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.
Etymology
The term possibly originated in 1897 from German engineer Eugen Langen, who called an elevated railway system with wagons suspended the "Eugen Langen One-railed Suspension Tramway" (Einschieniges Hängebahnsystem Eugen Langen).
Differentiation from other transport systems
Monorails have found applications in airport transfers and medium-capacity metros. To differentiate monorails from other transport modes, the Monorail Society defines a monorail as a "single rail serving as a track for passenger or freight vehicles. In most cases, rail is elevated, but monorails can also run at grade, below grade, or in subway tunnels. Vehicles either are suspended from or straddle a narrow guide way. Monorail vehicles are wider than the guideway that supports them."
Similarities Monorails are often elevated, sometimes leading to confusion with other elevated systems such as the Docklands Light Railway, Vancouver SkyTrain, the AirTrain JFK and cable-propelled systems like the Cable Liner people mover, which run on two rails.
Monorail vehicles often appear similar to light rail vehicles and can be staffed or unstaffed. They can be individual rigid vehicles, articulated single units, or multiple units coupled into trains. Like other advanced rapid transit systems, monorails can be driven by linear induction motors; like conventional railways, vehicle bodies can be connected to the beam via bogies, allowing curves to be negotiated.
Monorails are sometimes used in urban areas alongside conventional parallel-railed metro systems. Mumbai Monorail serves alongside Mumbai Metro, while monorail lines are integrated with conventional rail rapid transit lines in Bangkok's MRT network.
Differences Unlike some trams and light rail systems, modern monorails are always separated from other traffic and pedestrians due to the geometry of the rail. They are both guided and supported via interaction with the same single beam, in contrast to other guided systems like rubber-tyred metros, such as the Sapporo Municipal Subway, or guided buses or trams, such as Translohr. Monorails can also use pantographs.
As with other grade-separated transit systems, monorails avoid red lights, intersection turns, and traffic jams.Ryan, Phillip "Monorails (All Aboard!)" (2010) Surface-level trains, buses, cars, and pedestrians can collide with one another, while vehicles on dedicated, grade-separated rights-of-way such as monorails can collide only with other vehicles on the same system, with far fewer opportunities for collision. As with other elevated transit systems, monorail passengers receive sunlight and views.Schafer, Mike "American Passenger Train" (2001) Monorails can be quieter than diesel buses and trains. They obtain electricity from the track structure, whereas other modes of transit may use either third rail or overhead power lines and poles. Compared to the elevated train systems of New York, Chicago, and elsewhere, a monorail beamway casts a narrower shadow.Dorin, Patrick C. "American Passenger Trains: WWII to Amtrak" (2009)
Conversely, monorails can be more expensive than light-rail systems that do not include tunnels. In addition, monorails must either remain above ground or use larger tunnels than conventional rail systems, and they require complex track-switching equipment.
Maglev Under the Monorail Society's beam-width criterion, some, but not all, maglev systems are considered monorails, such as the Transrapid and Linimo. Maglevs differ from other monorails in that they do not physically contact the beam while moving.
History
Early years The first monorail prototype was made in Russia in 1820 by Ivan Elmanov. Attempts at creating monorail alternatives to conventional railroads have been made since the early part of the 19th century.
The Centennial Monorail was featured at the Centennial Exposition in Philadelphia in 1876. Based on its design the Bradford and Foster Brook Railway was built in 1877 and ran for one year from January 1878 until January 1879.
Around 1879 a "one-rail" system was proposed independently by Haddon and by Stringfellow, which used an inverted "V" rail (and thus shaped like "Λ" in cross-section). It was intended for military use, but was also seen to have civilian use as a "cheap railway". Similarly, one of the first systems put into practical use was that of French engineer Charles Lartigue, who built a line between Ballybunion and Listowel in Ireland, opened in 1888 and lasting 36 years, being closed in 1924 (due to damage from Ireland's Civil War). It used a load-bearing single rail and two lower, external rails for balance, the three carried on triangular supports. It was cheap to construct but tricky to operate. Possibly the first monorail locomotive was a 0-3-0 steam locomotive on this line. A high-speed monorail using the Lartigue system was proposed in 1901 between Liverpool and Manchester.
The Boynton Bicycle Railroad was a steam-powered monorail in Brooklyn on Long Island, New York. It ran on a single load-bearing rail at ground level, but with a wooden overhead stabilizing rail engaged by a pair of horizontally opposed wheels. The railroad operated for only two years beginning in 1890.
