CAMTECH/S/2001/Basic Concepts/SCR-4 1

COURSE CONTENTS

1. Knowledge and necessity of Signals – Fail Safe Feature of Signaling

System

2. Definition of Signaling terms as given G & SR

3. Concept of LQ; UQ Signaling; Colour Light Signals

4. Overlaps; Braking distances: Sighting Distance

5. Location of Signals

6. Subsidiary Signals

7. Markers, Boards, Signs, etc.

8. Isolation, Slip Siding & Catch Siding

9. Simultaneous Reception and dispatch of trains

10. Classification of stations – Minimum signaling equipments required at

each class of station

11. Standards of Inter Locking – Minimum Signaling equipments required

at each standard of inter locking.

12. Level crossing gates

13. Inter cabin control

14. System of train working (Block Working)

15. Control of outlying sidings through Block Instruments

16. Station Working rules

17. Signaling Plan CAMTECH/S/2001/Basic Concepts/SCR-4 2

Lesson Plan Long Course

No. of Hours Teaching Aids Topic Theory Practicals Theory Practicals Knowledge and necessity of 1 signals – fail safe feature of signaling system. Definition of signaling terms as 3 given in G & SR Concept of LQ, UQ signaling color 2 OHP Wallchart light signals Overlaps, braking distance, 2 OHP sighting distance Location of signals 3 2 OHP Wallchart Model Room Subsidiary signals 2 2 OHP Wallchart Model Room Markers, Boards, Signs, etc 3 2 OHP Wallchart Model Room Isolation, slip siding, catch siding 2 2 OHP Model Room Simultaneous reception and 2 2 Model Room dispatch of trains Classification of station – minimum 4 2 Block board Model Room signaling equipments required at OHP each class of station Standards of signaling – minimum 4 2 OHP Wallchart Model Room signaling equipments required each standard of signaling Level crossing gates 2 2 OHP Model Room Inter cabin control 2 2 OHP Model Room System of train working (block 4 2 OHP Wallchart Model Room working) Block instruments, methods of 6 3 OHP Wallchart Model Room block working, control of outlying sidings Station working rules 2 2 OHP Open Line Signaling plan 2 1 OHP Wallchart Open Line CAMTECH/S/2001/Basic Concepts/SCR-4 3

Lesson Plan Short Course Minutes Teaching Aids Topic Theory Practicals Theory Practicals Knowledge and necessity of 20 signals – fail safe feature of signaling system. Definition of signaling terms as 30 OHP given in G & SR Concept of LQ, UQ signaling color 30 OHP Wallchart light signals Overlaps, braking distance, 20 OHP sighting distance Location of signals 20 15 OHP Wallchart Model Room Subsidiary signals 20 20 OHP Wallchart Model Room Markers, Boards, Signs, etc 30 OHP Wallchart Isolation, slip siding, catch siding 25 30 OHP Model Room Simultaneous reception and 20 OHP dispatch of trains Classification of station – minimum 30 30 OHP Wallchart Model Room signaling equipments required at each class of station Standards of signaling – minimum 60 30 OHP Wallchart Model Room signaling equipments required each standard of signaling Level crossing gates 30 OHP Wallchart Inter cabin control 20 OHP Wallchart System of train working (block 60 60 OHP Wallchart Model Room working) Block instruments, methods of 30 30 OHP Model Room block working, control of outlying sidings Station working rules 30 OHP Signaling plan 30 OHP CAMTECH/S/2001/Basic Concepts/SCR-4 4

NECESSITY OF SIGNALS

Signaling Concepts :

Railway vehicles move on steel rail track and engines, wagons and coaches are provided with flanged steel wheels. The rolling of steel wheels on the steel rail has the least friction and therefore, it is the most efficient means of locomotion.

Unlike road vehicles, railways have no capacity to steer away. They have to follow a fixed path, as guided by these rails. They are required to follow one another.

Precedence and crossings can be arranged only at station. Drivers of a locomotive has only control over the speed of the train, he can start and stop.

This communication to the driver to proceed or to stop is through signals.

What are Signals :

Signal is medium to convey a particular predetermined meaning in non-verbal form. Signals of non-verbal form are also used in road transport, navy and air traffic control etc.

Fixed Signals :

A signal of fixed location indicating the condition affecting movement of train.

It includes Semaphore arm, or a disc or fixed light used by day or night. CAMTECH/S/2001/Basic Concepts/SCR-4 5

Semaphore is a Greek word. SEMA stands for Sign, PHERO means bear.

Semaphore signal is rectangular or fish tailed at the end. Fixed on a vertical post, kept horizontal. Easily distinguishable from longer distances.

There are three methods of display : i) Vertical - Parallel to post. ii) Midway Position - below horizontal. iii) Midway Position - above horizontal.

Various Forms of Signals :

Signals

Visual Audible

Detonators Voice Whistle

Movable Fixed Flare

Semaphore CLS Position Light

LQ UQ 2 Aspect Multiple Aspect CAMTECH/S/2001/Basic Concepts/SCR-4 6

DEFINITIONS (As per GR 1.02)

ACT :Means the Indian Railways Act, 1989.

ADEQUATE DISTANCE :Means the distance sufficient to ensure

Safety.

APPROACH LIGHTING :Means an arrangement in which the

lighting of signals is controlled automatically

by the approach of a train.

APPROVED SPECIAL INSTRUCTIONS :

Means special instructions approved of or

prescribed by the Commissioner of Railway

Safety.

AUTHORISED OFFICER :Means the person who is duly empowered

by general or special order of the Railway.

Administration, either by name or by virtue

of his office, to ensure instructions or to do

any other thing.

AUTHORITY TO PROCEED :Means the authority given to the driver of a

train, under the system of working, to enter

the block section with his train. CAMTECH/S/2001/Basic Concepts/SCR-4 7

AXLE COUNTER :Means an electrical device which, when

provided at two given points on the track

proves by counting axles in and counting

axles out. Whether the section of the track

between the said two points is clear or

occupied.

BLOCK BACK :Means to dispatch a message from a block

station intimating to the block station

immediately in rear on a double line or to

the next block station on either side on a

single line, that the block section is

obstructed or is to be obstructed.

BLOCK FORWARD :Means to dispatch a message from a block

Station on a double line intimating to the

block station immediately in advance the

fact that the block section in advance is

obstructed or is to be obstructed.

BLOCK SECTION :Means that portion of the running line

between two block stations on to which no

running train may enter until line clear has

been received from the block station at the

other end of the block station. CAMTECH/S/2001/Basic Concepts/SCR-4 8

COMMISSIONER OF RAILWAY SAFETY :

Means a Commissioner of Railway safety

appointed to exercise any functions under

the act and includes the chief

Commissioner of Railway safety.

CONNECTIONS : When used with reference to a running

line, means the points and crossings, or

other appliances used to connect such line

with other lines to cross it.

DIRECTION OF TRAFFIC : a). On a double line, the direction for

which the line is signaled.

b). On a single line, the direction for the

time being established, under the system of

working to allow trains to move in that

direction.

FACING AND TRAILING POINTS :

Points are facing or trailing in accordance

with the direction of a train or vehicles

moves over them. Points are said to be

facing points when by their operation a train CAMTECH/S/2001/Basic Concepts/SCR-4 9

approaching them can be directly diverted

from the line upon which it is running.

FIXED SIGNAL : Means a signal of fixed location indicating

a condition affecting the movement of a

train and includes a Semaphore arm or disc

or fixed light for use by day and fixed light

for use by night.

FOULING MARK : Means the marks at which the

infringement of fixed standard dimensions

occurs, where two lines cross or join one

another.

INTER LOCKING : Means an arrangement of signals, points

and other appliances, operated from a

panel or lever frame, so inter connected by

Mechanical locking or Electrical locking or

both that their operation must take place in

proper sequence to ensure safety.

INTERMEDIATE BLOCK POST :

Means a class “C” station on a double line,

remotely controlled from the block station in

rear. CAMTECH/S/2001/Basic Concepts/SCR-4 10

INTERMEDIATE BLOCK SIGNALLING :

Means an arrangement of signalling on

double line in which a long block section is

split in two portions each constituting a

separate block section by providing an

Intermediate Block post.

ISOLATION : Means an arrangement, secured by the

settings of points or other approved means

to protect the line so isolated from the

danger of obstruction from other connected

line or lines.

LAST STOP SIGNAL : Means the fixed stop signal of a station

controlling the entry of a train into the next

block station.

LEVEL CROSSING : Means the intersection of road with railway

track at the same level.

LINE CLEAR : Means the permission given from a block

station to a block station in rear for a train to

leave the latter and approach the former, or CAMTECH/S/2001/Basic Concepts/SCR-4 11

the permission obtained by a block station

from a block station in advance for a train to

leave the former and proceed towards the

latter.

MAIN LINE : Means the line ordinarily used for running

trains through and between stations.

MULTIPLE ASPECT SIGNALLING :

Means a signalling arrangement in which

signal displays at any one time any one of

the three or more aspects and in which the

aspect of every signal is pre-warned by the

aspect of the previous signal or signals.

OBSTRUCTION : And its cognate expressions include a

train, vehicle or obstacle on or fouling a line,

or any condition, which is dangerous to

trains.

