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Immersed Tube Tunnel
An immersed tube (or immersed tunnel) is a kind of undersea tunnel composed of segments, constructed elsewhere and floated to the tunnel site to be sunk into place and then linked together. They are commonly used for road and rail crossings of rivers, estuaries and sea channels/harbours. Immersed tubes are often used in conjunction with other forms of tunnel at their end, such as a cut and cover or bored tunnel, which is usually necessary to continue the tunnel from near the water's edge to the entrance (portal) at the land surface. Construction The tunnel is made up of separate elements, each prefabricated in a manageable length, then having the ends sealed with bulkheads so they can be floated. At the same time, the corresponding parts of the path of the tunnel are prepared, with a trench on the bottom of the channel being dredged and graded to fine tolerances to support the elements. The next stage is to place the elements into place, each towed to the final location, in mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Undersea Tunnel
An underwater tunnel is a tunnel which is partly or wholly constructed under the sea or a river. They are often used where building a bridge or operating a ferry link is unviable, or to provide competition or relief for existing bridges or ferry links.Sullivan, WalterProgress In Technology Revives Interest In Great Tunnels New York Times, June 24, 1986. Retrieved 15 August 2010. While short tunnels are often road tunnels which may admit motorized traffic, unmotorized traffic or both, concerns with ventilation lead to the longest tunnels (such as the Channel Tunnel or the Seikan Tunnel) being railway electrification systems, electrified rail tunnels. Types of tunnel Various methods are used to construct underwater tunnels, including an immersed tube and a submerged floating tunnel. The immersed tube method involves steel tube segments that are positioned in a trench in the sea floor and joined together. The trench is then covered and the water pumped from the tunnel. Submerged flo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Oakland, California
Oakland is a city in the East Bay region of the San Francisco Bay Area in the U.S. state of California. It is the county seat and most populous city in Alameda County, California, Alameda County, with a population of 440,646 in 2020. A major West Coast of the United States, West Coast port, Oakland is the most populous city in the East Bay, the third most populous city in the Bay Area, and the eighth most populous city in California. It serves as the Bay Area's trade center: the Port of Oakland is the busiest port in Northern California, and the fifth- or sixth-busiest in the United States. A charter city, Oakland was municipal corporation, incorporated on May 4, 1852, in the wake of the state's increasing population due to the California gold rush. Oakland's territory covers what was once a mosaic of California coastal prairie, California coastal terrace prairie, oak woodland, and north coastal scrub. In the late 18th century, it became part of a large ''rancho'' grant in the c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
