Automatic train operation

Definition
Automatic train operation (ATO) ensures partial or complete automatic train piloting and driverless functions. Most systems elect to maintain a driver (train operator) to mitigate risks associated with failures or emergencies.

Many modern systems are linked with Automatic Train Control (ATC) where normal signaller operations such as route setting and train regulation are carried out by the system. The ATO and ATC systems will work together to maintain a train within a defined tolerance of its timetable. The combined system will marginally adjust operating parameters such as the ratio of power to coast when moving and station dwell time, in order to bring a train back to the timetable slot defined for it.