Limit of authority
The clearing of a signal gives authority to enter the block for which the signal has been cleared.
Running signals
A running signal authorises a through-movement between that signal and the next running signal.
Other than for shunting movements, Signallers must not clear a running signal if the block ahead is occupied.
A Signaller may use a running signal to authorise a shunting movement if:
- there is no shunting signal available
- the Driver or Track Vehicle Operator has been told.
Shunting signals
A shunting signal authorises a movement at restricted speed past that signal.
If possible, Signallers must use shunting signals to authorise shunting movements.
Shunting signals can be cleared if the line beyond the signal is occupied. Drivers and Track Vehicle Operators must proceed as if the line is already occupied.
Unless the Signaller instructs that a movement is to proceed for a shorter distance, a PROCEED indication by a shunting signal is an authority to proceed up to and not beyond the first of the following limits reached:
- SHUNT LIMIT sign
- STOP sign
- indicator showing that points are not set, catch points are open, or a derail device is set on the rail
- set of non-interlocked points
- signal for the direction of travel.
A Signaller may use a subsidiary shunting signal to authorise rail traffic to pass a home signal, if the running signal:
- fails to clear, or
- cannot be cleared because rail traffic occupies the line beyond the signal.
A Signaller must not use a subsidiary shunting signal as the sole authority for rail traffic to pass a starting or home/starting signal for a through movement. The movement must be made in accordance with NSG 608 Passing signals at STOP.
If a subsidiary shunting signal is used to authorise rail traffic to pass a running signal at STOP, the Driver or Track Vehicle Operator must proceed at restricted speed.