An articulated bus (either a motor bus or trolleybus) is an articulated vehicle used in public transportation. It is usually a single-decker, and comprises two or more rigid sections linked by a pivoting joint (articulation) enclosed by protective bellows inside and outside and a cover plate on the floor. This allows a longer legal length than rigid-bodied buses, and hence a higher passenger capacity, while still allowing the bus to maneuver adequately.
Used almost exclusively on public transport bus services, articulated buses are approximately 18 m or 60 ft in length; whereas standard rigid buses are usually 11 to 14 m or 30 to 40 ft long. The common arrangement of an articulated bus is to have a forward section with two axles leading a rear section with a single axle, with the driving axle mounted on either the front or the rear section. Some articulated buses have a steering arrangement on the rearmost axle which turns slightly in opposition to the front steering axle, allowing the vehicle to negotiate tighter turns, similar to hook-and-ladder fire trucks operating in city environments. A less common variant of the articulated bus is the bi-articulated bus, where the vehicle has two trailer sections rather than one. Their capacity is around 200 people, and their length is about either 25 meters or 80 feet; as such, they are used almost exclusively on high-capacity, high-frequency arterial routes and on bus rapid transit services.
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Early examples of the articulated bus appeared in Europe in the 1920s. In 1938, Twin Coach built an articulated bus for the city of Baltimore; this bus, which had four axles on a 47 ft (14 m) long body, was only articulated in the vertical direction to accommodate steep grades. 15 examples of the "Super Twin" were built in 1948, but it was not developed further. According to contemporary coverage, the Super Twin had a capacity of 58 seated and 120 total, with a weight of 27,500 lb (12,500 kg).
In Budapest, the first prototypes of the Ikarus 180 (named for its 180-passenger capacity) were shown in 1961. There is an ongoing exhibition in Budapest at the Hungarian Technical and Transportation Museum in 2010 with the title "The articulated bus is 50 years old." The Ikarus 180 went into limited production in 1963, and entered serial production in 1966; the Ikarus 180 was discontinued in 1973 when its successor, the Ikarus 280 was released.
In the mid-1960s, AC Transit in California pioneered the American use of a modern articulated bus, operating the experimental commuter coach "XMC 77" (based on Continental Trailways' Bus & Car Co. Super Golden Eagle model) on some of its transbay lines. The XMC-77, which AC Transit dubbed the "Freeway Train", was originally built in 1958, purchased by the District in October 1965, and made its debut run for Line N on March 14, 1966; passengers on the inaugural run were presented with special souvenir tickets. XMC-77 was later exhibited to the public at various locations in the East Bay and the Transbay Terminal. It offered seats for 77 passengers (finished in brown and orange) and an observation lounge, complete with a card table to seat a quartet. The 60 ft (18.3 m) long coach stood 10 ft 10 in (3.30 m) high and was powered by a Cummins engine with an output of 262 hp (195 kW). Engineering for the XMC-77 was carried out by the local firm of DeLeuw Cather & Co.
In the United States, articulated buses were imported from Europe and deployed in the late 1970s and early 1980s. During this time, rising operating costs led to public takeovers of transit systems, and the pressure to reduce labor (driver) costs in turn meant transporting more passengers in a single vehicle. King County Metro and Caltrans led a Pooled Purchase Consortium, formed in 1976, which later awarded a contract to the AM General/M.A.N. joint venture responsible for assembling MAN SG 220 (from Germany) articulated buses in America. Contemporaneously, Crown entered an agreement with Ikarus to produce the Crown-Ikarus 286, coupling American-made powertrains with the Hungarian Ikarus 280 chassis.
Articulated buses have also been used in Australia, Austria (Gräf & Stift), Italy, Germany (Gaubschat, Emmelmann, Göppel, Duewag, Vetter), Canada (LFS Articulated), Hungary (Ikarus), Poland (Jelcz AP02)) The first modern British "bendy buses" (as they are referred to in the UK and Canada) were built by Leyland-DAB and used in the city of Sheffield in the 1980s. They were subsequently withdrawn from service because they proved to be expensive to maintain.
Advantages and disadvantagesEdit
The main benefits of an articulated bus over the double-decker bus are rapid simultaneous boarding and disembarkation through more and larger doors, somewhat larger passenger capacity (94-120 versus 80−90), increased stability arising from a lower centre of gravity, smaller frontal area giving less air resistance than double decker buses thus better fuel efficiency, often a smaller turning radius, higher maximum service speed, the ability to pass under low bridges, and improved accessibility for people with disabilities and the elderly.
