Block Instruments Safety Standards

A system for increasing section capacity on railway tracks by dividing a long block section into two parts (rear and advance) with signaling equipment placed at the point of near bifurcation.

The portion of the track section starting from the rear station's Local Signal Station (LSS) and extending to the IBS, including a 400-meter overlap.

The track section starting at the IBS and continuing to the home signal of the advance station, including block overlap.

The strength of electrical signals at specific points on electronic railway equipment, maintained within acceptable limits.

Regular maintenance for embedded block working systems, following schedules provided by the Original Equipment Manufacturer (OEM).

The location where track signals and communications are managed for a specific section of railway.

System of control that manages railway signals and points to permit safe switching and train movements.

Methods used to monitor train movement and track occupancy in railway sections.

A communication device at the IBS location for communication with the station in the rear.

If a lost token isn't found within six months, it's replaced with the next higher number in the series.

Technicians transfer tokens between instruments to ensure balance in a section.

A form used by technicians to record token transfers and verify transfers with staff.

When the token balance in a station's record drops to six tokens, the station master warns the technician(signal).

Instruments must be in the "Line Closed" position when extracting/replenishing tokens.

A register where token balancing operations are documented.

Essential signals that must be used, even if telephones are available, as part of safe train operations.

Technicians verify token extraction & replenishment with station masters and update the relevant records.

Verify token movements and authorize transfers; notify Technicians (Signal) when token balance falls below 6.

Damaged token pouches are prohibited for use and must be repaired by Traffic Department.

The process of taking tokens from a station, recording details, and signing off.

Block instruments must be mounted horizontally (level) to prevent tokens from getting into a wrong race or tilting in ball and tablet token instruments.

Refers to the specific location where tokens are kept or taken from, most likely a railway station.

Correct polarities must be connected to the instrument ends for proper operation.

The person in charge of a railway station, overseeing token management and train operations.

Ensure all mechanical parts in the instrument move freely without friction or jamming.

A unique identifier for each token, used for tracking purposes.

The commutator within the token instrument should only change state when the token moves through the races or slides along the rail.

Check the insulation of electrical components and wiring for proper resistance against leakage from the instrument body and grounding.

The date and time when tokens are taken, checked, or replenished at a station.

Single line tokenless instruments must be mounted level with easy maintenance access and space.

The signature of the person handling the tokens to confirm the transaction.

The overall count of tokens at a particular station or point.

Before installation, inspect the instrument for damage, corrosion, loose or missing fasteners, split panel issues and ensure working condition of relays and counters.

Measure insulation resistance between each insulated circuit and grounding.

The minimum insulation resistance between every insulated circuit and earth must be at least 10 megaohms.

Block release is activated by the sequential operation of two track circuits.

The 'Last Stop Signal' at the sending station can't be switched off until the receiving station is set to 'Train Coming From' and the sending station is set to 'Train Going To'.

A schedule for maintaining block instruments (single line, double line, push button).

Maintenance schedule for double line block instruments (lock and block).

Maintenance schedule for tokenless block instruments (single line, push button).

Maintenance schedule for analog block axle counter systems (BPAC).

Maintenance schedule for tokenless block instruments (single line, handle type).

Maintenance schedule for Universal Fail-Safe Block Interface (UFSBI).

Drawing showing the layout of the Instrument Block hut.

Drawings of signalling systems with specific devices.

Drawing depicting the circuit filtering unit.

Drawings of protective devices for AC electrified areas in token instruments.

Drawing illustrating double-line block operation with AC protection.

The casing of the single line ball token/tablet instruments is painted grey enamel

The casing is painted grey enamel.

The wooden elements of double line instruments are painted with spirit polish.

The metal casings of double line instruments are painted green enamel.

Defined areas of railway track for signaling and control, outlined by specific points along tracks.

A track section encompassing multiple track sections for higher-level control and reset.

A system using multiple methods for detecting the presence of a train to improve reliability.

A section of track managed by Intermediate Block Signaling, normally with three sections in each direction (AS, IB, BPAC).

