Due to their high passenger capacity, articulated buses are often used as part of bus rapid transit schemes, and can include mechanical guidance. 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 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. 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.