A monorail is a transportation system based on a single beam. The term is also used variously to describe the beam of the system, or the vehicles travelling on such a beam or track. The term originates from the contraction of the words mono (single) and rail, from as early as 1897, as early systems used metal rails. The transportation system is often referred to as a railway.

Differentiation from other transport systems

Monorail systems have found shared applications in the transportation market in airport transfer and some medium capacity metro systems. To differentiate monorail systems from other transport modes, the Monorail Society further clarifies the definition of a monorail such that the beam in a monorail system is narrower than the vehicle.

Similarities

Monorails are often but not exclusively elevated, sometimes leading to confusion with other elevated systems such as the Docklands Light Railway, Vancouver SkyTrain and the JFK AirTrain. Monorail vehicles are often at first glance similar to other light rail vehicles, and can be both manned and unmanned. Monorail vehicles can also be found in singular rigid format, articulated single units, or as multiple units coupled into 'trains'. In common with other advanced rapid transit systems, some monorails are driven by linear induction motor. In common with other dual rail systems, the vehicle bodies are connected to the beam via bogies, allowing curves to be negotiated.

Differences

Unlike some trams and light rail systems, modern monorails are always partitioned from other traffic and pedestrians. Monorails are both guided and supported via interaction with the same single beam, in contrast to other guided systems such as Rubber-tyred metros, such as the Sapporo Municipal Subway; or guided buses or trams, such as Translohr. Monorails also do not use pantographs.

Maglev

Under the Monorail Society beam width criteria, some but not all maglev systems are considered monorails, such as the Transrapid and Linimo. Maglevs differ from all other monorail systems in that they do not (normally) physically contact the beam.

History

Early years

Attempts at creating monorail alternatives to conventional railways have been made since the early part of the 19th century. The earliest patent was taken out by Henry Palmer in the UK in 1821, and the design was employed at Deptford Dockyard and a short line for moving stone from a quarry near Cheshunt to the River Lea.

Early designs centred on use of a double-flanged single metal rail alternative to the double rail of conventional railways. Wheels on this rail would both guide and support the monorail car. A surviving suspended version is the Wuppertal monorail. Into the 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. One of the first systems put into practical use was that of French engineer Charles Lartigue, who built a monorail line between Ballybunion and Listowel in Ireland, which was opened in 1888 and closed in 1924 (due to damage from Ireland's Civil War). The Lartigue system uses a load-bering single rail and two lower, external rails for balance, the three carried on triangular supports.