Articulated bus
An articulated bus, also referred to as a slinky bus, bendy bus, tandem bus, vestibule bus, stretch bus, or an accordion bus, is an articulated vehicle, typically a motor bus or trolleybus, used in public transportation. It is usually a single-decker, and comprises two or more rigid sections linked by a pivoting joint 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.
Due to their high passenger capacity, articulated buses are often used as part of bus rapid transit schemes, and can include a mechanical guidance system and electric bus or trolleybus.
Articulated buses are typically long, in contrast to standard rigid buses at 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 that 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. Such vehicles have a capacity of around 200 people, and a length of about ; as such, they are used almost exclusively on high-capacity, high-frequency arterial routes and on bus rapid transit services.
History
The first example of the articulated bus appeared in Milan, Italy, in 1937. In 1938, Twin Coach built an articulated bus for the city of Baltimore; this bus, which had four axles on a long body, was only articulated in the vertical direction to accommodate steep grades. Fifteen 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.In Budapest, the first prototypes of the Ikarus 180 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.
File:Crown-Ikarus bus of Tri-Met, Portland.jpg|thumb|Crown-Ikarus 286 for TriMet
In the mid-1960s, AC Transit in California pioneered the American use of a modern articulated bus, operating the experimental commuter coach "XMC 77" 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 14 March 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 and an observation lounge, complete with a card table to seat a quartet. The long coach stood high and was powered by a Cummins engine with an output of. 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 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/MAN joint venture responsible for assembling MAN SG 220 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, Italy, Germany, Canada, Hungary, Poland, Romania. The first modern British "bendy buses" 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 disadvantages
Advantages
The main benefits of an articulated bus over the double-decker bus are rapid simultaneous boarding and disembarkation through more and larger doors, increased stability arising from a lower center 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.Disadvantages
In some circumstances of urban operation, 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. The last disadvantage of an articulated bus is that it requires a specially trained driver in some cases.Articulated buses also struggle in snowy or icy conditions, because the rear axle delivers power; this causes the bus to “jackknife” or bend in the middle when attempting to go up a hill or through a snowdrift.
Use
An articulated bus is a long vehicle and usually requires a specially trained driver, as maneuvering can be difficult. 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.Europe
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.Malta
From 3 July 2011 to 28 August 2013, articulated Mercedes Citaro buses purchased from London were 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.United Kingdom
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 were lower than the cost and weight of the additional axle 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.Image:Citaro G Arriva London.jpg|thumb|Arriva London Mercedes-Benz Citaro O530G on route 73 at Oxford Circus in June 2006
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 turning against the concept.
Many of the articulated buses from London went on to serve with regional operators. Aside from limited use in regional cities, articulated buses may now be found at airports as park-and-ride shuttles.
A batch of 9 Mercedes-Benz Citaros currently run on First Aberdeen routes 1 and 2, and 5 others run with First York on York Park and ride services 2 and 3, but are being phased out by more modern Wright Streetdecks and Optare Metrodeckets
In 2020, twenty-one brand new Mercedes-Benz Citaros entered service at Stansted Airport; the Mercedes Benz Citaro is the only articulated bus available in the United Kingdom at present.
The last public Wright Eclipse Fusion bendy buses ran on 26 March 2023 on service 888 between Luton airport and Luton airport parkway station, the service being replaced by the Luton DART monorail service.