An elevated railway or elevated train (also known as an el train for short) is a rapid transit railway with the tracks above street level on a viaduct or other elevated structure (usually constructed from steel, cast iron, concrete, or bricks). 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.