The automatic block system
(Extract from IR General Rules : Chapter 9)
A. Rules applicable to Double Line
9.01 Essentials of the Automatic Block System on double line.
(1) Where trains on a double line are worked on the Automatic
Block System,
(a) the line shall be provided with continuous track
circuiting or axle counters
(b) the line between two adjacent block stations may,
when required, be divided into a series of automatic
block signalling sections each of which is the portion of
the running line between two consecutive Stop signals,
and the entry into each of which is governed by a Stop
signal, and
(c) the track circuits or axle counters shall so control
the Stop signal governing the entry into an automatic
block signalling section that -
(i) the signal shall not assume an 'off' aspect
unless the line is clear not only upto the next
Stop signal in advance but also for an adequate
distance beyond it, and
(ii) the signal is automatically placed to 'on' as
soon as it is passed by the train.
(2) Unless otherwise directed by approved special instructions,
the adequate distance referred to in sub-caluse (i) of clause
(c) of sub-rule (I) shall not be less than 120 metres.
9.02 Duties of Driver and Guard when an automatic Stop signal on
double line is to be passed at 'on'
(1) When a Driver finds an Automatic Stop signal with an 'A'
marker at 'on', he shall bring his train to a stop in the rear
of the signal. After bringing his train to a stop in the rear
of the signal, the Driver shall wait there for one minute by
day and two minutes by night. If after waiting for this period,
the signal continues to remain at 'on', he shall give the
prescribed code of whistle and exchange signals with the Guard
and then proceed ahead, as far as the line is clear, towards
the next Stop signal in advance exercising great caution so as
to stop short of any obstruction.
(2) The Guard shall show a Stop hand signal towards the rear
when the train has been so stopped at an Automatic Stop signal,
except as provided for in sub-rule (4).
(3) Where owing to the curvature of the line, fog, rain or dust
storm, engine working the train pushing it, or other causes,
the line ahead cannot be seen clearly. The Driver shall proceed
at a very slow speed, which shall under no circumstances exceed
8 kilometres an hour. Under these circumstances, the Driver,
when not accompanied by a Fireman or an Assistant Driver, and
if he considers necessary, may seek the assistance of the Guard
by giving the prescribed code of whistle.
(4) When so sent for by the Driver, the Guard shall accompany
him on the engine cab, before he moves forward, to assist the
Driver in keeping a sharp look-out.
(5) When an Automatic Stop signal has been passed at 'on', the
Driver shall proceed with great caution until the next Stop
signal is reached. Even if this signal is 'off', the Driver
shall continue to look out for any possible obstruction short
of the same. He shall proceed cautiously upto that signal and
shall act upon its indication only after he has reached it.
B. Rules applicable to Single Line
9.03 Essentials of the Automatic Block System on single line
(1) Where trains on a single line are worked on the Automatic Block System
(a) the line shall be provided with continuous
track circuiting or axle counters,
(b) the direction of the traffic shall be
established only after Line Clear has been obtained
from the block station in advance.
(c) a train shall be started from one block station
to another only after the direction of traffic has
been established.
(d) it shall not be possible to obtain Line Clear
unless the line is clear, at the block station from
which Line Clear is obtained, not only upto the
first Stop signal but also for an adequate distance
beyond it.
(e) the line between two adjacent block stations
may, where required, be divided into two or more
automatic block signalling sections by provision of
Stop signals.
(f) after the direction of traffic has been
established, movement of trains into, through and
out of each automatic block signalling section
shall be controlled by the concerned Automatic Stop
signal and the said Automatic Stop signal shall not
assume 'off' position unless the line is clear upto
the next Automatic Stop signal : provided further
that where the next Stop signal is a Manual Stop
signal, the line is clear for an adequate distance
beyond it, and
(g) Unless otherwise directed by approved special
instructions, the adequate distance referred to in
clauses (d) and (f) of sub-rule (1) shall not be
less than 180 metres.
