Automatic train operation


Automatic train operation is a method of operating trains automatically where the driver is not required or is required for supervision at most. Alternatively, ATO can be defined as a subsystem within the automatic train control, which performs any or all of functions like programmed stopping, speed adjusting, door operation, and similar otherwise assigned to the train operator.
File:Cab of T251 set 2037.jpg|thumb|Pictured is a train cab of a Kawasaki–CRRC Sifang T251 train serving the Mass Rapid Transit's Thomson–East Coast Line in Singapore. This line runs under ATO GoA 4, which is automatically controlled without any on-board staff.
The degree of automation is indicated by the Grade of Automation, 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 tracks. Fully automated trains for mainline railways are an area of research. The first driverless experiments in the history of train automation date back to 1920s.

Grades of automation

According to the International Association of Public Transport and the international standard IEC 62290-1, there are five Grades of Automation of trains. These levels correspond with the automotive SAE J3016 classification:
Grade of automationTrain operationDescription and examplesSAE levels
GoA0On-sightNo automation0
GoA1ManualA train driver controls starting and stopping, operation of doors and handling of emergencies or sudden diversions. Overseen signals due to human errors are safeguarded by train protection systems like ETCS L1.1
GoA2Semi-automatic Starting and stopping are automated using advanced train protection systems like ETCS L2 or 3, but a driver operates the doors, drives the train if needed and handles emergencies. Many ATO systems are GoA2. In this system, trains run automatically from station to station but a driver is in the cab, with responsibility for door closing, obstacle detection on the track in front of the train and handling of emergency situations. As in a GoA3 system, the GoA2 train cannot operate safely without the staff member on board. Examples include the London Underground's Victoria line and New York City Subway's 7 route.2
GoA3 Driverless Starting and stopping are automated, but a train attendant operates the doors and drives the train in case of emergencies. In this system, trains run automatically from station to station but a staff member is always in the train, with responsibility for handling of emergency situations. In a GoA3 system, the train cannot operate safely without the staff member on board. Examples include the Docklands Light Railway.3 and 4
GoA4 Unattended or Manless Starting, stopping and operation of doors are all fully automated without any on-train staff. It is recommended that stations have platform screen doors installed. In this system, trains are capable of operating automatically at all times, including door closing, obstacle detection and emergency situations. On-board staff may be provided for other purposes, e.g. customer service, but are not required for safe operation. Controls are often provided to drive the train manually in the event of a computer failure. CBTC is considered a basic enabler technology for GoA4. Examples include the Delhi Metro, Bangalore Metro, Vancouver Skytrain and the Singapore MRT.-

Additional types

Operation of ATO

Many modern systems are linked with automatic train protection and, in many cases, automatic train control 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. 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.

Advantages of GoA3+

In 2021, the Florida Department of Transportation funded a review by scientists from Florida State University, University of Talca and Hong Kong Polytechnic University, which showed the following advantages of autonomous trains:
  1. Eliminating human sources of errors
  2. Increasing capacity by stronger utilisation of existing rail tracks
  3. Reduction of operational costs. Paris Métro reduced its operational costs in case of GoA 4 by 30%.
  4. Increasing overall service reliability
  5. Improving fleet management and service flexibility
  6. Increasing energy efficiency

