Bi-articulated bus

Curitiba's bi-articulated Volvo B12M under a Neobus body running with 100% biofuel. At 28 metres, it is one of the world's longest buses. Take note of the train-like doors on each section for rapid exchange of people.

A Busscar bi-articulated in Bogota, Colombia.

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.

Design Considerations

Although buses can be designed any way regardless of the number of articulations, common bi-articulated bus designs resemble railway lines -- in terms of how it operates -- more than standard buses; in particular, considerations such as rapid passenger entry/exit (train type doors -- usually elevated) vs the traditional bus doors (with steps, including kneeling bus) often found on extra long traditional buses. By pushing payment issues (and their delays) to a BRT bus station, and physically separating paid passengers by fare gates, and eliminating passenger or bus vertical movement to get on/off the bus, it frees the conductor from delays and complications, increasing throughput, speed, and schedule reliability. The trade-off however is the cost of building bus stations vs simply a marking or pole to indicate where stops are. Other issues include turning radius and drive control.

An additional advantage is that they reduce the number of drivers needed to run a service for a specific number of people — i.e., for areas with relatively high labor costs, it is usually much more cost-efficient to run bi-articulated bus with one driver over running two smaller rigid buses providing the same total number of seats. For traditional buses routes without stations and with driver managed payment systems, this is the biggest advantage.

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), or covering for other existing bus routes.

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 tram system was built in 2004.^[1]

Hungarian bus manufacturer Ikarus also developed a bi-articulated bus prototype, the Ikarus 293, in the early 1990s.^[2]

Models currently in use

A Van Hool bi-articulated bus in Hamburg, Germany

AutoTram Extra Grand

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,^[3] 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 period 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 Rio de Janeiro, São Paulo, Campinas, Goiânia, Curitiba and Bogotá.

Volvo has manufactured several bi-articulated buses now in use in Gothenburg. They are based on Volvo's "puller"-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.^[4] 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.^[5]

In 2012 Fraunhofer IVI introduced the Autotram Extra Grand in Dresden.^[6][7] With overall length of 30.73 metres (100.8 ft) it is the longest bus in service with a passenger capacity of 256. It's unique 5-axle design is made possible using advanced computer controlled steering on the 3 trailing axles.

In-development projects

The Chinese manufacturer Zhejiang Youngman (Jinhua Neoplan) has developed a 300-passenger,^[8] 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.^[9]

Bogotá's BRT system TransMilenio is currently operating bi-articulated for its most crowded corridors.

See also

• List of buses
• Trailer bus
• Road train

References

External links

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
  • showing the articulation better
• Youngman-Neoplan China (Flash + JavaScript)