POINT AND TRAP INDICATORS :

Are not signals, but are appliances fitted to

and working with points to indicate by day

or by night the position in which the points

are set. CAMTECH/S/2001/Basic Concepts/SCR-4 12

RUNNING LINE : Means the line governed by one or more

signals and includes connections, if any,

used by a train when entering or leaving a

station or when passing through a station or

between lines.

RUNNING TRAIN : Means a train, which has started under an

authority to proceed, and has not completed

its journey.

SHUNTING : Means the movement of a vehicle or

vehicles with or without an engine or any

other self-propelled vehicle for the purpose

of attaching detaching or transfer or for any

other purpose.

SPECIAL INSTRUCTIONS : Means instructions issued from time to

time by the authorised officer in respect to

particular case, or special circumstances.

STATIONS : Means any place on a line of Railway at

which traffic is dealt with, or at which an

authority to proceed is given under the

system of working. CAMTECH/S/2001/Basic Concepts/SCR-4 13

STATION LIMITS : Means the portion of a railway, which is

under the control of a station master and is

situated between the outermost signals of a

station or as may be specified by special

instructions.

STATION MASTER : Means the person on duty who is for the

time being responsible for the working of

the traffic without station limits, and includes

any person who is for the time being in

independent charge of the working of any

signals and responsible for the working of

trains under the system of working in force.

STATION SECTION : Means the section of station limits.

1) At a class ‘B’ station provided with two

aspect signals, which is included :

a) On a double Line, between Home

signal and the Last stop signal of the

station in either direction ; OR

b) On a single line

(i) Between the shunting limit

board or advanced starter’s (if

any) or CAMTECH/S/2001/Basic Concepts/SCR-4 14

(ii) Between the home signal if

there are no shunting limit

boards or advanced starters,

or

(iii) Between the outer most facing

points, if there are no Home

signals or Shunting limit

Boards or Advanced starters.

2). At a class “B” station provided with

manually operated multiple aspect or

modified lower quadrant signals, which is

included ;

a) On a double line

(i) Between the Outer most

facing points and the last stop

signal of the station in either

direction,

OR

(ii) Between the Block section

limit board, where provided,

and the last stop signal of the

station in either direction

b) On a Single Line

(i) Between the Shunting limit CAMTECH/S/2001/Basic Concepts/SCR-4 15

Boards or Advanced Starters

(if any)

OR

(ii) Between the Outermost facing

points if there are no shunting

limit board or Advanced

starters.

SUBSIDIARY RULE :Means a special instruction which is

subservient to the general rule to which it

relates and shall not be at variance with any

General Rule.

SYSTEM OF WORKING :Means the system adopted for the time

being for the working of trains on any

portion of a railway.

TRACK CIRCUIT :Means an electrical circuit provided to

detect the presence of a vehicle on a

portion of a track, the rails of the track

forming part of the circuit. CAMTECH/S/2001/Basic Concepts/SCR-4 16

CONCEPT OF LQ, UQ SIGNALING

Semaphore Signals can be displayed in any 4 quadrants. In India we follow left-hand rule. Hence we use L H Quadrant.

In lower quadrant only two aspects 0o and 45o is possible. 3rd position

coincides with post. Hence not useful.

o o o In upper quadrant 3 aspects 0 , 45 and 90 is possible. CAMTECH/S/2001/Basic Concepts/SCR-4 17

Two Aspect Lower Quadrant Signals :

Stop Signals : It is a Semaphore arm – Square ended, painted red with

white bar parallel to the square end rear side – white painted with black bar to

distinguish approach of signal direction.

ON Aspect - arm at 0o ON Aspect - arm at 45o

Night - Red light Night - Green light

Aspect- Stop Aspect- Proceed .

R G

Indication : Stop Dead. Indication : Proceed. ON Position OFF Position

Need for Warner Signal :

A stop signal when taken OFF indicated Proceed i.e., he has to proceed till he

finds next signal. That means the driver has to keep a continuous watch to

locate the aspect of the next signal in advance. This is continuous strain on

the part of the driver. It affects the speed of trains and punctuality in case of

poor visibility. It is quite possible the driver may encounter ON aspect

suddenly and unable to stop short of signal. He may overshoot the signal at

ON. This is most dangerous situation, and it may cause accident. Hence, there is a need for a Warner signal. Warner signal has a different design of arm, to pre-warn the stop signal ahead. CAMTECH/S/2001/Basic Concepts/SCR-4 18

Warner Signal:

Semaphore arm: Fish tailed end painted red with white bar. In rear painted

white with black bar. Warner signal can be located on an independent post or below a stop signal.

ON Independent post:

Fixed Fixed Green Green

1.5 to 2

Green Red

ON Aspect - Arm at 0o OFF Aspect - arm at 45o Aspect - Proceed with caution Aspect - Proceed Indication - Proceed with caution & Indication - Proceed be prepared to stop at next Stop signal. Night aspect - Red light below fixed Night aspect- Greenlight Green light below fixed Green light.

OFF aspect indicates all stop Signals ahead are clear, the Train can run through. CAMTECH/S/2001/Basic Concepts/SCR-4 19

NOTE :

i. A Warner signal must not be capable of being taken OFF for any line

other than that over which the highest speed is permitted. ii. Until all the relevant signals have assumed OFF aspect that means,

Permission to enter in to next block section is also taken. iii. Even if any one of the Stop signals ahead is ON the Warner should not

display OFF aspect.

Warner below a Stop Signal :

Under certain circumstances, a Semaphore Warner is required to be place on the same post of a stop signal. Then the fixed green light is dispensed with.

There are three indication to the Drivers :

Aspect : Stop Proceed with Caution Proceed

Indication : Stop Dead Proceed with Caution and Proceed. Block

be prepared to stop at the section ahead is

next stop signal clear.

Pre-warning to the driver of an approaching train can be given only when a

Warner signal is placed on a post by itself. In the case of Warner Signal placed below a stop signal, no pre-warning is available for the Stop signal. In both the cases, Warner signal taken OFF indicates “Run Through” condition –

All signals ahead taken OFF. Pre-warning of all stop signals is only possible with MAUQ signaling. CAMTECH/S/2001/Basic Concepts/SCR-4 20

Multiple Aspect Upper Quadrant Signaling :

Stop Signal : Semaphore arm square ended arm painted red with white bar in front. Painted white with black bar in rear.

ON Position OFF Position

Red

Y G

Aspect : Stop Caution Proceed Indication : Stop Dead Proceed and be Proceed Prepared to stop at next stop signal. CAMTECH/S/2001/Basic Concepts/SCR-4 21

The second yellow light is visible only in 450 position. It is not to be visible in any other position (00 and 900 position). A mechanical arrangement is made to blank out the signal (yellow aspect) in any position other than 450 aspect.

ON Position OFF Position

Y

Y G

Caution Attention Proceed

Permissive Signals and Absolute signals :

Warner signals in Two aspect and Distant signal in Multiple aspect are not stop signals. They permit approaching driver to pass these signals in ON position. Hence they are called Permissive signals.

The Stop signals in 2 aspect and Multiple aspect can not be passed at ON unless and until they are specially authorised by the SM or the signal is changed to OFF position. Hence they are called Absolute Signals. CAMTECH/S/2001/Basic Concepts/SCR-4 22

Distant Signal :

The further most signal at a station and first signal approached by an incoming train is the distant signal in multiple aspect upper quadrant signaling.

Arm is fish tailed painted yellow with black bar parallel to fish tail. Rear painted white with black bar.

Night - ON position - Yellow light

45o Position - Two Yellow lights, one below the other.

90o Position - Green light. CAMTECH/S/2001/Basic Concepts/SCR-4 23

Colour Light Signals

Due to the following advantages Colour Light Signals are used instead of

Semaphore Signals.

• In Colour Light Signals both day and night aspects are the same –

avoids confusion to drives

• Signals have longer range of visibility – especially during night.

• No Mechanical Moving parts – Easy to maintain.

• Not limited due to range of operation, as in mechanical signals

• Improved reliability of signals

• Improves punctuality.

M A C L S – 3 Aspect – Stop Signal

ON Position OFF Position

Aspect : Stop Caution Proceed

G

Y

R

Indication : Stop Dead Proceed and be Proceed Prepared to stop at Next stop signal CAMTECH/S/2001/Basic Concepts/SCR-4 24

ON Position OFF Position

G

Y Y R

Aspect : Stop Caution Attention Proceed Indication : Stop Dead Proceed and be Proceed and be Proceed Prepared to stop at prepared to pass next stop signal. next stop signal at Restricted speed CAMTECH/S/2001/Basic Concepts/SCR-4 25

M A C L S – 4 Aspect Stop Signal

M A C L S – 3 Aspect – Distant Signal

ON Position OFF Position

Y

Y

Y Y

P P P

Caution Attention Proceed

C L S – 2 Aspect – Stop Signal

ON Position OFF Position

Stop Proceed CAMTECH/S/2001/Basic Concepts/SCR-4 26

Warner – ON a post by itself

ON Position OFF Position

Fixed Fixed Green Green

G

R

P P

Aspect – Proceed with caution Proceed Indication – Proceed with caution and be Proceed Prepared to stop at the next stop signal

Warner below a Stop Signal

GG R

ON Position OFF Position

Aspect : Stop Proceed with caution Proceed Indication – Stop Proceed with caution and Proceed Block section ahead be prepared to stop is clear at the next stop signal CAMTECH/S/2001/Basic Concepts/SCR-4 27

DESIGNATION OF SIGNALS

Signals are necessary to provide the required space interval between the trains. Signals are necessary to control the entry of trains in to the block sections, into the stations and with in the stations for different purposes.

