The system that monitors and provide necessary commands to direct the operation of Trains in order to maintain the schedule in the required traffic patterns to minimise the effect of Train delays. Automatic Train Supervision System (ATS) is part of the Automatic Train Control (ATC) along with Automatic Train Protection System(ATP) .Refer Figure 1 for  the relation .Primary Function of an Automatic Train Supervision(ATS)  is to control and monitor the train operation .ATS is managing the train operation according to a time table or a specific headway or based on human (operator ) interaction on degraded mode of operation. A modern day ATS includes Automatic Train Regulation (ATR) and a Schedule Compiler.

Figure :1 Block Diagram of Automatic Train Control

ATS provide interface for the operator to supervise and manage trains. It provide real time status of the operating positions of the trains. ATS control launching of trains from storage facility to the commercially operating line and return the trains from operating lines to storage facility. It can also send manual and automatic commands to initiate and terminate train operations with override automatic command functionality. Modern day ATS system has some of the following functionality.

1. Operator can create and modify timetables.
2. Operator can monitor and control real time trains
3. Automatically send route call requests according to train operation requirements
4. Automatically send traffic locking calls based on train operation requirements
5. Automatically regulate train movements based on regulation needs.
6. Allow restore services and re-establish train operating patterns due to service delays and breakdowns
7. Tracking Train Positions in all signalled area.
8. Manage events and alarms from signalling system, trains and other signalling subsystems.
9. Supply real time train information to Public addressing system.
10. Generate performance reports for train service availability and train service quality factor.
11. Allow automatic and manual taking over of control centres, if have multiple control centres for redundancy purpose.
12. Capable of remotely control to open and close train doors and Platform Screen Door, if present
13. Can build centralized functionality and localized functionality.
14. Can build Train Description Facility for tracking and maintain a record of each train.

Functionality of a Modern Automatic Train Supervision System

1. Automatic Train Regulation (ATR)

 

Modern Day Train Automatic Train Supervision can regulate the train based on various train regulation strategies under automatic mode .It can dynamically regulate trains to maintain headway and time table .Automatic Train regulation allow operator to configure the level of service deviation and raise an alarm to the operator if the service deviation exceeds the set level.ATR functionality within ATS  can incorporate some of basic train regulation strategies.

1.1 Timetable Adherence

ATR feature of the ATS monitor real time train services to ensure they are on schedule. It recover services making use of corrective actions to maintain time table .Corrective actions can be  taken by adjusting station dwell times ,run times ( within the maximum speed of the track ) , coasting and adjustment of headway

1.2 Headway

ATR monitor the train services to ensure constant headway is maintained. Best suitable headway is selected based on number of trains allocated by operator (without exceeding the maximum number of trains possible within designed headway, usually 88 seconds or more ) .ATR can even alert the operator if he /she allocate more trains or headway if he/she exceed the limit .

2. Automatic Route Setting (ARS) facility

ATS  is capable of automatically make route calls based on train location ,time table and route strategies .ATS will not send a route call repeatedly to the interlocking if the route is not available .Rather it check route is already set by other request ,route is blocked or the requested route can cause a dead lock around terminal or turn around areas .Unlike  any other Entry-Exit ,or one control switch control system ATS can  store any route request and retry only when the route become available. In case the controller block a route and next controller try to set the route, ATS can alert the operator with the reason. ATS can automatically identify conflicting routes and when two trains approach a station can give priority to the train set which is scheduled to use the station first. ATS can allow override of automatic route setting for a manual route setting when needed. ATS ensures it will not set a route for an arriving train at a junction or a station platform which restrict a departing train to leave the platform

3. Manual Route Control facility

ATS can allow to perform manual route setting which can override the auto route setting. On modern day ATS you can find blocking and unblocking of signals and points for easy maintenance purpose with controlled reversal to avoid human error.

4. Station Dwell Time adjustments

As required operator can adjust station dwell time which can override the dwell time proposed by the timetable or ATR without affecting the T minimum Dwell time.