The Hotchkiss Bicycle Railroad was a monorail on which a matching pedal bicycle could be ridden. The first example was built between Smithville and Mount Holly, New Jersey, in 1892. It closed in 1897. Other examples were built in Norfolk from 1895 to 1909, Great Yarmouth, and Blackpool, UK, from 1896.
1900s–1950s Early designs used a double-flanged single metal rail alternative to the double rail of conventional railways, both guiding and supporting the monorail car. A surviving suspended version is the oldest system still in service: the Wuppertal monorail in Germany. Also in the early 1900s, gyro monorails with cars gyroscopically balanced on top of a single rail were tested, but never developed beyond the prototype stage. The Ewing System, used in the Patiala State Monorail Trainways in Punjab, India, relies on a hybrid model with a load-bearing single rail and an external wheel for balance. A high-speed monorail using the Lartigue system was proposed in 1901 between Liverpool and Manchester.
In 1910, the Brennan gyroscopic monorail was considered for use to a coal mine in Alaska. In June 1920, the French Patent Office published FR 503782, by Henri Coanda, on a "Transporteur Aérien" (Air Carrier). One of the first monorails planned in the United States was in New York City in the early 1930s, scrubbed for an elevated train system."America's First Monorail Line Planned For New York." "Popular Mechanics", November 1930, p. 71.
The first half of the 20th century saw many further proposed designs that either never left the drawing board or remained short-lived prototypes. Another project created on the layout was the ball-bearing train by Nikolai Grigorievich Yarmolchuk. This train moved on spherical wheels with electric motors embedded in them, which were located in semi-circular chutes under a wooden platform (in the full-scale project the trestle would have been concrete). A model train, built to 1/5 scale to test the vehicle concept, was capable of reaching speeds of up to 70 km/h. The full-scale project was expected to reach speeds of up to 300 km/h.
1950s–1980s
In the latter half of the 20th century, monorails had settled on using larger beam- or girder-based track, with vehicles supported by one set of wheels and guided by another. In the 1950s, a 40% scale prototype of a system designed for speed of on straight stretches and on curves was built in Germany."German's Develop Fast Monorail System For High Speed Travel" "Popular Mechanics", January 1953, p. 127. There were designs with vehicles supported, suspended, or cantilevered from the beams. In the 1950s the ALWEG straddle design emerged, followed by an updated suspended type, the SAFEGE system. Versions of ALWEG's technology are used by the two largest monorail manufacturers, Hitachi Monorail and Bombardier.
In 1956, the first monorail to operate in the US began test operations in Houston, Texas."First U.S. Monorail Has Trial Run." "Popular Mechanics", June 1956, p. 77. Disneyland in Anaheim, California, opened the United States' first daily operating monorail system in 1959. Later during this period, additional monorails were installed at Walt Disney World in Florida, Seattle, and in Japan. Monorails were promoted as futuristic technology with exhibition installations and amusement park purchases, as seen by the legacy systems in use today. However, monorails gained little foothold compared to conventional transport systems. In March 1972, Alejandro Goicoechea-Omar had patent DE1755198 published, on a "Vertebrate Train", built as an experimental track in Las Palmas de Gran Canaria, Spain. Niche private enterprise uses for monorails emerged, with the emergence of air travel and shopping malls, with shuttle-type systems being built.
1980s–present
From the 1980s, most monorail mass transit systems have been in Japan, with a few exceptions. Tokyo Monorail is one of the world's busiest, averaging 127,000 passengers per day and having served over 1.5 billion passengers since 1964. China began development of monorails in the late 2000s and is already home to the world's largest and busiest monorail system, with mass transit monorails under construction in several cities. A Bombardier Innovia Monorail-based system is under construction in Wuhu, and several "Cloudrail" systems developed by BYD are under construction in cities such as Guang'an, Liuzhou, Bengbu, and Guilin. Monorails have seen continuing use in niche shuttle markets and amusement parks.
Modern mass transit monorail systems use developments of the ALWEG beam and tire approach, with only two suspended types in large use. Monorail configurations have also been adopted by maglev trains. Since the 2000s, with the rise of traffic congestion and urbanization, there has been a resurgence of interest in the technology for public transport, with a number of cities such as Malta and Istanbul investigating monorails as a possible mass transit solution.