Subways

Subways were a major part of big cities that sprung up. "Subway" refers to parts mainly below ground, though parts may be on ground level or above ground. It is most useful in crowded areas.

=Construction Types:= Cut and Cover- Digging up streets, building tunnel, covering it Cover and Cut- Concrete slab laid and tunnel dug under Tunneler- Tunnel dug and lined at same time using precast concrete pieces

Longest in the world- London's subway system called //tube// or //underground//. Some lines so far below, elevators used. London first to have subway. 1863-Steam locomotives used 1890- Electrical used

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