Elevated railroad

An elevated railway (also known as an El rail or simply an El for short, and, in Europe, as an overhead railway) is a rapid transit railway with the tracks above street level on a viaduct or other elevated structure (usually constructed of steel, concrete, or brick). The railway may be standard gauge, narrow gauge, light rail, monorail, or a suspension railway. Elevated railways are usually used in urban areas where there would otherwise be a large number of level crossings. Most of the time, the tracks of elevated railways that run on steel viaducts can be seen from street level.

The earliest elevated railway was the London and Greenwich Railway on a brick viaduct of 878 arches, built between 1836 and 1838. The first 2.5 miles (4.0 km) of the London and Blackwall Railway (1840) was also on a viaduct. During the 1840s there were other schemes for elevated railways in London that did not come to fruition.

From the late 1860s onward elevated railways became popular in US cities. The New York West Side and Yonkers Patent Railway operated with cable cars from 1868 to 1870, thereafter locomotive-hauled. This was followed by the Manhattan Railway in 1875, the South Side Elevated Railroad, Chicago (1892–), and the elevated lines of the Boston Elevated Railway (1901–). The Chicago transit system itself is known as "L", short for "elevated". The Berlin Stadtbahn (1882) and the Vienna Stadtbahn (1898) are also mainly elevated.

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