Automatic Block Signalling - General
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Questions and Answers

What characterizes Manual Stop Signals?

  • They can operate without a fixed signal.
  • They can only function in an automatic mode.
  • They require manual control each time they are taken 'OFF'. (correct)
  • They can be operated automatically without manual intervention.

    • Which statement is true regarding Semi-Automatic Stop Signals?

  • They do not use track circuit controls.
  • They are incapable of manual operation.
  • They can be operated both automatically and manually as required. (correct)
  • They can only function as Automatic Stop Signals.

    • What happens to Manual Stop Signals when the section ahead is occupied?

  • They signal the operator to proceed without stopping.
  • They remain in the 'OFF' position.
  • They need to be manually reset to 'ON'.
  • They automatically switch to the 'ON' position. (correct)

    • What is the function of the control provided for Semi-Automatic Stop Signals?

    <p>To switch between automatic and manual operational modes.</p> Signup and view all the answers

    In a single line operation, what must be established according to GR 9.03?

    <p>Line clear and Direction of Traffic.</p> Signup and view all the answers

    What is the primary function of an Automatic Block System in train signalling?

    <p>To automatically control the movement of trains using Stop Signals.</p> Signup and view all the answers

    What determines the 'ON' position of a Stop Signal in an Automatic Signalling section?

    <p>The train passing into the signalling section.</p> Signup and view all the answers

    What is the minimum safe distance a line must be clear for an Automatic Stop Signal to switch to 'OFF' position?

    <p>120 metres, depending on signal type.</p> Signup and view all the answers

    When must an Automatic Stop Signal remain in the 'ON' position?

    <p>Until the train has passed the next Automatic Stop Signal and a further distance.</p> Signup and view all the answers

    What prohibits an Automatic signal from being switched to 'OFF' position?

    <p>Presence of another train on the same line.</p> Signup and view all the answers

    Which aspect of signal spacing is critical to avoid serious repercussions during signalling failures?

    <p>Distance should allow adequate braking distance without being excessive.</p> Signup and view all the answers

    How does the spacing of signals relate to a train's emergency braking distance?

    <p>Spacing must be regulated to ensure emergencies fit within signal distances.</p> Signup and view all the answers

    What regulates the speed of a train when the signal spacing is less than the emergency braking distance?

    <p>The speed must be regulated to fit within the emergency braking distance.</p> Signup and view all the answers

    What must Automatic Stop Signals exhibit when positioned against the direction of traffic?

    <p>'ON' position</p> Signup and view all the answers

    Which of the following is true regarding the provision of DC Track circuits in block sections?

    <p>They will not be provided due to maintenance issues</p> Signup and view all the answers

    What feature should the design of Axle Counters between adjacent stations include?

    <p>Individual track sections must have a resetting facility</p> Signup and view all the answers

    What type of indicator should be provided for Automatic Signalling on a Single Line?

    <p>A marker indicating section occupancy</p> Signup and view all the answers

    Which of the following describes the characteristics of markers for Automatic Stop Signals?

    <p>White disc with letter 'A' in black</p> Signup and view all the answers

    What is a key requirement for track circuits or axle counters on passenger running lines?

    <p>There should be no dead section between track circuits</p> Signup and view all the answers

    What mechanism should be implemented to improve availability in Track circuits or Axle Counters?

    <p>Redundancy</p> Signup and view all the answers

    What is the purpose of media diversity in relation to Axle Counters?

    <p>To ensure reliability of the detection system</p> Signup and view all the answers

    What should occur if a signal that must show a red aspect fails to do so?

    <p>The signal in rear should display a red aspect.</p> Signup and view all the answers

    What principle must all fail-safe circuits operate on?

    <p>Continuously energized principle.</p> Signup and view all the answers

    Under what condition can an automatic signal display the 'OFF' position?

    <p>Only if the track is clear up to the next signal and beyond.</p> Signup and view all the answers

    What must be proven before the 'A' marker of a Semi Automatic Signal lights up?

    <p>The signal must be working as an automatic signal.</p> Signup and view all the answers

    What happens if the lamp of the displayed aspect fails?

    <p>The signal will show the next restrictive aspect immediately.</p> Signup and view all the answers

    Which component should control the aspects of an automatic signal?

    <p>The main signal in advance.</p> Signup and view all the answers

    What is required for the 'AG' marker to light up when conditions are met?

    <p>The conditions for the 'A' Marker must be satisfied, except for specific levels.</p> Signup and view all the answers

    What information should be visible at the station regarding automatic signalling?

    <p>Signals aspects, track status information, and gate information.</p> Signup and view all the answers

    What is required before establishing the direction of traffic on a single line using the Automatic Block System?

    <p>Line Clear must be obtained from the block station in advance.</p> Signup and view all the answers

    What happens to the Automatic Stop signal after the direction of traffic has been established?

    <p>It only turns 'off' if the line is clear up to the next Automatic Stop signal.</p> Signup and view all the answers

    When can 'Line Clear' be obtained according to the Automatic Block System requirements?

