Description
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Running signal operation
Controlled signals
Controlled signals, other than distant signals, can be set and kept at STOP.
Controlled signals are operated by:
- signalling equipment controlled by Signallers, or
- a combination of track‑circuits, or axle counters, and signalling equipment controlled by Signallers.
Controlled signals can display a PROCEED indication only if:
- points in the route are in the correct position
- there are no conflicting routes set
- in Rail Vehicle Detection territory, the block ahead is unoccupied.
Controlled signals at attended locations are absolute signals.
| Type | Controlled operation status identified by |
|---|---|
| Double light colour light signal | Vertical lights. If an A sign or illuminated A light is on or near the signal, the operation mode is automatic. |
| Single light colour light signal | Marker light vertically below main signal lights. If an A sign or illuminated A light is on or near the signal, the operation mode is automatic. |
| Lower quadrant semaphore signal | Lower quadrant signals are controlled signals. |
Automatic signals
Automatic signals are controlled exclusively by the operation of track-circuits.
An automatic signal displays a PROCEED indication only if the line is unoccupied as far as the overlap point beyond the next signal.
Automatic signals are permissive signals. They can become absolute signals if they:
- are so designated by an instruction sign, or
- are interlocked with trackside monitoring equipment that sets them at STOP, or
- can be switched between automatic and controlled operation.
| Type | Automatic operation status identified by |
|---|---|
| Double light colour light signal | Staggered lights, or vertical lights with an A sign or illuminated A light on or near the signal. |
| Single light colour light signal | Marker light staggered below main signal lights; marker light vertically below main signal lights with an A sign or illuminated A light on or near the signal. |
| Lower quadrant semaphore signal | There are no lower quadrant automatic signals. |
A lights and A signs
In Rail Vehicle Detection territory only, some signals may be fitted with an A light or an A sign.
An A light can be fitted:
- on the post below a signal, or
- on or near a tunnel‑type signal.
If an A light is not lit, the signal is a controlled signal.
If the A light is lit, or the signal has an A sign on or near the signal, the signal:
- operates automatically
- is designated as an automatic signal.
