Monorail
A monorail is a form of urban rail transit in which trains run on or are suspended from a single rail or beam. Monorails typically provide intermediate transport capacity, generally greater than trams and less than heavy metro systems. The term is often applied colloquially to any elevated rail or people mover, though it refers more precisely to the single-beam track structure.
Two principal types exist: straddle-beam monorails, in which vehicles ride atop a concrete or steel beam, and suspended monorails, in which vehicles hang beneath the guideway. The straddle-beam design, descended from the ALWEG system of the 1950s, dominates modern installations; suspended systems remain in service on the Wuppertal Schwebebahn (1901, the oldest monorail in operation) and the Chiba Urban Monorail (the largest suspended network). Monorail systems are most frequently implemented in large cities, airports, and theme parks.
Early monorail experiments date to the 1820s, with the first load-bearing systems appearing in the late 19th century. Modern mass-transit monorails emerged in the second half of the 20th century, principally in Japan, where Tokyo Monorail has carried over 1.5 billion passengers since 1964. Chongqing Rail Transit in China operates the world's largest and busiest monorail system, with Line 3 alone carrying over 680,000 passengers per day. Monorails are also used in airport shuttle services, niche applications including agriculture and mining, and amusement parks. Monorail systems have been depicted extensively in popular culture, from the "Fahrenheit 451" film (1966) to The Simpsons episode "Marge vs. the Monorail" (1993), which the Monorail Society has credited with shaping negative public perceptions of the technology.