9.04 Minimum equipment of fixed signals in Automatic Block territory
on single line
The minimum equipment of fixed signals to be provided for each
direction shall be as follows
(a) Manual Stop signals at a station
(i) a Home
(ii) a Starter
(b) An Automatic Stop signal in rear of the Home signal
of the station.
Note: Under approved special instructions, the Automatic
Stop signal may be dispensed with.
9.05. Additional fixed signals in Automatic Block territory on single
line
(1) Besides the minimum equipment prescribed in Rule 9.04, one
or more additional Automatic Stop signals, as are considered
necessary, in between block stations, may be provided.
(2) In addition, such other fixed signals as may be necessary
for the safe working of trains may be provided.
9.06 Conditions for taking 'off' Manual Stop signals in Automatic
Block territory on single line
(1) Home signal - When a train is approaching a Home signal,
otherwise than at a terminal station, the signal shall not be
taken 'off' unless the line is clear not only upto the Starter
but also for an adequate distance beyond it.
(2) Last Stop signal - The last Stop signal shall not be taken
'off' for a train unless the direction of traffic has been
established and the line is clear upto the next Automatic Stop
signal, or when the next Stop signal is a Manual Stop signal
for an adequate distance beyond it.
(3) The adequate distance referred to in sub-rules (1) and (2)
shall never be less than 120 metres and 180 metres respectively
unless otherwise directed by approved special instructions. A
sand hump of approved design, or subject to the sanction of the
Commissioner of Railway Safety, a derailing switch shall be
deemed to be an efficient substitute for the adequate distance
referred to in sub-rule (1).
9.07. Duties of Driver and Guard when an Automatic Stop signal on
single line is to be passed at 'on'
(1) When a Driver finds an Automatic Stop signal with an 'A'
marker at 'on', he shall bring his train to a stop in rear of
that signal and wait there for one minute by day and two
minutes by night.
(2) If after waiting for this period the signal continues to
remain at 'on', and if telephone communication is provided near
the signal, the Driver shall contact the Station Master of the
next block station or the Centralised Traffic Control Operator
of the section where Centralised Traffic Control is provided,
and obtain his instructions. The Station Master or the
Centralised Traffic Control Operator, as the case may be,
shall, after ascertaining that there is no train ahead upto the
next signal and that it is otherwise safe for the Driver to
proceed so far as is known, give permission to the Driver to
pass the signal in the 'on' position and proceed upto the next
signal, as may be provided under special instructions.
(3) If no telephone communication is provided near the signal
or if the telephone communication provided near the signal is
out of order and cannot be made use of, the Driver shall give
the prescribed code of whistle and exchange signals with the
Guard and then proceed past the signal as far as the line is
clear, upto the next Stop signal in advance, exercising great
caution so as to stop short of any obstruction.
(4) The Guard shall show a Stop hand signal towards the rear
when the train has been so stopped at an Automatic Stop signal,
except as provided for under sub-rule (6).
(5) Where owing to the curvature of the line, fog, rain or dust
storm, engine working the train pushing it, or other causes,
the line ahead cannot be seen clearly, the Driver shall proceed
at a very slow speed, which shall under no circumstances exceed
8 kilometres an hour. Under the circumstances, the Driver when
not accompanied by a Fireman or Assistant Driver, and if he
considers it necessary, may seek the assistance of the Guard by
giving the prescribed code of whistle.
(6) When so sent for by the Driver, the Guard shall accompany
him on the engine cab, before he moves forward, to assist the
Driver in keeping a sharp look-out.
(7) When an Automatic Stop signal has been passed at 'on', the
Driver shall proceed with great caution until the next Stop
signal is reached. Even if this signal is 'off', the Driver
shall continue to look out for any possible obstuction short of
the same. He shall proceed cautiously upto that signal and
shall act upon its indication only after he has reached it.
9.08. Person in charge of working trains on Automatic Block System on
single line
(1) Except where Centralised Traffic Control is in operation,
the Station Master shall be responsible for the working of
trains at and between stations.
