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A bi-articulated bus or double-articulated bus is a higher-capacity type of articulated bus. It is an extension of a conventional or single-articulated bus, in that it has three passenger compartment sections instead of two. This also involves the addition of an extra axle and a second articulation joint. Due to the extended length, bi-articulated buses tend to be used on high-frequency core routes or bus rapid transit schemes rather than conventional bus routes.
One of their main advantages is that they reduce the number of drivers needed to run a service for a specific number of people — i.e., it is usually much more cost-efficient to run a bi-articulated bus with one driver, than, for example, to run two smaller rigid buses providing the same total number of seats.
Disadvantages include some difficulties in traffic, the need to have bus stops catering to the extended length, and the fact that two buses with the same capacity can be used more flexibly, such as having one bus arrive every five minutes, instead of one of the larger articulated buses every ten minutes (as an example providing the same service capacity, but different frequencies).
Early versions 
The French manufacturers Renault and Heuliez Bus developed the "Mégabus" (officially the Heuliez GX237), a bi-articulated high-floor bus, in the late 1980s. The demonstrator Mégabus visited transit agencies throughout France, but the only city to order them was Bordeaux (an order of 10 buses, built in 1989). These buses, now retired, operated Bordeaux's bus route 7 (the most heavily used route in Europe) until the city's Tramway de Bordeaux was built in 2004.
Currently in use models 
The transit system that has used bi-articulated buses the longest is the Rede Integrada de Transporte, in Curitiba, Brazil, which provides a type of service that has come to be known – particularly in American English – as bus rapid transit (BRT), where buses run in dedicated lanes and stop only at enclosed stations. Use of bi-articulated buses began in 1992, with vehicles manufactured by Volvo (chassis) and Marcopolo/Ciferal (body), able to carry up to 270 passengers. Each bi-articulated bus is equipped with five doors where passengers can quickly load and unload. Buses stop only at enclosed, tube-shaped stations, where passengers pre-pay the fare and then board at the same level as the vehicle floor. Curitiba has over 170 bi-articulated buses in operation on routes serving five main corridors of dedicated bus lanes. These buses run on an average frequency of 50 seconds during peak hours.
The Brazilian bus body manufacturers Marcopolo, CAIO, Busscar and most lately Neobus have made many bi-articulated buses on top of Volvo chassis. They are currently used in São Paulo, Campinas, Goiânia and Curitiba.
Volvo has manufactured several bi-articulated buses now in use in Gothenburg. They are based on Volvo's "pusher"-type articulated, low-floor bus model with the internal combustion engine mounted on the floor on the side of the bus, and the cooling system on the roof.
The Belgian manufacturer Van Hool offers a 25 metres (82.0 ft) bi-articulated bus with a capacity of about 180 passengers. In September 2002, fifteen were deployed on lines 11 and 12 in the Dutch city of Utrecht, connecting the downtown railway station to office, college and university buildings at the edge of the city. Twelve more have been added since. These buses are also used in the German cities of Aachen (lines 5 and 45) and Hamburg (Metrobus 5 and Eilbus E86), where single-articulated buses alone were not able to handle the huge number of passengers per day.
Swiss manufacturer Hess produces a bi-articulated trolleybus called LighTram that is in use in several Swiss cities, including Zürich, Geneva and Lucerne. Also, a bus with a hybrid engine based on the LighTram is offered. This type is currently in use for the Luxembourgian bus operator Voyages Emile Weber.
In-development projects 
The Chinese manufacturer Zhejiang Youngman (Jinhua Neoplan) has developed the 25 metres (82.0 ft) JNP6250G bi-articulated bus, deemed the "world's largest", with assistance from NEOPLAN Bus GmbH. These buses are on trial service in Beijing.
See also 
- [dead link]
- "Autobusové Noviny". Retrieved 2010-11-12.
- Bushell, Chris (ed.) (1993). Jane's Urban Transport Systems 1993-94, pp. 79–80. Coulsdon, Surrey (UK): Jane's Information Group. ISBN 0-7106-1072-6.
- "Geschiedenis in vogelvlucht" (in Dutch). Het GVU - Openbaar Vervoer in Utrecht en omgeving. Archived from the original on 6 February 2007. Retrieved 2007-01-07.
- "News archive for Luxembourg" (in German). stadtbus.de. Retrieved 2010-09-27.
- article in Shanghai Daily - 'World's largest' bus debuts in Shanghai By Kat Jiang 2007-3-14
|Wikimedia Commons has media related to: Bi-articulated buses|
- Photo of an early Van Hool AGG300
- Image gallery of Volvo BRT systems, some bi-articulated
- Details of the Renault Heuliez Mégabus
- Press release about introduction of Volvo bi-articulated buses in Gothenburg, Sweden