Railway Control Systems
The operational railway is managed through a hierarchy of interconnected systems. From physical train detection on the track to high-level traffic management in control centres.
System Connection Map
Select a stage in the control flow below to understand how information moves from the physical track up to the control centre and back out to influence train movement.
1. Train Detection (Track Level)
The system must first know where trains are. This is done using Track Circuits (which use the train's axles to short an electrical circuit) or Axle Counters (which count wheels in and out of a section). This data confirms if a block section is occupied or clear.
2. Interlocking (Logic Level)
The detection data feeds into the interlocking system. If the signaller requests a route, the interlocking checks the detection data to ensure the track is clear, sets the points, locks them, and ensures no conflicting routes are set. It acts as the safety gatekeeper.
3. Control Centre (Management Level)
Signallers and traffic managers work in control centres, monitoring vast sections of the network via digital displays. They make routing decisions, manage delays, interface with station staff, and request routes from the interlocking systems based on the timetable.
4. Signal / Cab UI (Interface Level)
Once the interlocking confirms a route is safe and locked, it outputs a command. This either clears a physical lineside signal to green/yellow, or transmits a digital Movement Authority directly to a screen inside the train driver's cab (in ETCS/CBTC systems).
5. Train Movement (Execution Level)
The driver interprets the signal or cab display and controls the traction and braking of the train accordingly. As the train moves, it triggers the next set of train detection hardware, starting the cycle again.