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Fracture Critical
The National Bridge Inventory (NBI) is a database, compiled by the Federal Highway Administration, with information on all bridges and tunnels in the United States that have roads passing above or below them. That is similar to the grade-crossing identifier number database, compiled by the Federal Railroad Administration, which identifies all railroad crossings. The bridge information includes the design of the bridge and the dimensions of the usable portion. The data is often used to analyze bridges and to judge their condition. The inventory is developed for the purpose of having a unified database for bridges to ensure the safety of the traveling public, as required by the Federal Aid Highway Act of 1968. It includes identification information, bridge types and specifications, operational conditions, bridge data including geometric data and functional description, and inspection data. Any bridge more than 20 ft (6 m) long used for vehicular traffic is included. Description Iden ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Federal Highway Administration
The Federal Highway Administration (FHWA) is a division of the United States Department of Transportation that specializes in highway transportation. The agency's major activities are grouped into two programs, the Federal-aid Highway Program and the Federal Lands Highway Program. Its role had previously been performed by the Office of Road Inquiry, Office of Public Roads and the Bureau of Public Roads. History Background The organization has several predecessor organizations and complicated history. The Office of Road Inquiry (ORI) was founded in 1893. In 1905, that organization's name was changed to the Office of Public Roads (OPR) which became a division of the United States Department of Agriculture. The name was changed again to the Bureau of Public Roads in 1915 and to the Public Roads Administration (PRA) in 1939. It was then shifted to the Federal Works Agency which was abolished in 1949 when its name reverted to Bureau of Public Roads under the Department of Commerce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bridges
A bridge is a structure built to Span (engineering), span a physical obstacle (such as a body of water, valley, road, or rail) without blocking the way underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually something that is otherwise difficult or impossible to cross. There are many different designs of bridges, each serving a particular purpose and applicable to different situations. Designs of bridges vary depending on factors such as the function of the bridge, the nature of the terrain where the bridge is constructed and anchored, and the material used to make it, and the funds available to build it. The earliest bridges were likely made with fallen trees and stepping stones. The Neolithic people built boardwalk bridges across marshland. The Arkadiko Bridge (dating from the 13th century BC, in the Peloponnese) is one of the oldest arch bridges still in existence and use. Etymology The ''Oxford English Dictionary'' traces ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tunnels
A tunnel is an underground passageway, dug through surrounding soil, earth or rock, and enclosed except for the entrance and exit, commonly at each end. A pipeline is not a tunnel, though some recent tunnels have used immersed tube construction techniques rather than traditional tunnel boring methods. A tunnel may be for foot or vehicular road traffic, for rail traffic, or for a canal. The central portions of a rapid transit network are usually in the tunnel. Some tunnels are used as sewers or aqueducts to supply water for consumption or for hydroelectric stations. Utility tunnels are used for routing steam, chilled water, electrical power or telecommunication cables, as well as connecting buildings for convenient passage of people and equipment. Secret tunnels are built for military purposes, or by civilians for smuggling of weapons, contraband, or people. Special tunnels, such as wildlife crossings, are built to allow wildlife to cross human-made barriers safely. Tu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
