Automatic Train Operation, or ATO, is an ATC subsystem which performs on-board, non-vital functions normally performed by a train driver, including ensuring a smooth acceleration of the train to the running speed, speed regulation and smoothly stopping the train at the proper position at station platforms or in front of stopping signals. ATO subsystems are primarily located on-board and represent one of the principal components of a driverless system. Additionally, ATO subsystems report vehicle health status to the central control offices.