Signals are designated describing the function of the signals.

APPROACH SIGNALS : Signals provided for receiving a train is known as

Approach Signals

HOME SIGNALS : Stop signal at the approach of a station. It gives

entry to the housing point i.e., station.

Home Platform

BRACKETED SOME SIGNAL : Where there is more than one line, each line is provided with Home Signal. All such Home signals are bracketed on a common post or a gantry. CAMTECH/S/2001/Basic Concepts/SCR-4 28

ROUTING SIGNAL : In cases more than one receiving line may be available for different groups. Distance between home and station stop may be longer.

Routing

May have different places for the trains to stop. These are called Routing signals.

OUTER SIGNAL : Where the reception of train is controlled by more than one signal, then the first stop signal (F S S) is called the Outer Signal and the second stop signal, Home signal.

Outer Home

An outer signal can also be placed above a Warner signal on the same post.

Home Warner Y Outer CAMTECH/S/2001/Basic Concepts/SCR-4 29

PERMISSIVE SIGNAL : Warner/ Distant There may be additional one or more permissive signals to pre-warn the presence of a stop signal. in two aspect signals, we have Warner signals on independent posts.

Warne Outer Home ∨

In multiple aspect signaling, we have distant signals.

Distant ∨ Home

In case more than one distant signal is used, the second one as approached by driver is called Inner Distant (Provided in some multiple aspect signaling sections).

Distant Inner Home Distant

DISPATCH SIGNALS

Signals are also provided to control departure of trains. The signals authorize the drivers to start the train and also enter into next block section. If only one departure signal is provided, they are called Starter signals, they also control the entry in to next block section.

Starter (LSS) CAMTECH/S/2001/Basic Concepts/SCR-4 30

If more than one stop signal controls the movement of trains to start and enter into next block sections, then the last stop signal is called ADVANCED STARTER signal which controls the entry in to next block section other Starter signals are provided near the fouling marks.

Starter Advanced Starter

Starter

In some stations, more than one-dispatch signals are provided and this signal between starter and advanced starter is called Intermediate starter signal.

LSS

LSS

Starters Intermediate Starters

OVERLAPS

Overlaps are referred to as adequate distance.

Block Over Lap (B O L) : It is the extra length of track in advance of the first

stop signal of a station, which must be kept clear, before Line clear can be

given to the station in rear.

Signal Over Lap (S O L) : The length of track in advance of Stop Signal,

which must be kept clear before the signal next in rear could be taken OFF. CAMTECH/S/2001/Basic Concepts/SCR-4 31

Two aspects B O L : 400 Mts., S O L : 180 Mts.,

Multi aspects B O L : 180 Mts., S O L : 120 Mts.,

For Automatic Block Signaling – BOL/SOL – 120 Mts.

By increasing the number of aspects, Overlaps can be reduced without sacrificing Safety because signal aspects can be repeated by signals in rear in a rational manner.

BRAKING DISTANCE :

The distance traveled by a train after its brakes are applied is known as

Braking distance.

There are two methods of Application of Brakes :

¾ Normal Service application

¾ Emergent application including setting in reverse.

Braking distance depends on :

(i) Speed

(ii) Brake power available

(iii) Gradient

(iv) Rollability of wheels

(v) State of rails, curvelence of track

(vi) Wind velocity, weather condition (dry or wet)

(vii) Type of train

(viii) Load of train CAMTECH/S/2001/Basic Concepts/SCR-4 32

After all tests, it is now decided that for a full load passenger train on level of gradient at 65 kmph, the braking distance is 1 km approximately.

SIGHTING DISTANCE :

The distance over which the most restrictive aspect of a signal is visible from

the driving compartment of an approaching train under normal condition of

visibility.

REACTION DISTANCE :

It is the distance traveled at the permissible speed during the time taken by

the driver to react to the aspect of signals.

Minimum Sighting Distance = NBD + RD

Sighting distance is an uncertain factor – In two aspect signaling – signals are

not pre-warned.

In multiple aspect all signals are pre-warned by aspects of signals in advance.

PRESCRIBED SIGHTING DISTANCE :

TWO ASPECT :

Outer – 1200 Mts. Where section speed is 100 kmph and above

Warner : (on independent post) – 400 Mts. CAMTECH/S/2001/Basic Concepts/SCR-4 33

Home - 400 Mts.

Main Starter – 400 Mts.

All other Signals – 200 Mts.

MULTIPLE ASPECT :

Distant – 400 Mts.

Inner distant – 200 Mts.

All stop signals – 200 Mts.

Where not possible to have continuous visibility as above, speed of trains is to be suitably restricted. CAMTECH/S/2001/Basic Concepts/SCR-4 34

LOCATION OF SIGNALS

Signals are normally located on to the left side of the track. However, for

better visibility a signal may be located on the right side also.

Two Aspect Homes :

Should be located close to first set of facing points clear of lock bar. If it is

necessary to increase the distance between the Home and Facing points

beyond 180 Mts. Other arrangements should be made for holding the route.

Multi Aspect Homes :

Should be located at 300 Mts. Is (180 + 120 Mts.) from the first facing points.

Facility for shunting in face of approaching if provided, the home may be shifted outward. So that block overlap is available between the home and opposing advance starter or shunting limit board. On double line, Home may be located at 180 Mts. in rear of facing point or Block section limit board.

Starter Signals :

Should be located at the leaving end fouling marks or lines in the case of parallel lines at distance exceeding train length from the signal in rear. The distance between the homes and starting should not be less than 400 Mts. In the case of LQ signaling and 180 Mts. in case of Multi aspect Signaling. An alternative location is signal overlap in rear of fouling mark. This provides more operational advantages. CAMTECH/S/2001/Basic Concepts/SCR-4 35

Advanced Starter :

On single line at 180 Mts. from Outer most trailing point. The distance may be increased if required, provided the opposing outer in ‘B’ class station, the

home in MAUQ as the case may be can be located at a distance of at least

block overlap from the adv. Starter. On double line it should be placed at full

train length plus signal overlap in advance in Starter signals. But in the

present practice the advance starter signals are being located at 120 Mts.

from Outer most trailing points.

Outer :

On single line at 580 Mts., between Outer home (so that the BOL & SOL for

an opposing train being received at stations is available). Where there is an

advance starter or SLB; it should be ensured that block overlap of 400 Mts. is

available between it and opposing outer. On double line, a distance of 400

Mts. should be provided between it and corresponding home.

Warner / Distant :

These signals are located at normal braking distance plus reaction distance in

rear of the stop signals in advance of them. Where it is not possible to

provide normal braking distance at least emergency braking distance equal to

1 km to be provided.

Double Distant :

In accordance with GR 3.07(6) two distant signals (Distant signal and Inner

distant signal) have been provided in some multiple aspect signaling sections. CAMTECH/S/2001/Basic Concepts/SCR-4 36

The second distant signal is generally placed at a distance of 2 Kms from the first stop signal eliminating Warning Board.

The meanings of the aspects of these signals are as under :

Indication to Distant Inner Home Main line Adv Driver Signal Distant Signal Starter Starter

May stop at Double Yellow Red - - Home Yellow

May stop at Green Double Yellow Red - Main line starter Yellow

To Run through Green Green Green Green Green To stop at Loop Double Double Yellow Starter or Pass Yellow Yellow with route Via loop Indicator.

Subsidiary Signals :

Subsidiary signals are those signals, which control the movement of trains with in the station section.

Shunt Signals :

1) Authorize movement only at such a slow speed, so as to be able to stop

short of obstruction and Control shunting movements.

2) Shunt signals, when taken OFF, authorizes the driver to draw ahead even

though Stop signal above it is at ON.

Shunt signals can be a Disc type, Position light; Miniature arm type (under spl.

Instructions) CAMTECH/S/2001/Basic Concepts/SCR-4 37

Disc type : Circular disc painted white with red horizontal bar in the front and white with black bar in rear.

ON Position OFF Position

R LQ Red R Green

UQ R

Red Yellow

R

Aspect: Stop Aspect: Proceed slow Indication: Stop Dead. Indication: Proceed with caution for shunting CAMTECH/S/2001/Basic Concepts/SCR-4 38

Position light : Position light shunt signals are considered on Colour Light Signals. They are same both for two aspect of Multiple aspect; LQ or UQ day and night aspects are the same.

ON aspect OFF aspect Two lights Horizontal Two lights inclined

White White Light Light

Miniature Semaphore type : Arm Square ended. Painted with Red with white bar provision of this signal only under special instructions.

ON Position OFF Position

OFF ON G

R LQ

R Y UQ CAMTECH/S/2001/Basic Concepts/SCR-4 39

Calling ON Signal :

Always provided below a Stop signal. Generally for the approach of a train. It is taken OFF when the main stop signal has failed (unable to be taken OFF) should be taken OFF only after the train has come to stop. Callings on Signals are two types.

