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.


The material on this page is extracted from Indian Railways General Rules (Open Lines), 1976, published by the Government of India.
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