An elevated railway or elevated train is a railway with the tracks above street level on a viaduct or other elevated structure. The railway may be broad-gauge, standard-gauge or narrow-gauge railway, light rail, monorail, or a suspension railway. Elevated railways are normally found in urban areas where there would otherwise be multiple level crossings. Usually, the tracks of elevated railways that run on steel viaducts can be seen from street level.
Liverpool Overhead Railway, May 1951
NS 93 train on an elevated portion of the line 5 of the Santiago Metro
Two Wuppertal Schwebebahn trains meet above the street
Chicago "L" elevated tracks
A monorail is a railway in which the track consists of a single rail or a beam. Colloquially, the term "monorail" is often used to describe any form of elevated rail or people mover. More accurately, the term refers to the style of track. Monorail systems are most frequently implemented in large cities, airports, and theme parks.
Chongqing Rail Transit has the longest and busiest monorail system in the world, with Line 3 being the longest and busiest single monorail line.
São Paulo Metro Line 15, is the longest and busiest monorail line in the Americas, and second worldwide.
Monorail on concrete columns in Chongqing, China
Gyroscopically balanced monorail (1909) by Brennan and Scherl