The document discusses signalling systems used in metro rail systems. It explains that signalling systems use trackside signals, train detection systems and communication to safely manage train movements and spacing. It describes how Continuous Automatic Train Control (CATC) systems using Communication Based Train Control (CBTC) help achieve high safety, reliability and capacity in metro operations. CBTC integrates Automatic Train Protection (ATP), Automatic Train Operation (ATO) and Automatic Train Supervision (ATS) using radio communication between trains and tracks. This allows trains to run safely at close headways while optimizing speeds. The document also discusses automatic fare collection (AFC) systems and their benefits for passengers and operators, as well as the role of the Operation Control Centre (

1. Metro system and
engineering
SIGNALLING SYSTEMS
SHUBHAM SHARMA
Department of civil engineering
BGIET, SANGRUR

2. Signalling systems in metro
 Signalling systems in metro are an integral part of the overall metro infrastructure. They are responsible for
controlling and managing the movement of trains, ensuring safe and efficient operations. Signalling systems use a
combination of trackside signals, train detection systems, and communication systems to provide information to the
train operators and ensure proper spacing and sequencing of trains.
 These systems help in maintaining safe distances between trains, preventing collisions, and optimizing train
movements to maximize capacity and minimize delays. Signalling systems play a critical role in ensuring the safety
and reliability of metro operations. Metro carries large number of passengers at a very close headway requiring a very
high level of safety enforcement and reliability. At the same time heavy investment in infrastructure and rolling stock
necessitates optimization of its capacity to provide the best services to the public.
 These requirements of the metro are planned to be achieved by adopting ‘CATC’ (Continuous Automatic Train Control
System) based on “CBTC” (Communication based Train Control System) which includes ATP (Automatic Train
Protection), ATO (Automatic Train Operation) and ATS (Automatic Train Supervision) sub-systems using radio
communication between Track side and Train.

3.  This will:
 Provide high level of safety with trains running at close headway ensuring continuous safe train separation and for
bidirectional working.
 Eliminate accidents due to driver passing Signal at Danger by continuous speed monitoring and automatic application
of brake in case of disregard of signal / warning by the driver. Provides safety and enforces speed limit on section
having permanent and temporary speed restrictions.
 Improve capacity with safer and smoother operations. Driver will have continuous display of Target Speed / Distance to
Go status in his cab enabling him to optimize the speed potential of the track section. It provides signal / speed status
in the cab even in bad weather.
 Increased productivity of rolling stock by increasing line capacity and train speeds, and enabling train to arrive at its
destination sooner. Hence more trips will be possible with the same number of rolling stock. Improve maintenance of
Signalling and telecommunication equipment's by monitoring system status of trackside and train born equipment's
and enabling preventive maintenance.

4.  How does signalling system work in metro system
 The signalling system in metros uses a combination of signals, track circuits, and train
detection devices to ensure safe and efficient train operations. The signalling system
communicates information to the train operators about the status of the track ahead, such
as whether it is clear or occupied by another train. This allows the operators to adjust their
speed accordingly and maintain a safe distance between trains. The signals, typically
displayed as coloured lights or symbols, provide visual indications to the train operators,
indicating whether they can proceed, slow down, or stop. The track circuits detect the
presence of a train by using electrical currents and provide continuous feedback to the
signalling system. This information is then used to control the movement of trains and
prevent collisions. The signalling system is designed to prioritize safety and ensure smooth
operations within the metro network.

5. Cab signalling
 is a device by which signal aspects are displayed inside the cab of Loco Pilot (Driver) indicating the speed at which he
should drive his train.
 Besides, Cab Signalling is answer for adequate safety and maintaining efficient operation of rail services even under
adverse visibility conditions as Loco Pilot is not dependent on visibility of track side signals.
 Train movements on running tracks shall normally be governed by the Automatic Train Protection system which displays
to the Train Operator in the operating console
(a) actual speed of the train.
(b) the maximum permitted speed at each point of travel.
(c) the distance the train is currently authorized to travel (where provided).
(d) system alarms;

6.  Locomotive cab interior and cab signal
(e) Messages
 if the target speed indication and the target distance indication, where provided, are greater than zero, the
indication is referred to as "PROCEED" indication.
 if either of these indications is "0", the indication is referred to as "STOP" indication;.
 (The Train Operator is authorised to drive his Train up to the indicated speed as far as authority has been
given for such purpose.

7. Fixed Signals
 on main lines, fixed signals are colour light signals, either showing two 15 aspects or three aspects.
 (ii) Two aspects fixed signals, where provided, shall be capable of showing a "Red" or a "White or violet"
aspect.
 a "Red" aspect indicates that a train must be brought to STOP short of the signal.
 a "White or violet" aspect indicates that the route is set and locked but may not be fully clear up to the
next fixed signal and a train operating under cab signals may proceed under the authority of the cab
signals but a train operating on the sole authority of line side signals must stop and seek instructions
from the Traffic Controller.
 (iii) Three aspect signals, where provided, shall be capable of showing a "Red", "White or Violet" or
"Green" aspect.
 a "Red" aspect indicates that a train must be brought to STOP short of the signal.