1) Miniature arm type : Arm Square ended painted white with Red bar in the front while with black bar in the rear

ON Position OFF Position UQ

R RED

R R

No-Light Y

ON Position OFF Position LQ

Red Red

No Light Yellow CAMTECH/S/2001/Basic Concepts/SCR-4 40

2) Colour Light Type : Colour light type are provided with C marker plate. Under approved special instructions, calling on Signal can be provided below a stop signal, except LSS.

ON Position OFF Position

NO LIGHT MINIATURE . YELLOW LIGHT

C C

Repeating Signals :

Repeating Signals are used. 1) When ever minimum visibility is not available for a fixed signal 2) To inform the driver about the condition of the main signal in advance.

They are provided with R marker and are required only for two aspect signals (In MA all signals are pre-warned). CAMTECH/S/2001/Basic Concepts/SCR-4 41

Types of repeating signals are :

Square ended Semaphore arm type : Painted yellow with black bar in the front painted white with black bar in rear.

ON Position OFF Position

RR

Banner type :

Disc painted whited back ground. A yellow rectangular arms with black boarders at the top and bottom. It rotates on a central pivot it takes 45o position in LQ, when main signal is taken OFF. It is not lit during nighttime.

ON Position OFF Position

Y Y

R R CAMTECH/S/2001/Basic Concepts/SCR-4 42

Colour Light Type :

It is generally provided in 2 aspect CLS.

ON Position OFF Position

Signal Signal with it with it repeats is R R repeats is at ‘on’ at ‘off’

Co-acting Signals : All the fixed signals must have a minimum visibility to

the driver and be continuously visible to the driver. When it is not possible to

have continuous visibility due to foot over bridges or tunnels or any other obstruction, co-acting signals are provided. Co-acting signals are duplicate signals fixed below running signals on the same post at such a height that either main signal or co-acting signal is visible. Main signal and co-acting signals are rigidly connected. They work together. CAMTECH/S/2001/Basic Concepts/SCR-4 43

Markers provided on the Signal post :

P marker for permissive signals P P letter in black on white disc fixed between the signal

C marker for calling ON signal C C letter in black on white disc

R marker for repeating signal R R letter in black on white disc

G marker for Gate stop signal G G letter in black on Yellow disc

IB marker for intermediate BLOCK IB IB letter in black on white disc Stop Signal

Repeating Signal in CLS territory R R white illuminated against black back ground

A marker on automatic stop signal A A letter in black on white disc CAMTECH/S/2001/Basic Concepts/SCR-4 44

A marker lit on Semi automatic A A lit on black back ground disc Signal When working as automatic mode. A extinguishes when working in manual mode

Indicators: Point indicators (target type) Points set straight Day Night

WHITE WHITE LIGHT TARGET

POINTS SET FOR TURNOUT

EDGE OF TARGET GREEN LIGHT TARGET TYPE NIGHT DAY TRAP INDICATORS OPEN OPEN CLOSE CLOSE

RED TARGET GREEN LIGHT RED TARGET EDGE OF TARGET

SIGNAL NOT GOODS RINGS R R IN USE ON SIGNALS . . TO READ GOODS LINE DOCK PLATFORM SIGNALS CAMTECH/S/2001/Basic Concepts/SCR-4 45

Indication Boards : Shunting Limit Board : Provided on single line. To distinguish limit up to

which shunting can be performed in the face of an approaching train. A black

across on yellow back ground. Temporary lit during night. Visible from both sides. Fixed on a post-painted white and black alternately.

Shunting Limit Board

Block Section Limit Board :

Provided on multiple aspect double line territory only. Provided where there

are no facing points or when the outer most facing points at the approaching end is a trailing point. A black cross on yellow back ground. Temporary lit

during night, visible from both sides. Fixed on a post painted white and black

alternately.

BLOCK SECTION LIMIT BOARD CAMTECH/S/2001/Basic Concepts/SCR-4 46

S Marker Provided at an intermediate siding taking OFF from main line. Provided in the facing direction. A circular board with black letter S on yellow back ground.

S S S

Warning Board : Provided in rear of first stop signal or gate stop signal at a minimum distance

of 1400 Mts. place left side of line to which it refers. To give an indication to

driver that he is to be on the look out for stop signals. Where double distant is

provided Warning Board is dispensed with CAMTECH/S/2001/Basic Concepts/SCR-4 47

Indication boards are also provided to give warning to the driver about change

in type of signaling or block working etc.

The board will have suitable legend like

“ENTERING TOKEN TERRITORY”

“ENTERING TOKENLESS TERRITORY”

“ENTERING AUTOMATIC BLOCK TERRITORY”

ISOLATION :

The term Isolation denotes the condition in which line for a particular movement is separated from all adjoining line connected to it in such a manner that the isolated lines cannot be fouled or interfered with by any

movement-taking place on the adjoining lines.

Rules regarding Isolation :

1) A line which train movements at speeds higher than 50 kmph are

permitted, the line should be isolated from all connected lines.

2) Passenger lines should be isolated from all connected lines and

sidings, what ever the speed may be.

3) Isolation of goods reception lines from sidings is considered

desirable

4) To maintain safety in thorough running, points and trap sidings

should not be inserted in the main or through lines. Exceptions to

this rule, may be adopted with the special sanction of CRS is

obtained are : CAMTECH/S/2001/Basic Concepts/SCR-4 48

i. Where other means cannot be adopted, to permit simultaneous

reception of trains on single line sections.

ii. To trap vehicles running away from a station

iii. To avoid trains entering from block section due to heavy falling

gradient.

Methods of Isolation : 1) Connecting to another line or a siding

Loop Siding

Main

2) Provision of short dead end sliding (Vehicles should not be stabled on this siding). Loop Siding

Main

3) Provision of traps, derailing switches (inexpensive, popular dependable)

Loop TRAP

MAIN

4) Long dead end siding with trap (Vehicles can be stabled on this siding)

Loop Trap SDG

Main

5) Provision of sand humps. Sand Hump Loop

Main CAMTECH/S/2001/Basic Concepts/SCR-4 49

Slip Sidings and Catch sidings :

For all gauges the maximum gradient permitted are 1 : 400, where as 1 : 1200

is usually allowed with in the station yard. No station yard should be steeper

than 1 : 260 except due to geographic conditions, where such a gradient can

not be avoided with in the station yard, CRS condonation has to be obtained

and special arrangements like “Slip Sliding” has to be provided.

Slip Sdg

Block Section

1 : 250 Slip Sdg

Slip Sliding due to gradient steeper than 1 : 100 falling away from the station in the close neighborhood.

SLIP Sliding

Block section

L 1:90

If the gradient is steeper than 1 : 80 falling towards the station. Arrangement of Catch siding is to be provided. It is to trap vehicles coming uncontrolled from the block section and trying to enter into the station. CAMTECH/S/2001/Basic Concepts/SCR-4 50

CATCH Sdg

Block section

1: 75 1:75 L

Catch siding due to falling gradient while approaching the station if steeper than 1 : 80.

Slip Sliding and Catch Siding points must be interlocked with the block instruments and such sidings should not be used for shunting or stabling purposes.

Simultaneous Reception and Dispatch of Trains :

Taking OFF at the same time, of all signals pertaining to the reception of two

or more trains approaching a station at the same time is called simultaneous reception.

Advantages :

™ In single line section, track/section capacity will increase, if at all the

stations, such facilities are made available.

™ In double line, one train can be started from one line, while another train

can be signaled to be received on another line. CAMTECH/S/2001/Basic Concepts/SCR-4 51

Methods of Providing Simultaneous Reception Facility :

1) In double line sand humps may be provided replacing traps.

loop

DN main

UP main

loop

2) Provision of sand humps on single section

Maximum flexibility but expensive CAMTECH/S/2001/Basic Concepts/SCR-4 52

3) Provision of two sand humps

Economical but platform facility may not be available for passenger train in one direction

4) Extending loops to have signal overlaps on reception lines beyond starter

SOL SOL

SOL

SOL

5) By providing calling on signal (after trains come to a stop at FSS). CAMTECH/S/2001/Basic Concepts/SCR-4 53

CLASSIFICATION OF STATION AND MINIMUM EQUIPMENT REQUIRED AT EACH CLASS OF STATION

Irrespective of the system of working in force the stations are classified as

block station and non-block stations.

Station : Means any place on a line of railway at which traffic is dealt with, or

at which an authority to proceed is given to the driver of the train under the

system of working.

Block stations : Block stations are those at which driver must obtain an authority to proceed under the system of working to enter the block section with his train.

Non-Block station : These are outlets opened for commercial purpose and

no block working is carried here.

To cope up with different working conditions stations are categorized in to

various classes.

Class A Station : Where line clear may not be given for a train unless the

line on which it is intended to receive the train is clear for at least 400 Mts.,

beyond the Home signal or up to the starter.

Class B Station : Where line clear may be given for a train before the line has been cleared for the reception of the train with in the station section. CAMTECH/S/2001/Basic Concepts/SCR-4 54

Class C Station : At which no train is booked to stop. This includes IBS, line clear may not be given for a train, unless the whole of the last proceeding train has passed complete at least 400 Mts. beyond the Home signal and is continuing its journey.

