Tunnel

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. Tunnels can be connected together in tunnel networks. A tunnel is relatively long and narrow; the length is often much greater than twice the diameter, although similar shorter excavations can be constructed, such as cross passages between tunnels. The definition of what constitutes a tunnel can vary widely from source to source. For example, in the United Kingdom a road tunnel is defined as "a subsurface highway structure enclosed for a length of or more." In the United States, the NFPA definition of a tunnel is "An underground structure with a design length greater than and a diameter greater than ." In the UK, a pedestrian, cycle or animal tunnel beneath a road or railway is called a subway, while in New York City that word usually refers to the city's underground rapid transit system (sometimes casually referred to as "the train"). Underground railway and rapid transit systems in other places have other names as well, such as the "Underground" or the "Tube" in London, the "Subway" in Glasgow, and the "Metro" in Newcastle as well as in Paris and Montreal.

Quantification of influence of monitoring duration on measured traffic action effects on fatigue of RC deck slabs of road bridges

Quantification of influence of monitoring duration on measured traffic action effects on fatigue of RC deck slabs of road bridges