8.  a "White or Violet aspect indicates that the route is set and locked but may not be fully clear up to the
next fixed signal and a train operating under cab signals may proceed under the authority of the cab
signals but a train operating on the sole authority of line side signals must stop and seek instructions
from the Traffic Controller.
 a "Green" aspect indicates that the route is cleared to the next fixed signal and the train may proceed as
far as the next fixed signal.
 (iv) When a fixed signal is not in use, the aspect shall be covered and the cover shall display two crossed
white bars on a black background, the bars being not less than thirty centimetre's long and ten
centimetre's wide.

9. Depot Signals
 in depots, fixed signals may be colour light or position light type. Colour light type using Red and Yellow aspects
should be used in the manner as specified below:
 a "Red" aspect indicates that a train must be brought to STOP short of the signal;
 a "Yellow" aspect indicates that the route is set, locked and clear and a train may proceed in "Restricted Manual"
mode as far as the line is clear and the Train Operator must keep a good look out for any obstruction.
 (ii) in position light type signalling
 two white lights displayed horizontally shall mean that a train must stop.
 two white lights displayed at an angle shall mean that a train may proceed in Restricted Manual mode as far as
the line is cleaned the Train Operator must keep a good lookout for an obstruction.
 (iii) the Depots and stabling lines shall be isolated from the running line through an approved means.

10. Automatic fare collection
 Automatic fare collection (AFC) is a convenient and efficient system used in metro systems to automate
the fare payment process. It eliminates the need for manual ticketing and allows passengers to enter and
exit the metro stations seamlessly.
 In AFC systems, passengers use fare cards or smartcards to pay for their metro rides. These cards can be
loaded with a certain amount of credit or linked to a bank account. When passengers enter the metro
station, they tap their cards on the fare gates or validators to deduct the appropriate fare from their
balance. Similarly, when they exit the station, they tap their cards again to calculate the fare for the
distance travelled.
 AFC systems offer several benefits, such as faster entry and exit times, reduced queues at ticket counters,
and improved overall efficiency. They also provide valuable data for metro operators, allowing them to
analyse passenger patterns, manage fare structures, and plan for future expansions.
 Different AFC technologies are used in metro systems, including contactless smartcards, mobile payment
apps, and even biometric systems. These technologies continue to evolve, providing more convenience
and security for metro passengers.

12. Using AFC in metro systems offers several benefits for both passengers and
metro operators:
1. Convenience: AFC eliminates the need for
manual ticketing, reducing the time and effort
required for passengers to purchase tickets.
Passengers can simply tap their fare cards or use
mobile payment apps for seamless entry and
exit.
2. Speed and Efficiency: With AFC, the entry and
exit process becomes faster, leading to reduced
queues and congestion at metro stations. This
improves the overall flow of passengers and
ensures smoother operations.
3. Cost Savings: AFC systems can help reduce
operational costs by minimizing the need for
manual ticketing infrastructure, such as ticket
booths and staff. It also reduces the risk of
revenue leakage and fare evasion.
4. Data Collection and Analysis: AFC systems
provide valuable data on passenger patterns,
such as peak travel times, popular routes, and
fare revenue. Metro operators can analyse this
data to optimize service planning, adjust fare
structures, and make informed decisions for
future expansions.
5. Improved Security: AFC systems enhance
security by reducing the use of cash and
minimizing the risk of theft. Passengers can
securely load their fare cards or link them to their
bank accounts, ensuring a safe and convenient
payment method.
 Overall, AFC systems enhance the passenger
experience, streamline operations, and provide
valuable insights for metro operators.

13. Operation Control Centre
 The Operation Control Centre (OCC) is a vital component of metro systems. It serves as the nerve
centre where all operations and monitoring take place. The OCC is responsible for ensuring the safe
and efficient operation of the entire metro network.
 In simply, The OCC is like the brain of a metro system. It's where operators keep an eye on
everything that's happening. They monitor train movements, coordinate emergency response, and
make sure all the systems are running smoothly. The OCC also provides real-time information to
passengers and helps keep them safe and informed. It's an essential part of keeping the metro
running efficiently and ensuring a great experience for everyone.
 The OCC is equipped with advanced technology, including computer systems, monitoring screens,
and communication tools, to effectively manage and control the metro system. It plays a crucial
role in maintaining the smooth operation of the network and ensuring a safe and reliable
transportation experience for passengers.