5. Platform Hold

ATS can allow the operator to prevent trains from station and hold. ATS can allow auto hold as well based on known scenarios. As an example, if at a time two trains cannot be at same place in one tunnel ventilation system, ATS apply hold functionality to halt one train at a station ,not allowing two trains comes to same section at same time. Similarly, when there is a fire in some tunnel section ATS can apply hold for trains in adjacent station.

6. Train Hold

ATS can allow the  operator to hold  and release a Train  at a station with status display on the workstation

7. Skip Stop

ATS can allow operator at an operating terminal to make a train skip a station or more as desired. When a hold command is applied before skip command, hold command take precedence over skip command as hold command could be  more related to fire and other safety related issues .

8. Train Control

ATS allow Train controller to manually control the train by sending remote wake up and sleep command. Command are normally issued automatic based on schedule or manually by an operator from a control terminal. ATS can also send command to  reset train borne ATC equipment. Operator can also send emergency brake release command. This will be ensured when ATC confirm its safe to release. Operator can have a remote command to open and close a train door when the track side equipment confirm its safe. In case there is a Platform Screen Door present in the system , command is   simultaneously issued to Platform Screen Door controller to open /close concurrently with the train door.ATS can also send a creep mode command to a train in automatic mode but suffers a ATO failure.

9. Temporary Speed Restriction (TSR)

An operator from his control terminal can apply and remove temporary speed restriction with immediate effect for any direction of travel in entire signalled area .It can also apply for a  track circuit section .TSR can vary from 0Km/Hr to the maximum design speed of the system.

10. Mode Inhibition

ATS can allow the operator to inhibit the mode of operation such as Automatic Mode(Grade of Automation 3/4)  ,Manual Mode(Grade of Automation 0 or 1)  ,Semi Auto Mode(Grade of Automation3)   for a train or entire fleet along the signalled area .

11. Time Table

ATS allow the operator to modify the running time table as per demand with in allowed headway and maximum trains possible in the line for that headway .Operator can create ,modify or delete a time table ,service ,trip or suspend a time table .In case by mistake operator suspend a time table ,ATS can allow through a command to resume from the current time. Controller workstation allow to load new time table ,modify origin ,destination ,dwell time ,arrival /departure time ,inter station run time ,coast level with recording of the controllers action on parameter change with time stamp. Operator can download the time table and send for printing.

12. Energy Optimisation

Based on traction power supply limitation ATS can optimise energy consumption by avoiding waking up trains at same time from same power zone to minimise rise in current.

13. Alarm and Events

ATS can alert the operator on any faults as needed by the operator through alarm ,warning based on the severeness  of criticality .Pre-emptive warning of any subsystem can also be alerted .Various railways use different background /text colour code for severity level .Severity level are configurable based on needs .ATS can also log and record events with time stamp and link with maintenance facility

14. Automatic /Manual Take Over

Depends on railway requirement there could be Main Control Centre ,Back up Control Centre ,Station Control Centre ,Depot Control Centre etc .In case of failure of Main Control Centre ATS server or Loss of communication between Station and Main Control Centre ,Station ATS can take over control to avoid traffic disruption .An operator at Main Control Centre  can manually  request take over control from another operator  at Station Control Centre

15. Automatic /Manual Hand Over Over

Similarly Handover can be done between control centre and Operator.

16. Modern Day Automatic Train Supervision

Refer Figure 2 for Modern Automatic Train Supervision System block diagram .Interconnection to other subsystem is out of scope for this article which will be covered in Architecture of a CBTC

 

Figure 2 Typical Automatic Train Supervision Interface

17. Summary

Automatic Train Supervision System paved way for a highly capable automatic  “vital “ control centre from conventional “Non Vital “Entry-Exit Control Panel or a One Control Switch Graphical User Interface Control Terminal .In a modern train control system ,especially Automatic Train Control system used in Communication Based Train Control System ,ATS has a significant role .