Tripper

An unscheduled trip• A one-way movement of a person or vehicle between two points for a specific purpose; sometimes called a one-way trip to distinguish it from a round trip. Also see boarding.
• The movement of a transit vehicle in one direction from the beginning of a route to the end of it; also known as a run.
More added to a route usually at peak hours to relieve crowding. Also known as Helper BusA rubber-tired transit vehicle designed for roadway operation to transport a large number of persons for public transportation service. In most cases, it operates with a self- contained source of motive power. More.