Concept
Automatic train operation (ATO) is a technology used to automate the operation of trains. The degree of automation is indicated by the Grade of Automation (GoA), up to GoA4 in which the train is automatically controlled without any staff on board. On most systems for lower grades of automation up to GoA2, there is a driver present to mitigate risks associated with failures or emergencies. Driverless automation is primarily used on automated guideway transit systems where it is easier to ensure the safety due to isolated track lines. Fully automated trains for mainline railways are an area of research. First driverless experiments in the history of train automation are dating back to 1920s. According to the International Association of Public Transport (UITP) and the international standard IEC 62290‐1, there are five Grades of Automation (GoA) of trains. These levels correspond with the automotive SAE J3016 classification: Many modern systems are linked with automatic train protection (ATP) and, in many cases, automatic train control (ATC) where normal signaling operations such as route setting and train regulation are carried out by the system. The ATC and ATP 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 coasting when moving and station dwell time in order to adhere to a defined timetable. Whereas ATP is the safety system that ensures a safe spacing between trains and provides sufficient warning as to when to stop. ATO is the "non-safety" part of train operation related to station stops and starts, and indicates the stopping position for the train once the ATP has confirmed that the line is clear. The train approaches the station under clear signals, so it can do a normal run-in. When it reaches the first beacon – originally a looped cable, now usually a fixed transponder – a station brake command is received by the train.
