Tunnel

A tunnel is an underground passage. When designed for use by traffic, it may be called an underpass.

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A tunnel may be for pedestrians and/or cyclists, for general road traffic, for motor vehicles only, for rail traffic, or for a canal. Some are constructed purely for carrying water (for consumption, for hydroelectric purposes or as sewers), while others carry other services such as telecommunications cables. There are even tunnels designed as wildlife crossings for European badgers and other endangered species.

Related Topics:
Pedestrian - Cyclist - Motor vehicle - Rail - Canal - Hydroelectric - Sewers - Telecommunications - Wildlife crossing - European badger - Endangered species

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In the UK a pedestrian tunnel or other underpass beneath a road is called a "subway". This term was also used in the past in the US, but is now used to refer to underground mass transit systems, generally called metros outside the US.

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The central part of a metro or subway network is usually built in tunnels. To allow non-level crossings, some lines are in deeper tunnels than others. At metro stations there are usually also pedestrian tunnels from one platform to another. Often, ground-level railway stations also have one or more pedestrian tunnels under the railway to enable passengers to reach the platforms without having to walk across the tracks.

Related Topics:
Subway - Platform - Railway station

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