Wiktionary
n. A bus fitted with a joint to increase its manoeuvrability.
Wikipedia
An articulated bus (either a motor bus or trolleybus) is an articulated vehicle used in public transportation. It is usually a single-deck design, and comprises two rigid sections linked by a pivoting joint (articulation) enclosed by protective folding bellows on the in- and outside of the vehicle (usually of gray or black colour) and a cover plate on the inside of the vehicle. This arrangement allows a longer legal overall length than single-decker rigid-bodied buses, and hence a higher passenger capacity, while still allowing the bus to maneuver adequately on the roads of its service route.
Around the English-speaking world, articulated buses have acquired several different synonyms that allude to their articulated design, such as bendy buses, bending buses, tandem buses, stretch buses, double buses, banana buses, slinky buses, wiggle buses, caterpillar buses, accordion buses or vestibule buses . Due to their high passenger capacity, articulated buses are often used as part of bus rapid transit schemes, and can include mechanical guidance.
Used almost exclusively on public transport bus services, articulated buses are approximately in length; standard rigid-construction buses are usually . 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 bus models have a steering arrangement on the rearmost axle which turns slightly in opposition to the front steering axle, allowing the vehicle to negotiate turns in a crab-like fashion, 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 about .