Class D Station : Situated between two consecutive block stations and do not form the boundary of any block section.

Minimum signaling equipment required for each class of station

Class of Station Minimum Equipment Additional Equipment Two Aspect Warner, Home, Starter Under approved A Class Special instruction, Outer, Warner behind outer. B Class Outer, Home Starter on double (on Single Line) line, Warner if Outer, Home, Starter speed exceeds 50 (On Double Line) kmph. Adv. Starter or SLB where shunting in the face an approaching train is required. C Class Warner, Home D Class Non Block Station CAMTECH/S/2001/Basic Concepts/SCR-4 55

Multiple Aspect B Class Distant, Home, Starter Advance starter or SLB where shunting in the face of an approaching train is required. Block section limit board where no points or outer most point is trailing point at the approach end. C Class Distant, Home

On Double Line : Starter signals are included in the minimum equipment for

A and B class as entry in to next block section is controlled by signal

indication above. Warners are provided for high-speed operation to provide the means for adequate interlocking, starter signals are not used in C class

working because trains normally do not stop at such stations. In all these

types of stations, before permission to approach is given, the line must be

clear up to the first stop signal and the adequate distance beyond it.

Standards of Signaling :

Interlocking : Interlocking can be defined as an arrangement between

points, signal appliances either electrically or mechanically or both to secure the following objectives : CAMTECH/S/2001/Basic Concepts/SCR-4 56

1) It shall not be possible to take OFF signals for a route unless all the points

are correctly set and the facing points are locked for the route, including

overlap.

2) Once the signals are cleared, it shall not be possible to alter the points on

the route unless the signals are put back to ON.

3) Even though the signals are put back to ON, it shall not be possible to alter

the points unless the intended movement over such points is completed.

4) It shall not be possible to operate signals leading to conflicting

movements.

5) The points and signals can be operated only in a sequence to ensure

safety.

6) Where signals are connected through any devices, the signal shall not

obey until the conditions for working such devices are fulfilled.

Standards of Interlocking : In the interests of safety, train speeds should depend on the signal and telecommunication equipment provided. Four standards of interlocking are prescribed.

Zero : Uninterlocked. Speed up to 15 kmph.

One : Standard I for speeds up to 50 kmph.

Two : Standard II for speeds up to 75 kmph.

Three : Standard III for unrestricted speed. CAMTECH/S/2001/Basic Concepts/SCR-4 57

Minimum Signaling Equipments required at each standard of signaling

Minimum Equipments ZERO STD1 STD2 STD3 Points: 1. How gauge is maintained A gauge tie Plate where – Steel sleepers- Are not provided

2. How Operated May - be worked – locally - From a frame where points and signal levers are grouped. 3. How Locked Bolt and A key lock of A plunger type A Plunge type of Colter approved type of FPL locking FPL worked from locking each each switch the frame. switch independently, independently which may be hand operated 4. How Switches are No Spl. Interlocked With signal. Lock – bar/track prevented from being Arrangemen circuit or such unlocked under a train t other means 5. Switch detection Not required A means for – Detecting each Switch ntly should be provided independently 6. Lock detection Not required Not required Yes, if plunger Desirable is hand operated or is of the economical type Isolation : 1. Isolation of main line Not required Not required Required Required 2. Isolation of Passenger Required Required Required Required lines from goods lines and sidings. Grouping of Levers: Not required Signal lever - Should be Signal and point grouped & - key provided to levers should be enable SM - lock up frame grouped Interlocking NIL Indirect by Indirect Direct between means of key interlocking point & signal lock Warner should be levers and where should extended to all there are different interlock trailing points locations SMs trailing points. direct locking supervisory control Direct locking between signal should be between signal levers. provided. levers. Signals Two aspect CAMTECH/S/2001/Basic Concepts/SCR-4 58

A Class Not usually Adopted Warner Home Starter B Class Outer, Outer, B/Home Outer; B/Home Outer; B/Home Common Warner to be and Starter Home interlocked with block instrument if starter is not provided MAUQ / MACLS A Class Not usually - Adopted MAUQ / MACLS B Class Distant Distant Home Distant Home Distant Home home starter MAUQ / MACLS C Class Not usually - Adopted

Thus it can be summarized that signaling arrangements provided at a stations

should be based on.

1) Compatibility of the signaling equipments with speeds obtaining on the

section.

2) Ensuring optimum utilization of line capacity.

3) Efficient and smooth train working with in the station limits.

4) Economical use of man power.

5) Promoting flexibility, safety and reliability in yard operation. CAMTECH/S/2001/Basic Concepts/SCR-4 59

Even though the existing signaling equipments cater to the above

consideration, the arrangements can not be satisfactorily interfaced. With the

technology updating programs to user in better and faster train services.

Provision of signaling equipments at station should be spelt out in real terms

with capacity to absorb the fore seeable changes in the near future with as

little alterations, in the signaling arrangements as possible.

Thus in this context a new format has been brought out under M, Chapter VII.

Part I of the revised signal engineering manual 1988.

Level Crossing Gates :

Level Crossing means the intersection of road with railway track at the same level. Any form of movable barrier capable of being closed across the road traffic at the level crossing is known as level crossing gate.

Level Crossing gates are three types :

Single leaf, Double leaf; Lifting barrier. Single and double leaf gates open

away from the track. They are locked in succession by E type locks.

The lifting barriers when operated for road traffic, it is vertically lifted up and in

closed condition it is horizontal across the road traffic.

Boom gates are provided in single or double units on each side and are

mechanically or power operated.

Classification : Level crossing gates shall be classified as special class, A

class B Class C class and D class. The classification shall be settled mutually CAMTECH/S/2001/Basic Concepts/SCR-4 60 by engineering department in consultation with the local government authorities after conducting the railroad traffic census.

Special Class A Class B Class} For Road Vehicles C Class D Class For Cattle Crossings.

Location : As far as possible level crossing shall not be located near stations and marshalling yards. If inevitable they shall be located beyond shunting limits in the station yard.

Control and Protection : The working of the level crossing gates with in the stop signals is under the control of the SM and the working of those out side the stop signals is under the control of permanent way department.

TWO ASPECT

1.4 K.M B : O 400 m >

G >

1.4 K.M MAUQ 1 KM B : O 180 m >

G

> CAMTECH/S/2001/Basic Concepts/SCR-4 61

Protection of level crossing gates inside the station limits :

In the case of level crossing gates inside the station limits of block station worked under absolute block system the stop signals on either side of the level crossings are utilized to function also as gate signals by providing interlocking between them and the level crossing gates. But if the stop signals are not available new signals are to be installed for protecting important level crossings.

Gate cum 1.4 K.M Distant Less Than B.D Gate Distant 1 KM G

180 M

120 M G 180 M

180 M 1 KM

ADV.STR cum GATE DISTANT

Inter Cabin Control

Principles of Slotting: The control of signals by more than one source, other than the operating source is called slotting. The source, which releases the slot, is called slotting agency. The source, which actually operates the signal, is called Operating agency. CAMTECH/S/2001/Basic Concepts/SCR-4 62

Purpose of slotting : 1) To ensure that the points located on the line controlled by the signal

including the overlap are set correctly and facing points locked and the line

is clear, before the signal is taken OFF.

2) These conditions are maintained until the train movement is completed.

In other words no other conflicting or fouling movement is allowed to take

place and the points are not altered until the train movement is completed.

Because a slotted signal can be replaced to its most restrictive aspect by

any one of the slotting agencies.

Extract of SEM.

Para No. 158 : Except where qualified cabin men are employed, the SM must be provided with interlocked mechanical or electrical control over

Warner, home and LSS.

Para No. 159 : Control of Starters / Advanced starters on single line.

At single line stations, where token instruments are used, the advance starter

or where there is no advance starter, the starters must be controlled by the

block instruments of the corresponding section.

Para No. 160 : Control of Starter / Advanced starters on Double Line. At

Double Line stations where block instruments are in use the advanced starter

or where there is no advanced starter, the starter must be controlled by the L

C indication of the block instrument of the corresponding section. CAMTECH/S/2001/Basic Concepts/SCR-4 63

System of Train Working – Block Working

Control Over movement of trains :

Basically control over the movements of trains can be achieved by two methods.

™ Time interval method

™ Space interval method

Time Interval Method :

Movement of trains can be controlled and adequate interval between two trains in the same direction can be maintained by dispatching the following train with sufficient time interval after the departure of the preceding one.

In this system, safety is not fully ensured. Since the driver has to ensure that the earlier train is moving forward and proceedings without stopping. This is a definite strain on the drivers he has to keep a continuous watch over the earlier train to avoid collision.

Further this is not practicable in respect of Railways due to

- Different types of trains, viz., Goods, Passengers, Express

trains.

- Different types of Powers / Locomotives.

- Different speeds of trains.

- Different haulage capacity of trains.

- Different braking capacity of locomotives.

- Different terrain.

- Different loads of trains.

- Different stoppages. CAMTECH/S/2001/Basic Concepts/SCR-4 64

Space Interval System is one in which, in to a given length of track only one train at a time is permitted to enter. Second on subsequent train is permitted to enter the same length of track, from one of the two sides, only after the first train has cleared the said track.

¾ This ensures safety

¾ Length of the track is divided into sections called Block Section.