(2) On a section where Centralised Traffic Control is in
operation, the Centralised Traffic Control Operator shall be
responsible for the working of trains on the entire section
except as provided for in sub-rule (3).
(3) On a section where Centralised Traffic Control is in
operation, the working of trains at a station or part of a
station may be taken over by or handed over to the Station
Master during emergency or as prescribed by special
instructions. When such emergency control is transferred, the
Station Master shall be the person in charge of working trains
at the station or part of the station and the station shall be
worked in accordance with sub-rule (1).
C. Rules applicable to both Double and Single Lines.
9.09 Working of trains on Centralised Traffic Control territory
On a section where Centralised Traffic Control is in operation,
the working of trains shall be governed by special
instructions.
9.10 Protection of a train stopped in an Automatic block signalling
section
(1) When a train is stopped in an Automatic block signalling
section, the Guard shall immediately exhibit a Stop hand signal
towards the rear and check up that the tail board or tail light
is correctly exhibited.
(2) If the stoppage is on account of accident, failure, or
obstruction and the train cannot proceed, the Driver shall
sound the prescribed code of whistle and the train shall be
protected immediately as per Rule 6.03 except that for the
protection of the occupied line one detonator shall be placed
at 90 metres from the train on the way out and similarly two
detonators, 10 metres apart, not less than 180 metres from the
train or at such distances as has been fixed by special
instructions.
9.11 Driver to report failures
(1) When as Driver has to pass an Automatic Stop signal at
'on', he shall stop his train at the next reporting station or
cabin as prescribed by special instructions and report
particulars of Automatic Stop signals passed at 'on' by him.
(2) The Station Master or person in charge of the reporting
station or cabin shall promptly report the fact to the signal
and operating officials concerned.
9.12 Procedure during failure of Automatic signalling
When a failure of Automatic signalling is likely to last for
some time or cause serious delay, trains shall be worked from
station-to-station over the section or sections concerned under
special instructions.
9.13 Movement of trains against the direction of traffic on the
Automatic Block System
In Automatic signalling territory, trains shall run in the
established direction of traffic only. Movement of trains
against the established direction of traffic is not
permitted. When in an emergency it becomes unavoidably
necessary to move a train against the established direction of
traffic, this shall be done only under special instructions
which shall ensure that the line behind the said train upto the
station in rear is clear and free from obstruction.
9.14 Procedure when Semi-Automatic Stop signal is 'on'
(1) When a Semi-Automatic Stop signal is worked as an Automatic
Stop signal, Rule 9.02 or 9.07 shall apply as the case may be.
(2) When a Semi-Automatic Stop signal is working as a Manual
Stop signal and becomes defective, it may only be passed under
relevant rules detailed in Chapter III, Section 'H'.
(3) When a Driver is authorised to pass a Semi-Automatic Stop
signal at 'on' by taking 'off' the Calling-on signal fixed
below it, he shall follow the precautions stipulated in Rule
9.02 or 9.07 as the case may be.
9.15 Passing a gate Stop signal at 'on' in Automatic signalling territory
If the Driver finds a gate Stop signal at 'on' in an Automatic
signalling territory
(a) he shall comply with the provisions of Rule 9.02 or
9.07 as the case may be, if the 'A' marker is
illuminated, or
(b) if the 'A' marker light is extinguished, he shall
sound the prescribed code of whistle to warn the Gateman
and bring his train to a stop in rear of the signal. If
after waiting for one minute by day and two minutes by
night, the signal is not taken 'off', he shall draw his
train ahead cautiously and stop in rear of the level
crossing. After ascertaining that the gates are closed
against the road traffic and on getting hand signals from
the Gateman, and in his absence from Fireman or Assistant
Driver, the Driver shall sound the prescribed code of
whistle and cautiously proceed upto the next Stop signal
complying with the provisions of Rule 9.02 or 9.07 as the
case may be; in the absence of the Fireman or Assistant
Driver, this duty shall devolve upon the Guard.
