Automatic train operation


Automatic train operation is an operational safety enhancement device used to help automate the operation of trains. The degree of automation is indicated by the Grade of Automation, up to GoA level 4. ATO is primarily used on automated guideway transit and rapid transit systems where it is easier to ensure the safety of humans. On most systems, there is a driver present to mitigate risks associated with failures or emergencies.
Many modern systems are linked with automatic train control and, in many cases, automatic train protection where normal signaller operations such as route setting and train regulation are carried out by the system. The ATO and ATC/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 coast when moving and station dwell time in order to adhere to a defined timetable.

Types of train automation

According to the International Association of Public Transport, there are five Grades of Automation of trains:
Grade of
automation		Train operationDescription
GoA 0On-sightSimilar to a tram running in street traffic
GoA 1ManualA train driver controls starting and stopping, operation of doors and handling of emergencies or sudden diversions.
GoA 2Semi-automatic Starting and stopping are automated, but a driver operates the doors, drives the train if needed and handles emergencies. Many ATO systems are GoA 2.
GoA 3Driverless Starting and stopping are automated, but a train attendant operates the doors and drives the train in case of emergencies.
GoA 4Unattended train operation Starting and stopping, operation of doors and handling of emergencies are all fully automated without any on-train staff.

Operation of ATO

Whereas ATP is the safety system which 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. The on-board computer calculates the braking curve to enable it to stop at the correct point, and as the train runs in towards the platform, the curve is updated a number of times to ensure accuracy.
When the train has stopped, it verifies that its brakes are applied and checks that it has stopped within the door-enabling loops. These loops verify the position of the train relative to the platform and which side the doors should open. Once all this is complete, the ATO will open the doors. After a set time, predetermined or varied by the control centre as required, the ATO will close the doors and automatically restart the train if the door closed proving circuit is complete. Some systems have platform screen doors as well. ATO will also provide a signal for these to open once it has completed the on-board checking procedure. Although described here as an ATO function, door enabling at stations is often incorporated as part of the ATP equipment because it is regarded as a "vital" system and requires the same safety validation processes as ATP.
Once door operation is completed, ATO will accelerate the train to its cruising speed, allow it to coast to the next station brake command beacon and then brake into the next station, assuming no intervention by the ATP system.

Notable examples

Urban passenger railways

ATO was introduced on the London Underground's Northern line in 2013 and will be introduced on the Circle, District, Hammersmith & City, and Metropolitan lines by 2022. ATO will be used on parts of Crossrail once the route opens. Trains on the central London section of Thameslink were the first to use ATO on the UK mainline railway network with ETCS Level 2.
The U-Bahn in Vienna will be equipped with ATO in 2023 on the new U5 line.
All lines being built for the new Sydney Metro will feature driverless operation without any staff in attendance.
Since 2012, the Toronto subway has been undergoing signal upgrades in order to use ATO and ATC over the next decade. Work has been completed on the Yonge–University line, supplanting pointing and calling. Other lines, however, rely on the practice to ensure trains are correctly positioned at stations. The underground portion of Line 5 Eglinton will be equipped with ATC and ATO in 2022. The underground portion will use a GoA2 system while the Eglinton Maintenance and Storage Facility will use a GoA4 system and travel driverless around the yard. The Ontario Line is proposed have a GoA4 driverless system and will open in 2027.
ATO is in everyday operation on Czech Railways lines with :de:Allgemeiner Vertrag für die Verwendung von Güterwagen|AVV since 1991, and in test operation with ETCS since 2008.
Delhi Metro officials have stated that driverless trains with advanced features will run on the Botanical Garden – Kalkaji corridor, with trial runs planned for the last week of July 2016 and the trains being operated on the route from August 2016 onwards. Initially, drivers will be deputed to operate the trains but will be gradually withdrawn, said a metro official.