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Guided bus

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A bus on the O-Bahn Busway route in Adelaide
The guide wheel of a guided bus in Mannheim, Germany
A Fastway bus in the guided bus lane on Southgate Avenue, Crawley, UK

Guided buses are buses steered for part or all of their route by external means, usually on a dedicated track. This track, which often parallels existing roads, excludes all other traffic, permitting the maintenance of reliable schedules on heavily used corridors even during rush hours.

Guidance systems can be either physical, such as kerbs (in American and Canadian English, "curbs"), or remote, such as optical or radio guidance.

On kerb-guided buses (often abbreviated to KGB) small guide wheels are attached to the bus, and these engage vertical kerbs on either side of the trackway. The bus is steered in the normal way away from the guideway. The start of the guideway is funnelled from a wide track to the normal width. The trackway allows for high-speed operation on a narrow guideway as well as precise positioning at boarding platforms, facilitating access for the elderly and disabled.

History

Only a few examples currently exist, but more are proposed in various countries. The longest guided busway in the world is the O-Bahn Busway route in Adelaide, South Australia, which has been operating successfully since the mid 1980s.

The first guided busway in United Kingdom was in Birmingham, branded as Tracline 65, and had a short 600 metre length as an experiment in 1984. It has since been removed.[1] A number of guided busways have since been built or are planned in the United Kingdom - see List of guided busways and BRT systems in the United Kingdom.

In Mannheim, Germany from May 1992 to September 2005 a guided busway shared the tram alignment for a few hundred metres, which allowed buses to avoid a congested stretch of road in a location where there was no space for an extra traffic lane. It was discontinued as the majority of buses fitted with guide wheels were withdrawn for age reasons. There are no plans to convert newer buses.

Nagoya Guideway Bus in Nagoya, Japan, opened in March 2001, and is the only guided bus line in the country.

Rubber-tyred "trams"

A Translohr rubber-tyred "tram" for the future system in Padua, Italy
Bombardier Guided Light Transit in operation in Nancy, France

A further development of the guided bus is the "tramway on tyres", a rubber-tyred vehicle guided by a fixed rail in the ground, which draws current from overhead electric wires like a conventional tram.

Two incompatible systems exist, the Guided Light Transit designed by Bombardier Transportation, and the Translohr system. There are no guide bars on the sides but there is a central guidance rail that, in the case of Translohr, is a special rail that is grasped by a pair of metal guide wheels set at 45° to the road and at 90° to each other. In the Bombardier system a single double flanged wheel between the rubber tires follows the guidance rail. This is why the two systems are not compatible, however the shape of the groove of the double-flanged Bombardier guide wheel could possibly be adapted to the shape of the top of the Translohr guidance rail. In both cases the weight of the vehicle is borne by rubber tyres on bogies to which the guide wheels are attached. Power is supplied by overhead lines, or by rechargeable batteries in areas where there are no overhead wires.

  • Diagram of the Translohr central guide rail (green) and the vehicle's guide wheels (red), which grasp the rail perpendicular to each other.
    Diagram of the Translohr central guide rail (green) and the vehicle's guide wheels (red), which grasp the rail perpendicular to each other.
  • Cross section of guide rail and guide wheel of Bombardier's GLT.
    Cross section of guide rail and guide wheel of Bombardier's GLT.

The Bombardier system has been adopted in Nancy and Caen, France, while the Translohr system is in use in Clermont-Ferrand, France, and Tianjin, China, and is under construction in Padua, L'Aquila, and the mainland Mestre district of Venice in Italy. The Translohr system is intended for guidance-only operation, while the Bombardier system can be driven as a normal bus as requirements dictate, such as journeys to the depot. The Bombardier vehicles are legally considered buses, and must bear bus-like rear-view mirrors, lights and number plates. Unlike trams, GLT vehicles have a steering wheel, though it is not used when following the guidance rail. Because the Translohr "tram" cannot move without guidance it will probably not be classified as a bus. Hence the Translohr vehicles that on test runs on the Clermont-Ferrand network are not equipped with licence plates.

These systems offer a much more tram-like experience than a regular guided bus, and offer some advantages over trams, such as a potentially smaller turning radius, the ability to climb steeper gradients (up to 13%), and quieter running around corners. The infrastructure installation can be less complicated than the installation of a complete tram line in an existing street. These systems have been likened to the tram equivalent of rubber-tired metros, and they are also correspondingly less efficient than steel-wheeled light rail vehicles. There is no evidence to prove the superiority of either guidance system. Both Bombardier Guided Light Transit and Translohr have encountered derailment during operation [2] [3] .

Some commentators believe that rubber-tyred "trams" share the same problems of negative perception as other bus rapid transit systems.

Other experimental bus systems have non-physical guidance systems, such as sensors or magnets buried in the roadway [4] [5] . In 2004, Stagecoach Group signed a deal with Siemens AG to develop an optical guidance system for use in the UK.[6]

Optical Guidance

An optical guidance device on TEOR bus in Rouen.

Optical guidance relies on the principles of image processing. A camera located in front of the vehicle scans the bands of paint on the ground representing the reference trajectory. The signals obtained by the camera are sent to an onboard computer which compiles them with dynamic parameters of the vehicle (speed, yaw rate, wheels’ angle...). Thus, the calculator transmits commands to the guidance motor located on the steering column of the vehicle to control its trajectory in line with that of the reference.

Optical guidance is a mean to reach light rail performance with a fast and economic setting up. Indeed, optical guidance enables buses to have precision docking capabilities as efficient as of a light rail system and reduces dwell times. Indeed, optical guidance enables to drive the vehicle to the nearest of the platform according to a precise and reliable trajectory. The distance between the door steps and the platform is optimized in order not to exceed 2 inches. Access to the vehicle is then foot-level and the mobile ramp for people with mobility impairments becomes of no use.

In France, OPTIGUIDE, an optical guidance device developed by Siemens Transportation Systems SAS, has been in revenue service since 2001 on the Bus Rapid Transit system of Rouen (France). OPTIGUIDE has also been fitted on trolleybuses in Castellon (Spain) since June 2008 and will equip Bus Rapid Transit systems in Nîmes (France) and Bologna (Italy). OPTIGUIDE is adaptable on all types of buses (40 ft, 60 ft and 80 ft / diesel, hybrid, electric…).

See also

Examples of tram-like guided busways

Examples of guided busways

References

  1. ^ The former Birmingham (UK) Tracline 65 Kerb Guided Busway
  2. ^ "Further problems in Nancy". LRTA. November 20, 2002.
  3. ^ "The first modern guided tramway in China derails (国内首条现代导轨电车出轨)". news.qq.com. August 20, 2007.
  4. ^ New Era Hi-tech Buses
  5. ^ University of Berkley PATH Magnetic Guidance System - used on Snowploughs with trials including Transit Bus running and docking
  6. ^ "Stagecoach signs deal with Siemens to develop new bus optical guidance system". Stagecoach Group. December 8, 2004.
  7. ^ Cambridgeshire County Council - Guided Busway homepage
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