiency in food and energy. Additional income is derived from a share in the profits from through traffic across the bridge, along with pipelines carrying excess desal water and powerlines with excess energy to the continents.
A 25,000 mile equatorial band as a linear single street city would be geometrically equivalent to a 35 mile by 35 mile city laid out in a grid of streets at tenth mile spacings in each direction (2 directions x 35 miles x 10 streets per mile x 35 miles per street = 24,500 miles). This is smaller than Los Angeles, which is laid out in this kind of grid. The character of the surface street would be reminiscent of San Francisco or Paris, with a few levels mixed business and residential above the landscaped area and paths below.
The two outer tunnels carry high speed express traffic (300 miles an hour) in opposite directions. The two inside tubes carry local trafic in opposite directions. Habitat sections have a vertical shaft over these tubes to lift passenger vehicles and cargo containers to the habitation levels. The submerged platforms for tunneling under sealanes and allowing ship traffic are useful areas for switching between the express and local tubes. They are also logical attach points for anchoring with hollow tubes to the floor for seakeeping and cold water supply for nutrients and OTEC. Pairs of cement tubular piers going off at angles to either side of the bridge may be cheaper than cables. The sea lanes are logical places for lateral development of floating piers for shipping to transfer cargo to and from the bridge. Six equally spaced locations around the equatorial band also serves as terminals for future space elevator anchor points.
A minimum size for an arched section is about 150′ high with the double arch section being about 300′ wide based on the Seastead design. A section includes living areas with exterior balconies and interior areas for commercial use, hydroponics, storage, and manufacturing. Mariculture pens can extend from the sections. Wave power can be extracted by capturing wave crests through slots in the arches near sealevel and running the water through a turbine before it exit through a drain below sealevel.
The links I have for fiber concrete are http://www.fibermesh.com/shotcrete/faqs.asp and http://www.stormingmedia.us/38/3859/A385963.html . The desal is based on theory. The fibers in carbon steel fiber reinforced concrete only corrode 2-3 millimeters, meaning the salt does not penetrate further. Glass fiber is completely corrosion resistant. Water vapor passes through concrete and condenses on the inside. The question is if there is enough volume to be useful for desal. On a large structure there could be. In any event it is better to build from inherently corrosion free materials than to rely on surface coatings which are a maintenance item and potential failure point.
The main bridge colony would have a governing organization, preferably as a company jointly owned by the owners of the individual sections. As a profit making entity, it would pay dividends to the shareholders from profits from carrying through traffic, power sales to land based utilities, fresh water and leasing of rights of way for power and communications. Use of transit facilities by residents would be charged against the dividends or additional cost to heavy users.
A non-voting class of stock can be issued to non-residents for initial investment. Promotion of the project as a transportation and utility company is a strenth in that the project has inherently marketable products and services rather than relying on a volatile politically based economy as a tax haven. The use of import/export loans from industrial nations is a viable option for financing. They benefit from a new market for exports, transportation opening up new markets, and an alternative haven for their current perceived immigration problems.
I would downplay the libertarian aspects of the project, but build it into the structure of the organization in the form of contractual agreements by those connecting platforms to the structure. It is in a sense a governing organization which pays its members rather than taxing them. The opening of a vast new frontier by providing efficient easy access has historically led to maximum personal freedom, as in the American west opened up with the building of railroads. The geometry of above water segments separated by the sealanes will lead to a variety of local communities having different characters, some freer than others. Those wanting complete independence can set up free platforms close to the bridge.
The possibility of terrorism is best handled by the bridge taking a strictly neutral position in international matters. Last I heard, the Swiss were not overly concerned with terrorist threats.June 3, 2008 at 8:57 am #2893
I was thinking lately that if you’d tie enough seasteads together loosely enough, you could end up with some form of “low density land” on the sea, and that would be really neat to use that to connect together islands. Imagine connecting the polynesian islands together through a dynamic floating bridge of seasteads like that: costs of travel and trade would plummet internally.June 4, 2008 at 7:49 am #2916
There are a number of places with fairly close spans under a hundred miles which could be connected with inhabited floating bridges, like the Strait of Gibralter. These would be good places to start. Connecting archipelagos would also be cool. The original London Bridge is an historical example of an inhabited bridge complete with business district.
My ultimate aim is to bridge the equator, to connect a series of space elevators which also serve as tethers for a cable stayed ring colony around the earth, stationed out past geosynchronous orbit to create artificial gravity from its spin from the earth’s rotation.June 4, 2008 at 9:46 am #2919
You’d have to have some pretty big arches, placed very regularly, or you would interrupt shipping, which tends to piss people off.June 4, 2008 at 5:19 pm #2956
Yes, there would be totally submerged TLP box sections connecting the habitat segments at regular intervals to allow surface traffic to cross. These are used as switching areas between tracks for the rail system, anchorage points, and OTEC.October 10, 2009 at 4:35 pm #8115
This thread reminded me a recent mecha anime ‘Gundam 00’ the space elevator and the ring, though instead of using the ring for residental purposes they use it solely for solar energy generation.
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