Automatic Block Signalling - General

A system that automatically controls train movement using stop signals triggered by train passage.

A color-light signal that automatically regulates train entry into a signalling section, controlled by train passage.

A portion of a railway line between two adjacent crossing stations, controlled by signals to regulate train entry.

The minimum distance, beyond the next signal, necessary for the line to be clear before a signal can turn off.

Signal spacing must meet operational needs, providing adequate braking distance but not causing issues during failures.

The distance a train needs to stop applying emergency brakes.

The space between signaling aspects (e.g., caution and stop) in three or four aspect signaling should be enough that the trains can stop if emergency braking is needed.

Minimum distance (120m for automatic, 180m for manual/semi-automatic stop signals) beyond the next signal for automatic signals to turn off.

A fixed signal needing manual actuation to turn off. It automatically turns on when a section is occupied but requires a manual action to turn off when the section is clear.

A fixed signal controlled manually and automatically by track circuits. It can operate as either an automatic or manual stop signal.

An automatic block system operating on a single track, where line clearance must be confirmed before traffic direction can be determined.

Guidelines for line clearance and traffic direction establishment in single-line operations

A railway signaling system where trains are automatically controlled on a single track using track circuits, axle counters, and stop signals.

A condition where the track section ahead is clear of trains, allowing for the establishment of the direction of traffic for subsequent trains.

The designated flow of trains on a single line, either in one direction or the other, determined by signal conditions.

A signal that automatically controls train entry into a block section and remains 'off' only when the track ahead is clear up to the next signal.

The minimum distance, beyond the next Stop signal, required for the line to be clear before the current signal can turn off.

Setting the direction of traffic flow between two crossing stations on a single line, ensuring conflicting signals are prevented.

The section of track beyond a signal where the signal remains off even if a train is in the next block section, providing a safety margin.

A system used to set the direction of traffic flow, preventing conflicting signal activations.

A mechanism preventing unauthorized access or operation until a specific condition is met.

A system using electric current to detect train presence on a section, enabling automatic signal control.

A system using sensors to count train axles, providing information for controlling signals.

A separate track circuit for the overlap area, ensuring safe braking space before the signal changes.

Having backup systems to maintain signal integrity even if one fails.

Using different technologies or methods for axle counting to improve reliability.

A display at each station showing whether the block section is occupied or clear.

Circuits designed to ensure safety even if a component fails. They are continuously energized, so any break in the circuit will trigger a safety response, preventing an unsafe situation.

A safety measure where external circuits have two independent switches, both needing to be open to disconnect the circuit. This prevents accidental activation or disconnection.

A signal aspect that indicates a lower speed or a stop, providing a more restrictive condition than the current aspect.

A signal that can operate either automatically or manually, depending on the specific traffic conditions.

An illuminated marker on a signal indicating that the signal is operating in automatic mode.

An illuminated marker indicating that the signal is operating in automatic mode, even if the level crossing gate is open or failed, allowing trains to proceed with caution.

Points refer to the switching mechanism for the railway tracks, and back-locking ensures that the points remain locked in the correct position, preventing accidental switching. The 'A' Marker illumination proves this.

Automatic signalling information, such as signal aspects, track status, axle counter readings, and gate information are available and visible at the station for operator awareness.

A special type of signal that operates both automatically and manually, primarily used during adverse conditions like fog or bad weather.

A modified semi-automatic stop signal located in the middle section between two stations. It ensures safe train operation by limiting the number of trains within the section.

Indicates that the modified semi-automatic signal is in operation and should be treated as a manual signal rather than an automatic signal.

The visual display on a signal, indicating the allowed train movement.

A gate signal, typically used at level crossings, can be converted to a mid-section modified semi-automatic signal for enhanced safety and control.

The mid-section modified semi-automatic signal can operate in two modes: normal automatic mode and modified semi-automatic mode.

The mid-section modified semi-automatic signal is painted with alternating blue and white stripes to distinguish it from other signals.

The station masters at both ends of the section are informed about the operational mode (normal automatic or modified semi-automatic) of the mid-section modified semi-automatic signal.