Bi-articulated bus is an extension of an articulated bus in that it has three passenger compartment sections instead of two. This also involves the addition of an extra axle. 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.

Bus is a mode of transit service (also called motor bus) characterized by roadway vehicles powered by diesel, gasoline, battery, or alternative fuel engines contained within the vehicle. Vehicles operate on streets and roadways in fixed-route or other regular service. Types of bus service include local service, where vehicles may stop every block or two along a route several miles long. When limited to a small geographic area or to short-distance trips, local service is often called circulator, feeder, neighborhood, trolley, or shuttle service. Other types of bus service are express service, limited stop service, and bus rapid transit (BRT).

Bus rapid transit (BRT) is a term applied to a variety of public transportation systems that use buses to provide a service that is of a higher speed than an ordinary bus line. Often this is achieved by making improvements to existing infrastructure, vehicles and scheduling. The goal of these systems is to approach the service quality of rail transit while still enjoying the cost savings of bus transit.

Guided buses are buses steered for part or all of their route by external means, usually on a dedicated track. This track, which often parallels existing roads, excludes all other traffic, permitting the maintenance of reliable schedules on heavily used corridors even during rush hours. Guidance systems can be either physical, such as curbs, or remote, such as optical or radio guidance.

Trolleybus is a mode of transit service (also called trolley coach) using vehicles propelled by a motor drawing current from overhead wires via connecting poles called a trolley poles from a central power source not on board the vehicle.

Unlinked Passenger Trips (boardings) are the number of times passengers board public transportation vehicles. Passengers are counted each time they board vehicles no matter how many vehicles they use to travel from their origin to their destination and regardless of whether they pay a fare, use a pass or transfer, ride for free, or pay in some other way.