Instances of Multi-Sensor Axle Counters (MSDAC) malfunctioning, often caused by loaded rakes or recurring wheel movement over coils.

Locks for train movements. Must be free-moving, approximately 1 mm above the rack, and have square edges.

Parts susceptible to wear should be replaced during overhauling.

A part whose shape, square end, and 9.5mm width must be checked.

Tablet holding arm's release lever must operate properly, allowing tablet release only after complete rotation and handle release in the "Train Going To" position.

Notches of the token rack must have the correct shape and square edges.

Tests from para 18.5.2 should be executed.

The locking assembly needs replacement during every overhaul.

Ensure proper functioning of axle counter track equipment and UFSBI by maintaining specific parameters.

Both instruments in a section must be returned to normal to initiate another train movement to/from the section.

Mechanisms to receive and grant clearance to move a train must be used one at a time.

The instrument indicating the direction the train is heading must be restored to "Line Closed" after arrival.

One token can only be extracted when the instrument is set to "Train Going To".

Tokens must be placed in the specific block section instrument, and won't be able to transfer to adjacent sections.

Each token contains the station names and serial number for identification.

Single-line tokenless systems have fixed indicators to show "Train on Line" at both ends of the section.

Single-line tokenless instruments use coded impulses to avoid interference from unwanted electrical signals.

A schedule for maintaining block instruments (single line, double line, push button).

Maintenance schedule for double line block instruments (lock and block).

Maintenance schedule for tokenless block instruments (single line, push button).

Maintenance schedule for analog block axle counter systems (BPAC).

Maintenance schedule for tokenless block instruments (single line, handle type).

Maintenance schedule for Universal Fail-Safe Block Interface (UFSBI).

Painted grey enamel.

Grey enamel.

Spirit polished.

Green enamel.

The maximum voltage a PR relay can handle without failing safely; in this case, it's 10V.

Devices used to prevent signal interference or distortion in block instruments exceeding the voltage limit of the PR relay.

Block instruments that use a handle for controlling the block signals.

A signal transmitted using specific frequencies to represent information.

A type of block instrument that uses a single line, a push button, and no physical token.

The maximum distance a single-line, push-button token system can reliably operate (1.5 km).

A type of interference that affects the reliability of block instruments using DC encoding.

Each instrument requires its own independent ground connection for safety reasons, reducing interference between systems.

Earth ground connections must be buried at a minimum depth of 1.5 meters.

Grounding resistance of such systems should be capped to 10 ohms to provide effective continuity.

Systems that use the earth for completing electrical circuits.

Electrical systems that use metal wires or conductors for completing circuits, instead of using the earth.

Tokens must be installed so that they cannot be placed in a different instrument at the same station.

Overcarried tokens should not be placed in the instruments of subsequent stations.

Standard token configuration types used in consecutive block sections.

Token configurations used at station junctions, or when new crossings are introduced.

Relay signals for track sections, collected at the track section's entry point (station or IB location).

Input/Output Exchange Boxes used to exchange signaling data between locations.

Signaling mode exchanging 3 vital I/Os between locations using IO-EXBs.

Signaling mode exchanging 12 non-vital I/Os between locations using IO-EXBs.

A specific configuration for IBS-NW (DN) with quad/single mode I/O.

A specific input/output exchange box for signaling.

North-West Instrument Block Signal (Downward direction).

A particular input in a signaling system configuration.

A particular output in a signaling system configuration.

A railway signaling system that increases track capacity by dividing a block section into two parts, allowing simultaneous train movement in both directions.

Intermediate Block Signaling using copper cables for communication between sections.

Intermediate Block Signaling using a combination of quadrupled connection to copper cables for communication between sections.

A device used to monitor wheel movements over track sensors

A device that detects train movements using multiple sensors for improved track safety (distributed architecture).

Single section digital axle counters problems arising from not having backups.

Utilizing multiple methods to detect a train's presence for increased reliability.

Specific points along railway tracks marking segments for signaling and control.

Intermediate block section including three sections – Advance section, Intermediate Block, and Block Position and Axle Counters (BPAC).