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 (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 (94–120), 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 18 m (59 ft) long, in contrast to standard rigid buses at 11 to 14 m (36 to 46 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 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 25 m (82 ft); as such, they are used almost exclusively on high-capacity, high-frequency arterial routes and on bus rapid transit services.

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 47 ft (14.33 m) 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 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 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 (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/MAN 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), Romania (DAC 117 UD). 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.^{[citation needed]}

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.