    Accidents and incidents involving ATO

While ATO has been proven to drastically reduce the chance of human errors in railway operation, there have been a few notable accidents involving ATO systems:
YearTerritoryIncident
1993JapanOn 5 October 1993, an automated Nankō Port Town Line train overran the line's southern terminus at Suminoekōen Station and collided with a buffer stop, injuring 217 people. The cause was believed to have been a malfunction in some of the relays in the line's ATO equipment that transmits the brake command signal, causing the brakes to not operate. Operations resumed on 19 November 1993 after redundancy equipment was installed and tested on the line.
2011ChinaOn 27 September 2011 at 14:51 hours local time, two trains on Shanghai Metro Line 10 collided between Yuyuan Garden station and Laoximen station, injuring 284–300 people. Initial investigations found that train operators violated regulations while operating the trains manually after a loss of power on the line caused its ATO and signalling systems to fail. No deaths were reported.
2015MexicoOn 4 May 2015, at around 18:00 hours local time during heavy rain with hail, two trains crashed at Oceanía station on Mexico City Metro Line 5 while both were heading toward Politécnico station. The first train, No. 4, was parked at the end of Oceanía station's platform after the driver reported that a plywood board was obstructing the tracks. The second train, No. 5, left Terminal Aérea station with the analogue PA-135 ATO system turned on despite the driver being asked to turn it off and to operate the train manually, as the protocol requests it when it rains because trains have to drive with reduced speed. Train No. 5 crashed into Train No. 4 at – double the average on arrival at the platforms – and left twelve people injured.
2017SingaporeJoo Koon rail accident – on 15 November 2017 at about 08:30 hours local time, one SMRT East-West Line C151A train rear-ended another C151A train at Joo Koon MRT station in Singapore, causing 38 injuries. At that time, the East-West Line was in the process of having its previous Westinghouse ATC fixed block signalling and associated ATO system replaced with the Thales SelTrac CBTC moving block signalling system. One of the trains involved had a safety protection feature removed when it went over a faulty signalling circuit as a fix for a known software bug, hence "bursting" the signalling bubble and leading to the collision.
2017IndiaBefore the prime minister was supposed to ride the train, a few days before the opening, a Delhi Metro train was undergoing ATO trials at the Kalindi Kunj Depot. As the train approached the buffer, it hit the buffers and derailed, hitting the front wall. The wall was eventually patched with bricks. However, it was eventually realized that the brakes were not applied by the train by default under the operation. This led to the trains being controlled by drivers until 2024, delaying the full UTO operations by seven years.
2019Hong KongA similar incident as the above occurred on the MTR Tsuen Wan Line in Hong Kong on 18 March 2019, when two MTR M-Train EMUs crashed in the crossover track section between Admiralty and Central while MTR was testing a new version of the SelTrac train control system intended to replace the line's existing SACEM signalling system. There were no passengers aboard either train, although the operators of both trains were injured. Before the crash site had been cleaned up, all Tsuen Wan line trains terminated at Admiralty instead of Central. The same vendor also provided a similar signalling system in Singapore, which resulted in the Joo Koon rail accident in 2017. In July 2019, the Electrical and Mechanical Services Department published an investigation report into the incident and concluded that a programming error in the SelTrac signalling system led the ATP system to malfunction, resulting in the collision.
2021Malaysia2021 Kelana Jaya LRT collision in Kuala Lumpur, in which 213 people were injured due to human error. The controller and backup controller computer have failed, a train driver was called in to drive the train to the depot. The train driver drives in the opposite direction of the track, leading to a collision with a train. ATP was not triggered due to the train's disappearance from the system as a result of both computers failing.
2022ChinaOn 22 January 2022, an elder passenger was caught between the traindoor and screendoor in Qi'an Road station of Line 15. On seeing the situation, the staff misoperated the traindoor controlling system, allowing the screen door to isolate without detecting, causing the train run a short while and fatally injuring the trapped passenger.
2023TaiwanOn 10 May 2023, a construction crane fell onto the tracks of Taichung MRT Green line south of Feng-le Park metro station. The driverless train was stationary when the crane fell onto the tracks and the train proceeded to drive and collide into the obstacle. Train attendants contacted the control center about the fallen crane obstructing the track. However, it would require 20 seconds to activate the emergency brakes remotely, which was insufficient to prevent the collision.
2025QuebecOn the early morning of November 22, 2025, a group of three people attempted to cross a highway and the tracks of the Réseau express métropolitain in Montreal, and were struck by a train near Du Quartier station. One person was killed immediately, and another died later in the hospital.