¾ At the end of each Block section, there is a Block Section.

¾ Entry into each Block section is controlled through electrical block

instruments and is protected by signals.

¾ Information is conveyed to the driver to proceed or stop by signals.

¾ The object of the Space Interval system is to preserve a definite interval of

space between trains running on the same line.

Systems of Block Working : To maintain space interval, for safe running of trains, in Indian Railways, six systems of train working are adopted. They are : 1. Absolutely Block System 2. Automatic Block System Normally used 3. Following train System 4. Pilot Guard System 5. Train staff & Ticket System. Used only with permission of Rly. Board 6. One train only System

Absolute Block System :

Essential requirements (as per para 8.01 of GR). a) No train shall be allowed to leave a block station unless line clear has

been received from the block station in advance. CAMTECH/S/2001/Basic Concepts/SCR-4 65 b) On double line such line clear shall not be given unless the line is clear not

only up to the first stop signal at the block station at which such line clear

is given but also for an adequate distance beyond it. c) On single line such line clear shall; not be given unless the line is clear of

such trains running in the same direction not only up to the first stop signal

at the block station at which such line clear is given but also for an

adequate distance beyond it and is clear off trains running in the direction

towards the block station to which such line clear is given.

This adequate distance is the block overlap which shall not be less than

400 meters in LQ / two aspect signaling / two aspect CLS

180 meters in UQ / multiple aspect signaling or modified LQ signaling.

Any reduction to this block overlap requires specific sanction of CRS (under approved special instructions).

STN. ‘B’ STN ‘A’ LSS OF FSS OF STN.A STN.B

Block Section to be Adequate kept clear Distance

Before granting Line Clear SM should ensure that

- the whole of the last preceding train has arrived completely

- all the necessary signals have been put back to ON position

behind the said train.

Complete arrival of the train is checked by CAMTECH/S/2001/Basic Concepts/SCR-4 66

- physical verification with LV board / tail lamp

- provision of last vehicle check device.

- Continuous track circuits.

- Axle counters, etc.

Ensuring signals put back to ON is done by

- providing reverses on mechanically operated Semaphore

signals.

- Through arm type circuit controllers, relays etc.

- In case of colour light signals through relays.

- By treadles or track circuits.

Automatic block system on double line :

Essentials of Automatic Block System :

1. Provision of continuous track circuits or axle counters

2. Line between two stations is divided into a series of sections known as

automatic block signaling sections.

3. Entry into each block section is protected by a Colour light stop signal.

4. Track circuits/axle counters should control the aspects of such signals.

- It cannot display yellow aspect – unless one block section and

overlap are clear.

- Double yellow aspect - unless two block sections and overlap

are clear.

- Green aspect – unless three block sections and overlap are

clear. CAMTECH/S/2001/Basic Concepts/SCR-4 67

- Signal is replaced to ON automatically soon after the passage of

the train.

5. Where three aspect signals are provided double yellow (second yellow

provided on the top) is dispensed with.

6. ‘A’ markers are provided below the colour light signals.

>II> I> I>

Overlap Berthing Overlap Overlap Overlap track Block Section Block Section Block Section

>I >II> I>

Overlap Overlap Overlap Overlap Block Section

Manual & Semi-automatic signals :

¾ Manual controls can be introduced for any special purpose. They are then

called Manual signals.

¾ Manual controls introduced or removed at are known as Semi-automatic

signals.

¾ They can be worked either as automatic mode or manual mode.

‘A’ Marker signals :

Under normal circumstances, there is no need to distinguish between manual, automatic or semi-automatic signals. In case of failure procedure for passing of manual signal is different from passing signals at ON in automatic territory.

• In manual signaling – authority to pass the signal at ON is required to be

given to the driver of the train to pass. CAMTECH/S/2001/Basic Concepts/SCR-4 68

• In case of automatic signaling – there are no stations and SM to give such

authority to proceed. Hence, there is a different procedure for passing

such signals at ON.

Procedure for passing signals at ON in automatic signaling :

1. The driver has to bring the train to a dead stop.

2. Then, wait for one minute by day and two minutes by night.

3. Then, proceed cautiously at such low speed so as to able to stop short of

any obstruction at short notice.

4. Only after ensuring that the track ahead is in tact.

5. He should arrange guard or assistant driver to walk ahead with hand

signals.

The train must resume normal speed after passing the ‘OFF’ aspect of the signal in advance.

Since procedures for passing signals at ON is different for automatic and manual signaling modes, it is necessary to inform the driver whether the signals of that particular moment are in automatic mode or manual mode in semi-automatic mode; therefore, ‘A marker lit’ is used in case of automatic mode. If ‘A’ marker extinguishes, then the driver will know that signals are working manually and he will follow the rules regarding manual working for passing signal at ON. CAMTECH/S/2001/Basic Concepts/SCR-4 69

Gate Signals :

Automatic signals interlocked with level crossing gates are distinguished by

the provision of ‘G’ marker’, yellow enameled disc with a letter ‘G’ in black in

addition to an illuminated ‘A’ marker. ‘A’ marker light is lit only if the gates are

closed and locked against road traffic.

Procedure for passing the gate signal at ON :

With ‘A’ marker light lit – same procedure for an automatic signal displaying

the Red aspect.

With ‘A’ marker light extinguished

- wait for one minute by day and two minutes by night

- draw the train continuously ahead and stop of the gate

- ensure that the gates are locked against road traffic and after

getting hand signal from gate man, proceed cautiously up to the

signal in advance.

Automatic Block Signaling on Single Line :

The main purpose of this system is to increase the section capacity by

reducing the headway between two consecutive trains moving in the same

direction.

The system is particularly suitable in a single line where pattern of traffic is

such that trains follow one another in quick succession during certain parts of the day. CAMTECH/S/2001/Basic Concepts/SCR-4 70

Essentials of automatic block system on Single line :

1. The line shall be provided with continuous track circuits or axle counters.

2. The direction of traffic shall be established only after line clear has been

obtained from block section in advance.

3. The train shall be started from one block section to another only after the

direction of the traffic has been established.

4. It shall not be possible to obtain line clear unless the line is clear not only

up to the first stop signal but also for an adequate distance beyond it.

5. The line between two adjacent stations is divided into two or more

automatic block signaling sections by provision of stop signals.

6. The movement of trains in automatic block signaling is controlled by

automatic stop signals.

7. All stop signals against the direction of the traffic shall be maintained at

ON.

Automatic Block Signalling Section

DN >

< UP

Automatic Block Signalling Section CAMTECH/S/2001/Basic Concepts/SCR-4 71

Minimum equipment of fixed signals :

- Manual stop signals at a station Home and Starter.

- An automatic stop signal in rear of Home signal

- Additional automatic signals as may be necessary in between

block section.

Description of Panel :

¾ A control panel is provided at every station of automatic signaling section.

¾ Each station controls the movements of trains in one adjacent section.

¾ Two illuminated arrows for each direction. When direction of traffic is

established, arrow gets illuminated White when line is clear. It changes to

Red when block section is occupied or due to failure of track circuit / Axle

counter.

¾ Signal normal indication to prove that signals of that side of station are at

ON.

¾ Permission from (green indication) to indicate pressing of Push button at

the controlling section.

¾ Direction switch to establish the direction of traffic.

¾ SMs lock up key – to lock up the panel in the last operated position to

prevent unauthorised or inadvertent operation.

¾ Emergency push buttons to permit change of direction of traffic in case of

failure of track circuit / axle counter.

¾ Counters (digital) to register each operation of emergency switches. CAMTECH/S/2001/Basic Concepts/SCR-4 72

Rules for passing the automatic signals at ON :

♦ To bring the train to a stop in rear of signal.

♦ Wait one minute by day and two minutes by night.

♦ Driver to contact the section controller or SM of adjacent block section on

telephone near the signal.

♦ To proceed cautiously only after being authorised to pass signal at ON.

♦ If no telephone / telephone has failed, driver to proceed after giving code

whistle to guard up to next stop signal in advance.

♦ Be prepared to stop at short of signal.

Following Trains System :

Where trains are worked on the following trains system, they may be dispatched from one station to the next following each other in succession in the same direction on the same line in such manner and at such intervals of time as may be prescribed by special instructions.

Trains shall not be worked on the following trains system unless the SM of the block station in advance has exchanged messages regarding his readiness to receive the trains and has in addition, given his assurance that no train will be allowed to leave his station for the station from which the following trains are to be dispatched, until the latter have all arrived at his station and until he has received permission to dispatch trains in the opposite direction. CAMTECH/S/2001/Basic Concepts/SCR-4 73

Pilot guard system :

Where trains are worked on the pilot guard system

a) A railway servant shall specially deputed to pilot trains; and

b) No train shall leave a station except under the personal authority of the

pilot guard.

The trains shall not follow one another in the same direction between stations,

unless :

♦ The driver has been properly warned of the time of departure of the

proceeding train and of the place at which it will next stop.

♦ All the trains are timed to run at the same speed shall not exceed 25 kmph

except under special instructions.

♦ An interval of fifteen minutes has elapsed since the departure of the

proceeding train.

