guided bus

Guided buses are buses capable of being steered by external means, usually on a dedicated track or roll way that excludes other traffic, permitting the maintenance of schedules even during rush hours. Unlike trolleybuses or rubber-tired trams, for part of their routes guided buses are able to share road space with general traffic along conventional roads, or with conventional buses on standard bus lanes.

Guidance systems can be physical, such as kerbs or guide bars, or remote, such as optical or radio guidance.

Guided buses may be articulated, allowing more passengers, but not as many as light rail or trams that do not also freely navigate public roads.

History

Precursors

The kerb-guided bus (KGB) guidance mechanism is a development of the early flangeways, pre-dating railways. The Gloucester and Cheltenham Tramroad
of 1809 therefore has a claim to be the earliest guided busway. There were earlier flangeways, but they did not carry passengers.

Modern examples

There are a few examples of guided buses around the world constructed since 1980.

The first modern guided busway system was opened in 1980 in Essen, Germany. This was initially a demonstration track, but it was periodically expanded and is still in operation as of 2019.

The first guided busway in the United Kingdom was in Birmingham, the Tracline 65, long, experimentally in 1984. It closed in 1987.

Based on the experience in Essen, in 1986 the Government of South Australia opened the O-Bahn Busway in Adelaide. This is a 12-kilometre guided busway.

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 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 It was discontinued, as the majority of buses fitted with guide wheels were withdrawn for age reasons.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.

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

The Cambridgeshire Guided Busway between Cambridge and St Ives, at , is the world's longest guided busway.

Between 2004 and 2008, a section of guided busway was in operation between Stenhouse and Broomhouse in the west of Edinburgh.The route was later converted for use by Edinburgh trams.

Rubber-tyred trams

Guided buses are to be distinguished from rubber-tyred systems that cannot run other than along a dedicated trackway, or under fixed overhead power lines.

Guidance systems

Optical guidance

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

Optical guidance is a means of approaching light rail performance with a fast and economical set-up. It enables buses to have precision-docking capabilities as efficient as those of light rail and reduces dwell times, making it possible to drive the vehicle to a precise point on a platform according to an accurate and reliable trajectory. The distance between the door steps and the platform is optimized not to exceed . Level boarding is then possible, and there is no need to use a mobile ramp for people with mobility impairments.

The Optiguide system, an optical guidance device developed by Siemens Transportation Systems, has been in revenue service since 2001 in Rouen and Nîmes (only at stations), France, and has been fitted to trolleybuses in Castellon (Spain) since June 2008.

Another system was introduced in 2017. Called Autonomous Rail Rapid Transit (ART) and developed by CRRC, it uses optical systems to follow markers on a roadway. The ART system is frequently referred to as a "trackless tram" and occasionally as an "optically-guided bus".

Magnetic guidance

Other experimental systems have non-mechanical guidance, such as sensors or magnets buried in the roadway. In 2004, Stagecoach Group signed a deal with Siemens to develop an optical guidance system for use in the United Kingdom.

Two bus lines in Eindhoven