Articulated bus

An articulated bus is a high-capacity vehicle used for public transportation.

These vehicles are often called "slinky buses," "bendy buses," or "accordion buses." They consist of two or more rigid sections linked by a pivoting joint. This joint is known as an articulation. To keep the connection safe, the joint is enclosed by protective bellows. Inside the vehicle, a cover plate protects the floor. This design allows the bus to reach a longer legal length than standard rigid buses. Consequently, they can carry between 94 and 120 passengers.

The mechanism of an articulated bus allows for efficient movement and high capacity. Most common arrangements feature a forward section with two axles. The rear section typically has a single axle. The driving axle can be mounted on either the front or the rear section. Some models even include a steering arrangement on the rearmost axle. This axle turns slightly in opposition to the front steering axle. This feature helps the vehicle negotiate tighter turns in urban environments. It works similarly to how hook-and-ladder fire trucks operate in cities.

There are different types of articulated vehicles based on their size and structure. A standard articulated bus has one pivoting joint. A less common variant is the bi-articulated bus. This vehicle uses two trailer sections instead of just one. Bi-articulated buses are much longer and can carry around 200 people. Because of this massive size, they are used almost exclusively on high-frequency arterial routes. They are also a key part of bus rapid transit schemes. These systems may even include mechanical guidance or electric power.

The history of these vehicles began in the early 20th century. The first articulated bus appeared in Milan, Italy, in 1937. In 1938, the Twin Coach company built a bus for Baltimore. This specific model was articulated in the vertical direction. It was designed this way to accommodate steep road grades. By 1948, fifteen "Super Twin" buses were built. These could carry 120 total passengers. Later, in 1961, Budapest showed prototypes of the Ikarus 180. This bus was named for its 180-passenger capacity. It entered serial production in 1966 and was replaced by the Ikarus 280 in 1973.

In the United States, articulated buses saw significant use during specific eras. In the mid-1960s, AC Transit in California operated the "XMC 77."

This coach was nicknamed the "Freeway Train." It featured an observation lounge with a card table for passengers. During the late 1970s and early 1980s, many U.S. cities began importing buses from Europe. This was driven by rising operating costs. Transit systems wanted to transport more passengers using fewer drivers. In 1989, New Flyer Industries introduced the D60, a high-floor diesel model. They later developed the D60 LF, the first low-floor articulated bus in North America.

Articulated buses offer several engineering advantages over double-decker buses. They provide rapid boarding and disembarkation through more and larger doors. They also have a lower center of gravity, which increases stability. Because they have a smaller frontal area, they face less air resistance. This makes them more fuel-efficient than double-decker models. They can also pass under low bridges more easily. However, they do have disadvantages. In narrow streets, they may be involved in more accidents. In London, statistics showed they were involved in 20% of bus-related deaths.

This led to their replacement by double-deckers in 2011.

Operating these vehicles requires specific care and skill. Drivers often need special training to maneuver the long body. Reversing can be particularly difficult. The buses can also struggle in snowy or icy conditions. This is because the rear axle often delivers the power. If the bus tries to climb a hill in snow, it can "jackknife." This means the vehicle bends sharply at the middle joint.

Despite these challenges, they remain successful in many places. In Budapest, the BKV company has operated over 1,000 of them daily since the early 1970s.