    <p>If the line is clear for 180 metres beyond the first Stop signal.</p> Signup and view all the answers

    How can the direction of traffic be established in the Automatic Block System?

    <p>By control that prevents conflicting signals from being taken off.</p> Signup and view all the answers

    What must be ensured in the area between the two crossing stations before changing direction?

    <p>The entire line and overlap must be clear.</p> Signup and view all the answers

    What is the minimum adequate distance that must be clear for Line Clear to be obtained?

    <p>180 metres.</p> Signup and view all the answers

    What must happen to all Stop signals against the direction of traffic in the Automatic Block System?

    <p>They must be at 'on'.</p> Signup and view all the answers

    What is true regarding the division of the line between two adjacent block stations?

    <p>It can be divided into sub-sections with Stop signals where needed.</p> Signup and view all the answers

    What must happen to the ‘A’ marker of the Advanced Starter Signal when the modified semi-automatic stop signal is activated?

    <p>It must be extinguished.</p> Signup and view all the answers

    Under what conditions does the mid-section modified semi-automatic stop signal work normally?

    <p>During normal conditions.</p> Signup and view all the answers

    How many trains can be signaled simultaneously on either side of a mid-section modified semi-automatic stop signal?

    <p>One train on each side.</p> Signup and view all the answers

    What color scheme is used for painting the mid-section modified automatic signal?

    <p>Blue and white stripes.</p> Signup and view all the answers

    What provides indication of the signal's operational mode to the station masters?

    <p>Visual indications at both ends.</p> Signup and view all the answers

    What is the purpose of the interlocking system during mid-section modified automatic signalling?

    <p>To prevent exceeding train limits.</p> Signup and view all the answers

    What is required for the modified semi-automatic stop signal to function during abnormal conditions?

    <p>Extinguishing the ‘A’ marker.</p> Signup and view all the answers

    What aspect does the mid-section modified automatic signal depict when it is set to 'OFF'?

    <p>The signal's color and aspect based on other signals.</p> Signup and view all the answers

    Study Notes

    Automatic Block Signalling - General

    • Automatic Block Systems control train movement using stop signals. These signals automatically operate based on train passage.
    • Automatic stop signals are not manually operated but are controlled automatically as a train enters, goes through, and leaves a section.
    • Sections between stations are divided into smaller signalling sections.
    • Entry into each section is regulated by manual, automatic, or semi-automatic stop signals.
    • Signals must switch to the 'ON' position when a train enters a section and remain 'ON' until the train passes beyond the next signal and a safe distance.
    • Signals will only switch to the 'OFF' position when the section is clear, not just to the next signal, but a predetermined distance beyond it. This distance varies depending on whether the next signal is manual, semi-automatic, or automatic.
    • Signal spacing is crucial to ensure adequate braking distances for trains, preventing problems during failures or accidents.
    • Appropriate distances must be considered between signals to prevent issues with train braking distances.
    • Manual stop signals and semi-automatic stop signals require manual control to switch from 'On' to 'Off'.

    Special Requirements for Single Line

    • Single-line automatic block systems require line-clear procedures and established traffic directions, as defined by GR 9.03.
    • Continuous track circuits or axle counters are mandatory.
    • Traffic direction is established only after line-clear confirmation from the previous block station.
    • A train can only travel to the next block station after the direction of traffic is established.
    • Line clearance must verify not just the next signal, but also sufficient distance beyond for safety.
    • Signals prohibiting traffic in the opposite direction must remain 'ON'.
    • The minimum distance beyond the next signal must be at least 180m if the next is manual or semi-automatic.

    Train Detection and Markers

    • Train detection systems (track circuits/axle counters) are used to divide the line into sections for automatic signalling operation.
    • Track circuits/axle counters are required on passenger and other lines connecting stations in automatic sections, reducing dead zones.
    • Automatic stop signals have identifiable markers (white disc with letter ‘A’ in black).
    • Semi-automatic signals also have 'A' markers (illuminated white ‘A’ on a black background) when operating as automatic signals and additional 'AG' markers when needed to control gate signals or points.
    • A control system is used to establish direction of traffic and ensure conflicting signal operation cannot happen.
    • LED signals are recommended.
    • All external circuits should be able to be shut down for safety reasons.

    Maintenance and Modifications

    • Regular maintenance is required for LED signals, marker lights, track circuits, interlocking equipment, and axle counters.
    • Procedures for track renewal, equipment failures, or other aspects should be in place.
    • Under certain instructions, some automatic stop signals between stations can be modified for semi-automatic operation.
    • Modifying signals for semi-automatic use must address safety concerns related to train movements in abnormal conditions like fog.

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    Related Documents

    Automatic Block Signalling Chapter 20 (PDF)

    Description

    Explore the fundamentals of Automatic Block Signalling systems, which control train movement through stop signals. This quiz covers how these signals operate automatically as trains enter and pass through designated sections, ensuring safety and efficiency in rail transport.

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