During late 2003 and early 2004, a series of onboard fires on newly delivered Mercedes-Benz Citaros led to Londoners humorously nicknaming the vehicles chariots of fire. Mercedes-Benz quickly addressed the problem, although the vehicles were out of service for a period. However, no overheating or fire-related incidents have ever been recorded in Vancouver's articulated electric trolley buses from a similar cause. Vancouver's articulated trolley buses were specifically chosen for the higher torque output of their electric motors, which typically outperform diesel-based low-floor buses.
In some circumstances of urban operation (such as in areas with narrow streets and tight turns), articulated buses may also be involved in significantly more accidents than conventional buses. Estimates for London's articulated buses put their involvement in accidents involving pedestrians at over five times the rate of all other buses, and over twice as high for accidents involving cyclists. In a period when articulated buses made up approximately 5% of the London bus fleet, they were involved in 20% of all bus-related deaths, statistics which eventually led to their replacement. However, these safety statistics may be partly skewed due to the buses having been used on the busiest routes in the most crowded areas of the city, making them look worse than the buses they were being compared with.
An articulated bus is a long vehicle and usually requires a specially trained driver, as maneuvering (particularly reversing) can be difficult. Articulated electric trolleybuses can be difficult to control, with their motors producing momentary peak power in excess of 600 kilowatts (816 PS; 805 hp). The trailer section of a "puller" bus can be subject to unusual centripetal forces, which many people can find uncomfortable, although this is not an issue with "pushers". Nonetheless, the articulated bus is highly successful in Budapest, Hungary, where the BKV city transit company has been operating more than 1000 of them every day since the early 1970s. The Hungarian company Volán also runs hundreds of articulated buses on intercity lines.
Articulated buses have been used in most European countries for many years. Articulated buses became popular in mainland Europe due to their increased capacity compared with regular buses. In many cities, lower railway bridge clearances have precluded the use of double-deck vehicles, which have never achieved great popularity there. Overhead wires for trams, trolleybuses, etc. are not really relevant issues, as the minimum normal clearance above road level is standard across the EU and is well in excess of the height of a double-deck vehicle—otherwise, many freight vehicles would encounter severe problems in the course of normal operation.
From 3 July 2011 to 28 August 2013, articulated Mercedes Citaro buses purchased from London have been used in Malta by the company Arriva on a number of routes across the country. A number of serious engine fires resulted in their withdrawal from service, and they have also been responsible for causing an increase in traffic congestion and accidents involving pedestrians and cyclists.
Until 1980, articulated buses were illegal on the UK's roads. A 1979 experiment by South Yorkshire Passenger Transport Executive with buses manufactured by MAN and Leyland-DAB led to a change in the law, but the experiment was abandoned in 1981 because double-decker buses were generally considered less expensive both to purchase and to operate. The cost and weight of the strengthened deck framing and staircase of a double-decker was lower than the cost and weight of the additional axle(s) and coupling mechanism of an articulated bus. Modern technology has reduced the weight disadvantage, and the benefits of a continuous low floor allowing easier access plus additional entrance doors for smoother loading have led to reconsideration of the use of articulated buses in the UK.
In London, articulated buses were used on some routes from 2001 until 2011, but they were not a success. Boris Johnson, former Mayor of London, promised in the run-up to the mayoral election of 2008 to rid the city of the controversial buses and replaced them with double deckers.
Elsewhere in the UK, they are generally operated on particular routes in order to increase passenger numbers, rather than across entire networks. With unsupervised “open boarding” through three doors and the requirement for pre-purchase of tickets, levels of fare-dodging on the new vehicles were found to be at least three times higher than on conventional buses where entry of passengers is monitored by the driver or conductor. The only way of checking for free riders was to use large teams of ticket inspectors to swamp the bus and inspect all tickets while keeping the doors closed, meanwhile delaying the further progress of the bus. Since the articulated buses were tending to serve areas of relative deprivation it is suspected that this was a contributory factor in Transport for London (TfL) turning against the concept.
