A
bi-articulated bus or
double-articulated bus is a higher-capacity type of
articulated bus. It is an extension of a conventional or single-articulated bus, in that it has three passenger compartment sections instead of two. This also involves the addition of an extra
axle and a second articulation joint. Due to the extended length, bi-articulated buses tend to be used on high-frequency core routes or
bus rapid transit schemes rather than conventional bus routes.