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This article is about high-capacity bus transit systems. For lower-capacity transit systems, see share taxi and bus; for rail transit systems see tram, light rail and rapid transit.
Bus rapid transit (BRT) is a term applied to a variety of public transportation systems that use buses to provide a service that is of a higher speed than an ordinary bus line. Often this is achieved by making improvements to existing infrastructure, vehicles and scheduling. The goal of these systems is to approach the service quality of rail transit while still enjoying the cost savings of bus transit. The expression BRT is mainly used in North America; in Europe and Australia, it is often called a busway, while elsewhere, it may be called a quality bus.
[edit] EtymologyBus rapid transit takes part of its name from rapid transit which describes a high-capacity transport system with its own right-of-way, its alignment often being elevated or running in tunnels, and typically running long trains at short headways of a few minutes. BRT encompasses a broad variety of modes, including those known or formerly known as express buses, limited busways, rapid busways, and BHNS in France (Bus à Haut Niveau de Service). Typical transit speeds of BRT systems range from 7 to 25 miles per hour which can compare with surface running LRT.[1] [edit] Main featuresThese bus systems can come in a variety of forms, from dedicated busways that have their own rights-of-way (e.g., the Ottawa Transitway or the Pittsburgh MLK East Busway) to bus services that utilize HOV lanes and dedicated freeway lanes (e.g., Honolulu's CityExpress) to limited stop buses on pre-existing routes. An ideal bus rapid transit service would be expected to include most of the following features:
Acceptance of BRT may increase using trolley-buses, because of the lower gaseous and noise emissions. The price penalty of installing overhead lines can be repaid over a longer period by the savings from centrally generated electricity[citation needed]. [edit] Comparison with other forms of mass transit
BRT attempts to combine the advantages of a metro system (noticeably right-of-way which improves punctuality and frequency) with the advantages of a bus system (low construction and maintenance costs, low vehicle costs, right-of-way not required for entire length, and if catered for the ability for feeder bus services to join a trunk busway). Compared to standard bus service, BRT systems with dedicated right-of-way lanes, and thus an increased average vehicle speed, can provide more passenger miles with the same number of vehicles and personnel. They also bring about a smoother ride than a normal bus immersed in stop-and-go traffic. It is overly simplistic to use calculations to predict the capacity of BRT and normal buses and say typical buses are 12 metres (40 feet) long, articulated buses 18 metres (60 feet).[clarification needed] The maximum length for a street-running tram (in Germany) is 75 meters (about 250 feet). Light rail systems running in-street are limited to one city block in length, unless (as in Sacramento, CA) they are allowed to obstruct intersections when stopped. Metro trains can be 240 m (about 800 feet) long. With similar dwell times in stations the capacity of rail systems would scale with the length of the train. For instance, a light rail system running on two-minute headways with 200-passenger cars operating as single units could carry 6,000 passengers per hour. It should theoretically therefore carry 12,000 passengers per hour with two-car trains, and 24,000 per hour with four-car trains. In practice real world delays multiply and headways become disrupted causing a practical limitation of around 12,000 to 19,000[2] However, the Transmilenio system in Bogotá, reports to carry 2'850.000 passengers per day on average, including feeder lines.[3] This would put it in 8th place in the world list of Metro systems by annual passenger rides. Transmilenio, during 2008, is in its third of seven projected construction phases. The Transportation Research Board reports that the 388 kilometer complete system is projected to cost U$3.3 billion, which is only 10 percent more than a previously proposed Metro of 30 kilometers would have cost. [edit] Comparison with light railStudies that count individual passengers by observation is a notable source of information regarding capacity. A survey [1] by the UK Transport Research Laboratory revealed: Exhibit 3-22: Maximum Observed Peak Hour Bus Flows, Capacities, and Passenger Flows at Peak Load Points on Transitways Measured Peak Hour Passenger Flow (Passengers / Hour) Designated Lane: Ankara, Istanbul, Abidjan 7,300 – 19,500 Designated Lanes with Feeders Curitiba, Brazil 13,900 – 24,100 Designated Lanes with Bus Ordering (Travelling in Clusters) Porto Alegre 17,500 – 18,300 Designated Lanes with Overlapping Routes, Passing at Stations and Express Routes Belo Horizonte, São Paulo 15,800-20,300 Transmilenio, Bogotá 35,000-40,000 [4] However, many BRT systems such as OC Transpo Transitway, Ottawa and South-East Busway, Brisbane are based on multiple bus routes sharing a common dedicated busway to bypass congestion, especially to/from a central business district. In this form, the BRT system passenger capacity is limited by vehicle capacity times vehicle headway of the busway. As buses can operate at headways as low as 10 seconds between vehicles (compared to at least one minute headways for rail vehicles), actual busway capacity can reach passenger rail capacities. At the high end, the Lincoln Tunnel XBL bus lane carries 62,000 commuters in the 4 hour morning peak, more than any Light Rail Line. However, this lane has no stops in it. Stops increase the headway and limit a BRT lane to about 10,000 passengers per hour, even with passing lanes in the stations. Note that this is still five times the number carried in the automobiles in a congested freeway lane. At its busiest point, Brisbane's South-East Busway currently carries in excess of 15,000 commuters per hour per direction, and is not yet considered at capacity. Many agencies make a clear distinction between a pure BRT, which is in exclusive lanes, and a more compromised form in mixed traffic. For example, the Los Angeles Orange Line runs entirely in an exclusive lane and therefore achieves speed and reliability comparable to rail. Because it is functionally equivalent to rail, the Los Angeles County Metropolitan Transportation Authority presents this line as part of its rail transit system, distinct from its "Rapid" lines, which run in mixed traffic. The typical diesel engine on the bus causes noticeable levels of air pollution, noise and vibrations. Through developing buses as hybrid vehicles and the use of new forms of trolleybus BRT designers hope to increase ride quality and decrease pollution. As the