Signalling Essentials Chapter Overview

Distant signals placed at least 1 kilometer behind the first stop signal in a single distant territory.

If emergency braking distance exceeds 1 kilometer, a second distant signal is placed at least 2 kilometers behind the first stop signal and an inner distant signal at least 1 kilometer behind the first stop signal in a double distant territory.

The home signal is placed behind any connections on the line in question, at least 180 meters from the obstruction point after a line clearance signal to the rear station has been issued.

Indicates a complete stop

Indicates caution or potential danger

Indicates attention and a specific signal action (possibly not an immediate stop but specific action)

Indicates permission to proceed

Signals to the loco pilot that the train should stop before an obstruction.

Displays no light in the 'ON' position, and has a miniature yellow light when 'OFF'.

A white enamelled disc with a black 'C' letter.

Placed below a Stop Signal, or in special cases, below other stop signals (except the last).

Cannot work simultaneously with the Stop signal above or any shunt signal below.

Locks and detects all points in the route, including isolation points, (except those overlapping).

Requires all level crossing gates to be closed and locked during operation

Station masters control the reception and dispatch of trains when operating calling-on signals.

Track circuits at a suitable distance with time delay circuits, ensuring the 'OFF' position when the train is stationary.

No time delay is needed for dispatch signals to be taken off.

Shunt movements (shunting) are primarily controlled by Shunt Signals.

The space between signals.

Typically on the left side of the track.

Signals are combined when the distance between them is too small for separate warning boards.

Used to alert train drivers about signaling changes or block systems used.

Used when approaching a station/area without Stop Signals.

Signifies you enter a section using Token Block system.

Signifies the entrance to an area with an absolute block system where a train is always expected or is always authorized to pass.

Signifies the entrance to an area with an automatic block system that controls train movement without full human intervention.

A board used for shunting operations at Class 'B' stations in single-line sections.

Route settings in the installation use an entry/exit principle.

Signal clearing is done by individual buttons or switches.

Control panel/VDU system to prevent unauthorized operation by using a key.

Panel/VDU feature for releasing routes in emergencies.

Required a two-step process for unintended operation precautions.

Security measures for covers of control panels, and block instruments to prevent unauthorized access.

Provide information about Point, Route, Signal, Track Circuit, Power Supply and other relevant parameters/status.

Must display the yard layout in well-proportioned dimensions, with clear functions.

Multiple Control Terminals are essential to ensure system reliability.

Signal, point, and control operations (gates, cranks, sidings, slots) are managed through designated drop-down menus or approved methods.

Electronic interlocking systems must provide indications (TGT, TCF, LC) for block signaling.

Control terminals (e.g., VDUs) have the same indication requirements as control panels.

Yard signaling and interlocking follow approved plans, control tables, detailed wiring diagrams, and relay analysis/rack arrangements.

Outdoor components (LC Gates, signalling cables, train detection, signals, etc.) are installed, tested, and maintained according to specific chapters of the Standard Equipment Manual (SEM).

Signalling power systems follow requirements outlined in a dedicated SEM chapter. This includes considering RE (Railway Electrified) areas and 25 KV AC systems.

Block instruments are installed, tested, and commissioned according to specifications in the SEM.

Electrical and electronic signaling equipment must be protected from lightning and surge damage by appropriate installations.

Grounding procedure for outdoor signalling equipment, per Chapter 19, Section 11.

Air conditioning, fire detection/suppression systems in relay rooms should adhere to Para 21.3.4.

Tests performed before commissioning of outdoor and electronic interlocking systems.

Process for starting up outdoor signalling, includes SIT checks per Chapter 19, Para 19.8.8.

Starting up electronic interlocking systems, including SIT per Chapter 21 and Chapter 19, Para 19.8.8.

Found in Appendix II; providing guidance on installations, adaptable to site needs.

Appendix I provides schedules for signalling equipment maintenance, supplementable with industry best practices.

Standardized features required at stations based on interlocking standards, listed in Table-3.

Placed at least 1 kilometer behind the first stop signal in a single distant territory.

If emergency braking distance exceeds 1 kilometer, then a second distant signal is placed at least 2 kilometers behind the first stop signal, with an inner distant signal at least 1 kilometer behind the first stop signal in a double distant territory.

Placed behind any connections on the line, at least 180 meters from the obstruction point, after a line clearance signal to the rear station has been issued.

Indicates a complete stop.

Indicates caution or potential danger.

Indicates attention and a specific signal action (possibly not an immediate stop).

Indicates permission to proceed.

Used at points not connected to signals to show point position.

Displays white target by day, white light by night.

Displays disc edge by day, green light by night.

Show position of trap points/derailing switches.

Displays red target by day, red light by night.

Displays disc edge by day, green light by night.

Allows uninterrupted shunting movements.

In unusual situations, grade crossings may be allowed with special instructions, preventing trains from stopping on inclines or vehicles rolling away from stations, or when trains arrive from different directions simultaneously.

Points used to divert trains onto a short dead-end track, for trapping or derailing, and positioned on main or through lines.

Siding points that branch off running tracks in the opposite direction, requiring gauge tie plates, independent lock switches, key or device control interacting with block systems.

Facing points require a gauge tie plate, facing point lock for each switch, and key or device-controlled bolting, interlocked with the block system.

A specified speed limit is enforced for trains crossing facing points in one direction, with visible markers and indicators.

Siding points located outside of a station, with specific facing point characteristics, that follow regulated procedures.

The trap switch should be positioned with its heel behind the fouling mark, preferably on the straight, and away from the line being protected.

Method A for isolation uses a clear line ahead for the distance prescribed by Rule 3.40.

For short dead-end sidings, points are set for crossover, ensuring the adequate distance of Rule 3.40. If extending for stabling, a trap at minimum 180 meters from signal or points is needed.

Method C uses a trap, and trains can only be allowed if the trap is closed to prevent derailment.

A sand hump of approved design replaces the distance requirement (Rule 3.40(4)) if other isolation methods aren't practical.

Catch siding points remain set and locked until the Home Signal is turned OFF.

Station Master must manually verify complete train arrival/departure even with audible warnings, ensuring all parts of the train are accounted for.

Station Master keeps an emergency key for operating points when block instruments fail or a train needs to enter a section when another already exists.

Main and subsidiary signals cannot be turned off unless all points in the route (including overlaps and isolations), interlocked level crossings are closed, and relevant tracks are clear.

After a signal is turned 'OFF', you cannot move points, unlock the route, or open interlocked gates until the signal is turned 'ON'.

It is not permitted to turn off two signals at the same time, as this could lead to conflicting train movements.

The route, including overlap and isolation points, is locked by the signal and is released when a train passes or via emergency release with a delay.

Signal, point, and control operations (like gates, cranks, sidings, slots), are managed via dropdown menus or approved methods.

Electronic interlocking systems display indications (TGT, TCF, LC) required for block working.

Provide information on Points, Routes, Signals, Track Circuits, Power Supply, and statuses of other systems.

Outdoor components (gates, cables, detection, signals) are installed, tested, and maintained per specific SEM chapters.

Signalling power systems follow guidelines in a specific SEM chapter, considering railway electrified areas and 25 KV AC systems.

Block instruments are installed, tested, and maintained per SEM guidelines.

Electrical/electronic signalling equipment needs protection from lightning and surges, according to a chapter in SEM.

Yard signalling and interlocking arrangements follow approved plans, control tables, wiring diagrams, and relay analysis/rack arrangements.

Control terminals (like VDUs) have same indication requirements as control panels in signalling layouts.