In Israel, the use of articulated buses—commonly called long buses—is widespread, particularly in Gush Dan and Jerusalem, the two great urban centers of the country. The long buses are considered reliable and useful, and have been in service in Israel since the mid-1970s. During the Israeli–Palestinian conflict, such buses were often targeted by Palestinians and suicide bombers during rush hours, since a crowded long bus can contain more than 100 passengers. Due to the al-Aqsa Intifada wave of mass bombings, security measures were enforced and today many long buses in Israel are accompanied by a security guard.
In Asia, many major Chinese cities had fleets of articulated buses prior to the late 1990s. Some of these fleets have since been replaced by single-section units except in a few cities, namely Beijing, Shanghai, and Hangzhou. While in the 2000s a surge in BRT construction has reintroduced or re-purposed the articulated bus fleets for rapid transit usage in cities like Changzhou, Dalian, Guangzhou, Jinan, Kunming, Xiamen, Yancheng, Zaozhuang, and Zhengzhou.
Transjakarta, one of the longest BRT system in the world, has been using articulated buses manufactured by Scania for some of their busiest routes since 2015. Prior to Scania buses introduction, there were Chinese-made Huanghai, Zhong Tong, Yutong, Ankai, and local-made INKA Inobus and AAI Komodo buses already in-service for several years.
In Singapore, articulated buses were first introduced in 1996 by Trans-Island Bus Services (now SMRT Buses) with the Mercedes-Benz O405G buses (bodied in Hispano Carrcera (MK1/MK2), Hispano Habit and Volgren CR221L). They were withdrawn completely after July 2014. Bus services 61, 67, 106, 180, 189, 190, 851, 960, 962, 963, 964 and 969 have ceased their usage of bendy buses. SMRT's newest MAN NG363F bendy buses were still in use today.
Articulated buses are commonplace in such US urban centers as Akron, Baltimore, Boston, Cleveland, Minneapolis-St.Paul, Miami, Orlando, Chicago, Denver, Houston, Indianapolis, Los Angeles, New York City, Orange County (California), Pittsburgh, Philadelphia, Phoenix, the Quad Cities, Rochester, San Diego, San Francisco, Seattle, Disney World, Orlando, FL. and Washington, D.C.. In Eugene, Lane Transit District uses articulated buses on some high-traffic routes, as well as on their Emerald Express (EmX) Bus Rapid Transit Service.
In Canada, they are used in Brampton, Calgary, Edmonton, Halifax, Hamilton, London, Longueuil, Mississauga, Montreal, Niagara Falls, Ottawa, Quebec City, Saskatoon, Toronto, York Region, Metro Vancouver and Winnipeg.
In Adelaide, Australia, articulated buses are used on the O-Bahn Busway, reaching speeds of 100 km/h. The first articulated buses to use it were the Mercedes-Benz O305G buses; however, three MAN SG280H buses are also equipped for O-Bahn use. In recent years, it has proven problematic to find suitable low-floor articulated buses to replace the 1984-manufactured Mercedes buses, because the design of the O-Bahn track unfortunately precludes the use of most modern articulated buses. Sydney, Australia has seen the operation of articulated buses for many years. Currently it operates a fleet of various models with eighty Volvo B12BLEA buses joining the Sydney Buses fleet in 2005 and 2006, increasing capacity along many of the busy corridors. A number of prototype vehicles were delivered in 2008 & 2009 to operate on Sydney Buses' first Metrobus route, the M10 from Leichhardt to Kingsford and Maroubra Junction. The buses feature different chassis, body types, and internal layouts. The articulated Volvo B12BLEA buses are fully wheelchair-accessible, air-conditioned, and have visual and audible next-stop passenger information systems installed. The buses feature air-conditioning, large electronic destination displays and cloth seating. Additionally, each bus features a stepless entry, which will assist less-mobile passengers. Flip-up seats in the front part of the bus allow easy accommodation for passengers in wheelchairs and with strollers and prams. In 2009-2010 150 new Volvo B12BLEA articulated buses have been introduced into the Sydney Buses fleet, many of these part of the expanded Metrobus program.
Articulated buses can be of "pusher" or "puller" configuration. Very few companies specialise in manufacturing the articulated section for the buses. One that does is ATG Autotechnik GmbH in Siek near Hamburg.