energy use for acceleration is proportional to the vehicle mass, electric traction allows lighter vehicles, faster acceleration and energy that can be fed back into batteries or the grid through regenerative brakes. Regenerative braking is standard on modern rail systems. In contrast to BRT, both Light Rail and rapid transit require the placement of rails for the whole line. The tram usually avoids the high additional costs for the engineering structures like tunnels that need to be built for metros. Rail tends to provide a smoother ride and is known to attract significantly higher passenger numbers than road-based systems. Many BRT designers have used the need to construct power conduit systems as an argument against Light Rail, but a new proposal, known as ultra light rail, would have trams carry their own power, much like a bus, at a significant energy savings due to lack of rolling resistance. In larger towns and cities, such as Essen, Germany, Pittsburgh, U.S., and Seattle, U.S. it is common for a right of way exclusive to public transport to be used by both light rail and buses. [edit] In tunnels or tunnel systemsA special issue arises in the use of bus vehicles in metro structures. Since the areas where the demand for an exclusive bus right-of-way is apt to be in dense downtown areas where an above-ground structure may be unacceptable on historic, logistic, or environmental grounds, use of BRT in fully underground tunnels may not be avoidable. Since buses are usually powered by internal combustion engines, bus metros raise ventilation issues similar to those of tunnels. In the case of tunnels, powerful fans typically exchange air through ventilation structures on the surface, but are usually placed in a location as remote as possible from occupied areas to minimize the effects of noise and concentrated pollution. A straightforward way to deal with this is to use electrical propulsion in tunnels and, in fact, Seattle in its Metro Bus Tunnel and Boston in Phase II of its Silver Line are using this method in their respective BRTs. In the case of Seattle, dual-mode (electric/diesel electric) buses manufactured by Breda were used until 2004, with the center axle driven by electric motors obtaining power from a trolley wire through a trolley pole in the subway, and with the rear axle driven by a conventional diesel powertrain on freeways and streets. Boston is using a similar approach, after initially using electric trolleybuses to provide service pending delivery of the dual mode vehicles in 2005. In 2004, Seattle replaced its "Transit Tunnel" fleet with diesel-electric hybrid buses, which operate similarly to hybrid cars outside the tunnel and in a low-noise, low-emissions "hush mode" (in which the diesel engine operates but does not exceed idle speed) when underground. The necessity for providing electric power in these environments brings the capital and maintenance costs of such routes closer to light rail and raises the question of building light rail instead. In Seattle, the downtown transit tunnel was retrofitted for conversion to a shared hybrid-bus and light-rail facility in preparation for Seattle's Central Link Light Rail line, which opened in July 2009. Between 1988 and 1995 dual mode buses provided a shared service with the steel wheel streetcars / trams through part of the light rail tunnel system in the German city of Essen. Whilst underground the buses fully interacted with the railway-style signalling system. Initially they called at just one underground station but after the 1991 opening of a tunnel extension they started calling at an additional two subterranean stations. The new stations featured island platforms for which the buses were equipped with two sets of passenger doors on their otherside. For safety the buses in Essen also used the guided bus system so that whilst travelling through the narrow tunnels the bus driver did not need to steer the vehicle. Although the bus driver will normally sell tickets to boarding passengers who need them, when calling at the underground stations the off-vehicle ticketing system was enforced, with passengers needing to purchase their tickets before descending to the platforms. [edit] Aesthetics of Bus Rapid TransitBus rapid transit vehicles, station stops, and collateral elements are typically free of advertising (which is common to many public transit systems). This is not always the case, however: Los Angeles County Metropolitan Transportation Authority (Metro), has video advertising on board the buses. Other transit agencies seem to use this space to "brand" BRT service, and to communicate desirable elements about the service (speed, efficiency, etc.). Pioneering research has been conducted by two American researchers about how Bus Rapid Transit brands are applied, and how BRT systems are visually identified.[5] [edit] Think Tanks and BlogsThere are at least three think tanks directly involved in lobbying for BRT systems: 1) The National Bus Rapid Transit Institute was established by the US Federal Government in January of 1991, and is housed at the Center for Urban Transportation Research (CUTR) at the University of South Florida, and 2) the Bus Rapid Transit Policy Center is another think tank that promotes BRT technology over light rail, and 3) the Institute for Transportation and Development Policy. The objectivity of the work of CUTR and at least one of its employees has been questioned. [6] The World Resources Institute and the CityFix series of blogs, funded by EMBARQ (whose funders include the Shell Foundation), also issue frequent reports that support BRT. The Streetsblog.org series of blogs and Streetfilms.org videoblog also are frequent proponents of BRT. [edit] Bus Rapid Transit Planning GuideIn June of 2007, the Institute for Transportation and Development Policy (ITDP) published the BRT Planning Guide with support from the United Nations Environment Programme, the Deutsche Gesellschaft für Technische Zusammenarbeit, the Hewlett Foundation, and Viva Cities. The guide, co-authored by Walter Hook of ITDP and Lloyd Wright of Viva Cities, draws from the extensive BRT design experience of Latin American transit planners, and aims to disseminate this information in cities looking to design and implement BRT systems of their own.[7] The guide is currently available in English, Portuguese, and Chinese, and is free for download in .pdf format from ITDP's website.[8] [edit] List of systemsMain article: List of bus rapid transit systems [edit] Implementation by countryMain article: Implementation of bus rapid transit by country [edit] See also Double articulated bus in Hamburg, Germany.
[edit] References
Developing Cities, Transport and Road Research Laboratory Research Report 329, Department of Transport, Crowthorne, Berkshire, United Kingdom, 1991 [edit] External links
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