The document discusses different types of railway signaling systems. It describes signals that provide facilities for efficient train movement, ensure safety between trains, and maximize track utility. The key types discussed include detonating signals for fog conditions, fixed visual signals, semaphore signals, warner signals, shunting signals, colored light signals, and reception/departure signals like home and starter signals that control train entry and exit at stations.

1. It consists of the systems, devices and
means by which trains are operated
efficiently and tracks are used to maximum
extent, maintaining the safety of the
passengers, the staff and the rolling stock.

2. To provide facilities for the efficient
movement of trains
To ensure safety between two or more
trains which cross or approach each
other’s path
To provide facilities for the maximum utility
of the track
To guide the trains movement during
maintenance and the repair of the track

3. Classification based on Operation
Characteristics
Classification based on Function
Classification based on Location
Special Signals

4. 1. Detonating Signals( Fog or Audible )
2. Hand Signals (Visual Indication)
3. Fixed Signals (Visual Indication)

5. 1. Stop or Semaphore type Signals
2. Warner Signals
3. Shunting Signals
4. Colored Light Signals (Disc or Ground)

6. Reception Signals
a) outer Signal b) Home Signal
Departure Signals
a) Starter b) Advanced Starter

7. 1. Repeater or Co-acting Signals
2. Routing Signals
3. Calling on Signals

8. Detonating signals otherwise known as
detonators or fog signals are appliances
which are fixed on the rails, and when an
Engine (or vehicle) passes over them, they
explode with a loud report so as to attract
the attention of the Driver.

9. Day Time: Wooden Flags or bare arms
Night Time: Lamps with movable glass
S.No Colours of Flags/Lights Meaning of Signals
1 Red Flag or Light Stop
2 Green flag or light Proceed
3 Yellow Light Proceed Cautiously

10.  Component Parts:
1.Movable Arm
L=1.2 to 1.7m
W= 23cn to25 cm
@7.5m above GL
2. Lenses
3. Signal Post

11. Warner Signals
A semaphore signal at the entrance to
station is combined with a Warner signal
V-Notch at free end
White band is also of V-shape
@1.8m to 2.1 m below the semaphore
signal
Painted yellow

14. For shunting operations @yards
Circular Disc with red band on a white
background .
Disc can revolve in vertical plane by pulling
the lever by hand
Two holes( Red, Green) for lamps

15. STOP Proceed

16. Replacement of semaphore signals
High intensity beam color light signals(day
or night)
Types:
1. Two Aspect( Green and Red)
2. Three Aspect( Green, Yellow and Red)
3. Four Aspect (Green, Yellow, Red and
Yellow)

17. STOP Proceed

19. STOP CAUTION PROCEED

20.  STOP CAUTION ATTENTION PROCEED

21. Signals controlling the reception of trains
into a station
Types:
Outer Signal
Home Signal

22. First stop signal at a Station
@0.54km in advance for BG
In STOP position -90 m distance prior to
Outer signal driver has to stop
In PROCEED position- move with normal
speed assuming the home signal is also
proceed position

23. OUTER SIGNAL
This is Warner signal for the driver which gives the indication of
the position ahead whether the platform is clear or not.
A certain distance is required to bring a moving train to halt.
This distance depends upon the speed of the train, its weight,
brake power of the locomotive etc.
Thus the first signal is provided at this distance beyond the
station limit, that is why it is know as outer signal

24. ASS
SS
HS
OS
OHS
SIGNALS ACCORDING TO LOCATION

25. In the inclined or proceed position it indicates that track and
platform is clear and proceed normally without any danger.
In horizontal or stop position it indicates that the driver must
bring his train to halt within 90 m before outer signal and than
proceed to the home signal with caution
OUTER SIGNAL
OS

26. HOME SIGNAL
After the outer signal towards station is a stop signal and exactly
placed at the station limit is called home or stop signal. Its main
function is to protect the stations. The permission to enter the
platform is given by the operation of this signal. The maximum
unprotected distance between the signal and the point, it is
intended to protect is specified as 180 m due to its location at the
door of station, it is called home signal.
HS
OHS

27. STARTER SIGNAL
This signal is provided at the forward end of platform and controls
the movement of the train as they leave the station. It gives
permission to the train to leave the platform for next station. No
train can leave the platform unless this signal is lowered, that is
why it is called starter signal. A separate signal is provided for
each line.
SS

28. ADVANCE STARTER SIGNAL
The limit of a station section lies between the home signal
and the advance starter signal. The signal which allows the train
to enter in block section is called advance starter signal. It is
always placed beyond the outer most set of the point connections.
ASS
SS
HS
OHS
station section

29. ROUTING SIGNAL
When many branch lines diverge in different directions from
the main line, it is very difficult to provide individual signal for each
line at the divergent point.
In such situations various signals for main line and branch
lines are fixed on the same vertical post. These signals are called
routing signal. Generally signal for main line is kept higher than
those for branch lines

30. REPEATING SIGNAL
When the view of the main signal is obstructed due to
some structures or on curves etc. some signals are used to repeat
the information of the main signal. Such signal are know as
repeating signal.

31. CALLING ON SIGNAL
These signal are similar to semaphore signal, but they
are smaller in size and are fixed on the same post below the
main signals. A calling on signal permits a train to proceed with
caution after the train has been brought to a halt by the main
signal. These are helpful when repair works are going on.