The train staff and Ticket system :

Where trains are worked between two stations on the Train-staff and Ticket system.

a) A single Train – staff shall be kept at one of such stations

b) No train shall start from either of such stations to the other unless the said

Train-staff is at the station from which the train starts and has either been

handed to or shown to the driver by the station master when giving such

permission. CAMTECH/S/2001/Basic Concepts/SCR-4 74

Trains shall not follow one another in the same direction between train – staff

stations, unless :

i. The driver has been properly warned of the time of departure of the

preceding train and of the place at which it will next stop.

ii. All the trains are timed to run at the same speed, and such speed shall

not exceed 25 kmph except under special instructions, and

iii. An interval of fifteen minutes has elapsed since the departure of the

preceding train.

The One train only system :

Trains may be worked on the One train only system, only on short terminal branches on the single line.

Where trains are worked on the one train only systems, only one train shall be

on the section on which this system in force at one and the same time.

A driver shall not take his train into the section unless he is in possession of

the authority to proceed.

Control of Outlying sidings:

Sidings taking off from running lines and located between block stations

known as outlying or intermediate sidings.

Minimum equipment required :

Facing Point Lock :A gauge tie plate where steel sleepers are not provided.

Facing point lock or equivalent mechanism. Plunger shall

lock each switch independently. CAMTECH/S/2001/Basic Concepts/SCR-4 75

Speed Restriction :Speed Restriction of 50 KMPH on running lines over

facing point.

Where sectional speed is more than 50 kmph S marker

to be provided.

In addition a caution and termination indicator shall also

be provided.

Points control through Block Instruments :

The points should be controlled through the block system in use only in the

case of facing points on the single line as well as in the case of double line

trailing points.

The points normally set and locked for the running line are released by token / by key interlocking boxes and electrically transmitted keys.

At station X a token key interlocking box with a spare token locked in it and at

the siding, a similar box, but with the points key locked in it are provided.

An EKT circuit is provided between station X and the siding, a key is locked in

the EKT at X and there is no key in the EKT at siding.

A train proceeds from X or Y with a token and is stopped at the siding and the

token is exchanged for the points key on the token key interlocking box, the

points key is used to unlock the points, the train then enters siding.

The points are then reset in normal, and after ensuring that the running line is

clear, the key is transmitted to X to clear the section.

For the train to come out of siding, the guard informs X on the telephone. X

obtains a token, exchanges it for the key and transmits the key to the siding. CAMTECH/S/2001/Basic Concepts/SCR-4 76

The key is used for unlocking the siding points, the train enters the running line, the points are reset to normal and key released from the points exchanged for the token originally deposited in the token key – interlocking box.

The train proceeds with the token to either X or Y.

Disadvantages : Only one train can be dealt with in the siding at a time.

On the double line, the block instrument can not be restored to the normal

position until the train is received at the receiving end.

Interlocking may, however, be provided between the block instrument and the

points so that the points can not be unlocked with out the block instruments

being in TOL position.

When it is necessary to clear the block section, when train has entered the

siding, the intermediate siding is worked as block station and switched out

when the use of the siding is not required.

However, where double line block instruments which provide for an

occupation key to enable trains to enter block section in the right direction and

return to the same station.

The occupation key when removed locks the key in normal position.

In such cases, the occupation key can be used for sending trains into intermediate siding and section cleared after the train is berthed in the siding.

The train can only return to the station from which it entered into the block

section travelling in the wrong CAMTECH/S/2001/Basic Concepts/SCR-4 77

ON SINGLE LINE 050 50 • SIDING • S RUNNING T LINE

TRAIN MINIMUM 800 M 30 M LENGTH

on double line s

• SIDING • S T

RUNNING LINE

MINIMUM 800 M 30 M

trailing point on double line

SIDING S

RUNNING LINES CAMTECH/S/2001/Basic Concepts/SCR-4 78

General : To avoid unauthorised interference, all bolts, studs, pins etc of apparatus used for blocking and control of siding points are revetted or otherwise adequately secured.

In view of the rule that isolation must be provided, and the isolating traps locked for all movements on the running lines at all outlying sidings. A trap indicator has to be provided but it is not lit during night hours.

Station Working Rules (SWR) :

1. The object of SWR is to regulate safe working of traffic in and between

stations depending on the local conditions that exist at the station.

2. The SWR are intended to draw attention of the staff concerned to the rules

for giving line clear, taking OFF signals, reception and dispatch of trains,

working of level crossing gates, shunting, stabling of vehicles on the

running lines, etc. and also instructions regarding working during failure of

points , signals, interlocking, communications etc.

3. SWR should be self contained, brief to the point and in unambiguous

language.

4. General and subsidiary rules and block working manual rules should not

be extracted in SWR. Relevant rule numbers of G & SR, block-working

manual may be mentioned.

5. DSO, DSTE and DEE are empowered to issue, modify SWR.

6. SWR should be reviewed once in three years or three amendment slips

whichever is earlier. CAMTECH/S/2001/Basic Concepts/SCR-4 79

7. All the staff required to take up independent duties at the stations shall

sign a declaration register to the effect that they have read and understood

the SWR.

8. Fresh declaration shall be obtained from the staff concerned in the

following cases :

(a) An amendment is issued to SWR

(b) An employee is absent consecutively for more than 15 days.

9. SWR contains twelve paras and six appendices. They are :

(a) Signaling Plan (Diagram)

(b) Description of station

(c) Systems and means of working

(d) Systems of signaling and interlocking

(e) Telecommunications

(f) Trains working

(g) Blocking lines

(h) Shunting

(i) General instructions

(j) Visibility test object

(k) Essential equipment

(l) Names of Fog signal men

Appendices :

A - Working of level crossing gates

B - Systems of signaling and interlocking

C - Telecommunications CAMTECH/S/2001/Basic Concepts/SCR-4 80

D - Duties of staff

E - Essential equipment

F - Names of fog signal men

Signaling Plan

Taking the operating features in to consideration, engineering department

prepares the engineering plan and sends it to S & T department for preparation of signaling plan. Signaling department taking all gradients’ level crossing gates, cabins, etc., prepares signaling plan for arranging signaling equipment.

The signaling plan consists of :

1. Permanent way plan along with levels and gradients

2. Types of signals to be provided

3. Location of signals with reference to point or level crossing

4. Classification of station-wise – class A,B,C etc.

5. Standard of interlocking

6. Decide the size of lever frame for operation of each function and also

consider for space to be provided to cater for the future.

7. Interlocking plan number

8. Location of cabin … Points, LC gates.

After preparing Signaling plan, shall be sent to CRS for approval. The work

should be carried out as per approved signaling plan. Any alteration in the

signaling plan should not be carried out without the approval of CRS.

Signaling plan with IP number should be exhibited at the station’s office, in the

cabin of bigger size for instant visibility. CAMTECH/S/2001/Basic Concepts/SCR-4 81

DESIGNATION & LOCATION OF FIXED SIGNALS IN TWO ASPECT LQ SIGNALLING

RECEPTION END DESPATCH END WARNER ON A POST BY ITSELF HOME STATION UP DN LSS

NBD : 1200 M NOT LESS THAN BOL 400 M TS

BRACKETED HOME UP DN WARNER BELOW WARNING OUTER BOARD

1 KM SOL NBD BOL 180 M 400 M

STARTER

OUTER HOME WARNING WARNER BOARD

BOL 400 MTS

ADV STARTER

1 KM

STARTER SOL 180 MTS CAMTECH/S/2001/Basic Concepts/SCR-4 82

FOR FIGURE PLEASE CLICK HERE CAMTECH/S/2001/Basic Concepts/SCR-4 83

Question Bank : Subjective :

1. a) Draw a 3-road station B class layout on single line section. Provide

signaling arrangement for two-aspect lower quadrant working.

b) indicate the block overlap and signal overlap ?

2. what are the conditions for taking OFF Warner signal and for what speed

Warner is to be taken OFF ?

3. What are the rules for providing a calling on signal and when it can be

taken OFF ?

4. What are subsidiary signals? Give examples ?

5. Explain briefly on isolation, braking distance sighting distance ?

6. Write short notes on any three of the following

a) Shunting limit board

b) Block section limit board

c) Slip and catch siding

d) Classification of stations

7. Explain with sketches various markers used in signaling ?

8. What are classification of stations and what are the minimum equipments

of signals required for each class ?

9. Write short notes on any three of the following :

a) Signal overlap

b) Block overlap

c) Calling ON signal

d) Shunt signal

e) Repeating signal CAMTECH/S/2001/Basic Concepts/SCR-4 84

10. Draw a single line B class station with MACLS having simultaneous

reception facilities ? Mark all the inter signal distances.

11. Draw a class B 4 road stations with a common loop facility on double line

section to standard III interlocking MAUQ signaling and indicate the inter

distance ?

12. What is meant by isolation ? What are the rules for isolation ?

13. a) What are the principles of interlocking?

b) Write the Minimum equipments to be provided for STD-1 and STD-III

interlocking.

14. What are the differences between a shunt signal and calling on signal,

distant and Warner signals.

15. Make out a sketch for interlocking on intermediate siding in a single line

with out speed restriction and the sectional speed is 100 km. Describe the

working of siding.

16. What are essentials of Automatic Block Working

17. Write short note on any four of the following;

a) Illuminated A marker

b) Co-acting signal

c) Isolation

d) Point & trap indicator

e) Inter-cabin control.