In most puller articulated buses, the engine is mounted under the floor between the front and middle axles, and only the middle axle is powered. Some consider this an outdated design, as it prohibits floor levels lower than approximately 750 millimetres (30 in), and can produce passenger discomfort due to high noise and vibration levels. On the other hand, they can be used in very narrow or severely potholed streets. This type of bus also performs better in snowy or icy conditions, as the thrust from the driving wheels does not cause the vehicle to jacknife. Newer models such as the Van Hool AG300 feature low floor while maintaining the puller design placing the engine block off-center opposite to the second door. Also, the unpowered rear axle is much simpler and carries no engine weight, facilitating the installation of counter-steering mechanisms to further decrease the turning radius.
A typical puller model is the Hungarian-made Ikarus 280, the articulated version of the Ikarus 260, of which 60,993 buses were manufactured between 1973 and 2002, mostly for Soviet bloc customers. (This type accounted for two-thirds of the articulated buses built in the 1970s.) Puller-type articulated buses are built in less numbers, but are still available in Scandinavia and South America. Examples being the Volvo B9S and Volvo B12M.
The pusher bus needs a damping system in the joint to reduce the risk of jack-knifing and fishtailing. This was developed by the FFG Fahrzeugwerkstätten Falkenried in Germany. The production cost of the pusher bus was lower than that of a puller bus. The puller bus was a completely different construction compared to a solo bus which was often fabricated by external body construction firms due to the lower production numbers compared to solo buses. The pusher concept enabled the bus manufacturer to simply join a forward and a rear part of a solo bus and build the articulated bus completely in-house. This reduced the production cost.
In pusher buses, only the rear axle is powered by a rear-mounted internal combustion engine, and the longitudinal stability of the vehicle is maintained by active hydraulics mounted under the turntable. This modern system makes it possible to build buses without steps and having low floors along their entire length, which simplifies access for passengers with limited mobility.
Modern low-floor pusher articulated buses also tend to suffer from suspension problems because their wheels lack sufficient travel to enable them to absorb typical road surface unevenness. This also leads to passenger discomfort and relatively rapid disintegration of the vehicle's superstructure.
Makers of pusher-type articulated buses include Mercedes-Benz, New Flyer Industries, MAN, Volvo and Scania. The Renault PR 180 and PR 180.2 (articulated versions of the PR 100 and PR 100.2) were a special variation of the pusher design in which both the middle and the rear axles were driven, with a driveshaft passing through the turntable between the two driving axles.
Although the majority of articulated buses utilise diesel engines for their motive power, a number of operators (primarily outside North America and by LACMTA) have adopted compressed natural gas (CNG) power in order to reduce pollution. Many other transit authorities in the United States and Canada are adopting articulated buses that are diesel-electric hybrids, such as the New Flyer DE60LF. There are also articulated trolleybuses, which use an overhead contact system to power electric traction motors.
Since the late 1980s, the concept of the articulated bus has been extended further with the addition of a second trailer section that extends the bus almost to tram length and capacity, to create a bi-articulated bus, called also triple bus. The Chinese manufacturer Zhejiang Youngman (Jinhua Neoplan) has developed the 25 metres (82 ft) JNP6280G bi-articulated bus, deemed the "world's largest", which will be used in Beijing.
Bi-articulated buses are still rare, having been trialled and rejected in some places. Because of their length they have a role on very high-capacity routes, or as a component of a bus rapid transit scheme. Major examples of bi-articulated buses playing a major role in bus rapid transit can be found in Curitiba, Bogota, Mexico City, Quito, Santiago de Chile, etc. Volvo is a major supplier of puller-type bi-articulated buses in these markets. In the Netherlands, bi-articulated buses came into service in Utrecht (2002) and Groningen (2014) on busy routes.
Double-decker articulated busesEdit
A few attempts have been made to design a double-decker articulated bus. NEOPLAN Bus GmbH built a handful of Neoplan Jumbocruisers between 1975 and 1992. In these models, only the upper deck allows movement between the two sections, so each section has its own doors and set of stairs.
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In some countries of the European Union, as well as in the United States and Canada, an articulated bus can be driven with the same license used to drive a rigid bus (D in Europe, B in the U.S.), while a bus towing a normal trailer requires a bus + trailer (D+E) license. However, special training is needed for bi-articulated buses.
In popular cultureEdit
In a campaign associated with the Transformers: Revenge of the Fallen film, a 2014 Transformers character was created using parts from an articulated bus with the actual vehicle as its intended alternate form and dubbed "Bendy-Bus Prime."
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