14. Within the OCC, trained personnel oversee various functions,
including:
1. Train Control: Monitoring and controlling train movements, ensuring adherence to schedules, and
managing any disruptions or emergencies.
2. Power Supply and Distribution: Monitoring the power supply and distribution systems to ensure
uninterrupted operation of trains and station facilities.
3. Communication and Signalling: Managing communication systems between the OCC, train
operators, and station staff. This includes monitoring signals, controlling switches, and ensuring
effective communication during emergencies.
4. Passenger Information: Providing real-time information to passengers regarding train schedules,
delays, and any service disruptions. This can be done through public address systems, digital displays,
or mobile applications.
5. Incident Management: Coordinating responses to incidents, accidents, or emergencies that may
occur within the metro system. This involves working closely with emergency services and
implementing appropriate protocols to ensure passenger safety.

16. SCADA
 Supervisory Control and Data Acquisition systems are used as control systems in metro
operations. They play a crucial role in monitoring and controlling various aspects of the
metro infrastructure to ensure safe and efficient operations.
 SCADA systems allow operators to remotely control and manage different systems within
the metro, such as train operations, power supply, signalling, ventilation, and security.
Operators can monitor train movements, track occupancy, and schedule adherence. They
can also control train functions like doors, lighting, and ventilation from a centralized
control canter.
 By providing real-time data and control capabilities, SCADA systems empower operators
to make informed decisions, optimize operations, and respond quickly to any issues or
emergencies that may arise in the metro system.

17.  SCADA ensures the safety of metro operations through various mechanisms. It continuously
monitors critical parameters such as train movements, track occupancy, and power supply to
detect any abnormalities or potential risks. If any safety thresholds are breached or anomalies
are detected, SCADA triggers alarms and alerts operators in real-time, allowing them to take
immediate action to mitigate risks and ensure the safety of passengers and personnel.
 Additionally, SCADA integrates with other safety systems such as signalling, interlocking, and
emergency response protocols. It provides operators with a comprehensive view of the metro
system, enabling them to coordinate and respond effectively to emergencies, manage train
movements, and ensure safe operations.
 By providing real-time data, remote control capabilities, and proactive monitoring, SCADA
enhances the overall safety of metro operations and helps prevent accidents or incidents.

18. Platform screen doors
 Platform screen doors, also known as PSDs, are an important feature in metro systems. They
are installed along the platform edge and act as a physical barrier between the platform and
the tracks.
 PSDs provide several benefits in metro operations. First and foremost, they enhance
passenger safety by preventing accidental falls or unauthorized access to the tracks. They
create a controlled environment, reducing the risk of accidents and ensuring the safety of
passengers waiting for trains. Additionally, PSDs help improve the overall efficiency of the
metro system. They facilitate faster boarding and alighting of passengers by aligning with the
train doors. This reduces dwell time at stations, allowing trains to maintain their schedules
and ensuring smooth operations.
 PSDs also contribute to the comfort of passengers by reducing noise levels and minimizing
the impact of weather conditions, such as wind gusts or extreme temperatures, on the
platform. Overall, platform screen doors are an important feature in metro systems,
prioritizing passenger safety, improving efficiency, and enhancing the overall travel
experience.

19. Working of platform screen doors
 Platform screen doors (PSDs) work by creating a physical barrier between the platform and
the tracks in a metro system. They are typically made of transparent or translucent materials,
allowing passengers to see the tracks and trains.
 PSDs are synchronized with the train doors, ensuring that they open and close
simultaneously. When a train arrives at the platform, the doors of both the train and the
PSDs align, creating a continuous barrier along the platform edge. The PSDs have sensors
that detect the position of the train doors. Once the train doors are fully open, the PSDs
open as well, allowing passengers to board or alight the train. When it's time for the train to
depart, the PSDs close, ensuring that no one can access the tracks.
 In addition to the synchronized operation with the train doors, PSDs also have safety
features. They are equipped with sensors that detect any obstructions or anomalies, such as
objects or people caught between the doors. If an obstruction is detected, the PSDs will stop
closing or retract to prevent any accidents. Overall, platform screen doors enhance passenger
safety, streamline boarding and alighting processes, and contribute to the overall efficiency
of metro systems.

21. Types of PSD
 There are several types of platform screen doors (PSDs) used in metro systems. Some common types include:
1. Full-Height PSDs: These are the most common type of PSDs and extend from the platform floor to the ceiling,
providing a complete barrier between the platform and the tracks.
2. Half-Height PSDs: As the name suggests, these PSDs only cover the lower half of the platform, leaving the upper
half open. They are often used in stations with lower platform heights or where there is a need for a more open feel.
3. Sliding PSDs: Sliding PSDs are doors that slide horizontally to open and close. They are typically installed in stations
with limited space or where vertical movement of the doors is not feasible.
4. Retractable PSDs: These PSDs retract vertically into the ceiling when not in use, creating an open platform. They are
commonly used in stations where the platform width is limited or in stations with varying train sizes.
5. Platform Edge Doors: Platform edge doors are a variation of PSDs that are installed directly on the platform edge.
They operate independently of the train doors and provide an added layer of safety.

22. Thankyou