18. What are essentials of Absolute Block System ?

19. What are the requirements of various STDs of interlocking ?

20. Write short notes on any four of the following:

a) Automatic gate signal CAMTECH/S/2001/Basic Concepts/SCR-4 85

b) Simultaneous reception

c) Station limit and station section

d) Station and a block station

e) Block forward and block back

f) Running train and train

Objective :

Fill in the blanks :

1. The F.S.S in a MACLS Std-III station is ______.

2. The maximum speed permitted over the points for straight-line fitted with

standard III fittings is ______.

3. The distance traveled by a train after its brakes are applied is called

______.

4. The distance sufficient to ensure safety is called ______.

5. The place at which the railway line across the road is called

______.

6. Shunting in the face of an approaching train is permitted at station

______.

7. Block overlap at a 3 aspect section is ______

8. What is the meaning of CRS ______

9. G marker is painted with ______colour background and

______colour letter.

10. Shunt signals should not be provided on ______signals.

11. CRS means ______. CAMTECH/S/2001/Basic Concepts/SCR-4 86

12. CSR means ______.

13. Shunt signal below a stop signal when at ON displays

______.

14. An independent Warner during night when taken OFF displays two

______lights one below the other.

15. Signal overlap in multiple aspect signaling is ______.

16. In two aspect signaling advanced starter is located not less than

______from the top point.

17. Distance between advanced starter and the opposite home signal on

single line MAUQ is ______.

18. A calling on signal is provided with ______.

19. When a block station is approached on a steep falling gradient

______is provided.

20. Normal aspect of distant signal is ______.

21. Normal aspect of inner distant signal is ______.

22. Minimum visibility for distant signal required is ______.

23. In LQ territory block overlap is ______.

24. Calling on signal at ON position display ______.

25. The light shown by a point indicator when set to straight line is

______and a trop indicator when it closed

______.

26. The station limits in a MAUQ class B station is demarcated by

______signals.

27. The minimum visibility for all UQ signals is ______

meters. CAMTECH/S/2001/Basic Concepts/SCR-4 87

28. A gate cum distance signal will have ______number of aspects.

29. The warning board shall normally be fixed at ______

meters from FSS.

30. In LQ signaling a gate signal protecting mid section on level crossing gate

shall be located minimum ______from the gate.

Choose the Correct Answer :

1. Signal Overlap in Two aspect territory [ ]

a) 120 Mts. b) 180 Mts. c) 400 Mts. d) 600 Mts.

2. The speed of a train t pass via loop at Std-III interlocking station is

a) 15 Kmph b) 25 Kmph c) 50 d) none [ ]

3. Route indicators are treated as [ ]

a) stop signals b) signal device c) subsidiary d) none

4. A post type CLS shut signal at ON position displays [ ]

a) 2 light horizontally b) 2 lights inclined at 450 to left c) two lights

5. Isolation of main line from adjoining lines shall be provided if speeds on

main lines exceeds [ ]

a) 15Kmph b) 50Kmph c) 75 Kmph d) none

6. Visibility of man line starter in MACLS is [ ]

a) 400 Mts b) 300 Mts c)200 Mts d) none

7. Maximum equipment of signals at a class A station are [ ]

a) Outer, Warner, Home b) Warner, Home, Starter

c) Outer, Home, Starter d) none CAMTECH/S/2001/Basic Concepts/SCR-4 88

8. The signal painted with red band is called [ ]

a) Co-acting signal b) Repeating signal c) calling ON signal d) none

9. A colour light repeating signal when it will display [ ]

a) Red light b) Yellow light c) Miniature Yellow d) none

10. The minimum visibility of an outer signal should be [ ]

a) 400 Mts b) 200 Mts c) Full breaking d) none

11. In LQ signaling, run through indication is given by [ ]

a) Home Signal b) Warner Signal c) Advance Starter d) none

12. Isolation of goods reception lines from one another is [ ]

a) Compulsory b) Desirable c) Not required d) None of these

13. The minimum distance between home and outer on double line LQ

signaling is [ ]

a) 580 Mts b) 1 Km c) 400 Mts d) none

14. The distance signal (where double distance is working in force) is located

at [ ]

a) 1.4 km from home b) 2 km from home c) 1.4 km from inner distant

d) None

15. The first stop signal of class A station [ ]

a) Outer b) Warner c) Home d) None

16. Minimum distance required between distant and home signal in MAUQ

signaling on single line is [ ]

a) 1400 Mts. b) 1000 Mts. c) 1200 Mts. d) None

17. Shunting limit board is provided only in [ ]

a) Class A station on single line b) class A station on Double line

c) Class B station on single line d) None CAMTECH/S/2001/Basic Concepts/SCR-4 89

18. Block section limit board is provided at certain station on [ ]

a) Double Line section b) Both single and double line station

c) MAUA territory d) None of these

19. P marker is provided on [ ]

a) All distant signals b) All distant signals in CLS area

c) All permissive signals d) None

20. Warner signal located below a stop signal is capable of displaying

a) 3 aspects b) 2 aspects c) 4 aspects d) None [ ]

21. Calling ON signal can only be located [ ]

a) below a stop signal b) below a starter signal c) below a LSS

d) None

22. Shunting in the face of an approaching train up to shunting limit board is

permitted in [ ]

a) Class A b) Class B c) Class C d) None

23. The adequate distance for an automatic signal to clear in a single line

when the next signal in advance in an automatic signal is [ ]

a) 400 Mts. b) 180 Mts. c) 120 Mts. d) zero Mts.

24. An automatic stop signal is distinguished by [ ]

a) A marker disc b) A marker light c) P marker disc

d) AG marker disc. CAMTECH/S/2001/Basic Concepts/SCR-4 90

Say TRUE or FALSE

1. Whenever main home and outer are taken OFF Warner can be taken OFF

[ ]

2. All distant signals will be fitted with P marker [ ]

3. Warner shall always be fixed below the FSS [ ]

4. S marker is provided at siding taken OFF from running line in block

section. [ ]

5. For speeds above 50 kmph and below 75 kmph std-II interlocking shall be

provided. [ ]

6. The block overlap in C class station is 180 Mts. [ ]

7. Post type shunt signal will display both ON and OFF aspects [ ]

8. Plunger lock detection is not necessary for STD-III interlocking [ ]

9. Calling on signal has no independent location [ ]

10. A catch siding shall be provided at stations where the station is

approaching a steep falling gradient [ ]

11. At a class A station line clear shall not be granted for a train of the line is

clear up to the home signal. [ ]

12. LSS can be used as shunting signal [ ]

13. A shunting limit board need not be lit during night [ ]

14. Block overlap in BG is more than that in MG [ ]

15. In multiple aspect territory warning board is not necessary when the

distant signal is placed at 1 km from the home. [ ]

16. Shunting limit boards are provided only on single line [ ] CAMTECH/S/2001/Basic Concepts/SCR-4 91

17. In colour light signaling, junction indicator is used so as to avoid speed

restriction. [ ]

18. A co-acting signal can be located on a separate post by itself [ ]

19. A point indicator displays a red light during night when the points are set

for the turn out. [ ]

20. All block systems required an authority to proceed [ ]

21. B class LCs must normally be kept closed for road traffic [ ]

22. Lock detection is not mandatory in STD-III interlocking when points and

lock are worked by separate levers [ ]

23. Generally class A stations are provided with STD-III interlocking only

[ ]

24. In CLS, junction indicator is used so as to avoid speed restriction.

[ ]

Match the following :

[ ] 1. Block Overlap a) 2 aspect

[ ] 2. Signal Overlap b) Isolation

[ ] 3. Warner Signal c) 15 kmph

[ ] 4. Repeating Signal d) Station section

[ ] 5. Clamp and Pad Lock e) On Single Line only

[ ] 6. Class B Station f) Double Line

[ ] 7. Trap Siding g) 120 Mts.

[ ] 8. BSLB h) Calling ON

[ ] 9. SLB i) 400 Mts. CAMTECH/S/2001/Basic Concepts/SCR-4 92

[ ] 10. C Marker j) Station section

[ ] 1. Railway Safety a) Automatic Stop Signal

[ ] 2. G Marker b) Double Line

[ ] 3. A. Marker c) Single Line

[ ] 4. H P Lock d) Sand Hump

[ ] 5. P L C e) Calling on Single

[ ] 6. P I C f) only in two aspect

[ ] 7. Isolation g) CLS distant

[ ] 8. No ON aspect h) Gate signal

[ ] 9. A Class station i) Hand operated point

[ ] 10. P Marker j) CRS

[ ] 1. A Class Station a) Goods line reception

[ ] 2. A Marker light b) Repeater signal

[ ] 3. R Marker c) 400 Mts. form home

[ ] 4. Fixed green light over the post d) Isolation

[ ] 5. Outer Signal on double line e) Semi automatic signal

[ ] 6. Visibility of MA Stop Signal f) Only in T.A

[ ] 7. O Marker g) Warner

[ ] 8. Trap Point h) 400 Mts.

[ ] 9. Distant signal proceed aspect i) 180 Mts. from outermost

point

[ ] 10. 1st stop signal on double j) Received on main line

line in MAUQ