NSG 606 Responding to signals and signs (2025)

Purpose

To prescribe the rules for responding to signal indications and signs in the Network.

Principle

Fixed signals are devices near lines to:

separate and regulate rail traffic
tell Drivers, Track Vehicle Operators and other Qualified Workers about the status of the line ahead
show which route is set.

There might be permanent or temporary signs instead of fixed signals.

Drivers, Track Vehicle Operators and Qualified Workers directing shunting and propelling movements must obey the indications and instructions displayed by signals, indicators and signs.

Changing signal indications

If rail traffic is closely approaching a signal, the Signaller must not change the indication of the signal to a more restrictive aspect unless there is a Condition Affecting the Network (CAN).

If rail traffic is standing at a signal, the Signaller must not change the indication of the signal to a more restrictive aspect unless:

there is a CAN, or
the route needs to be altered, and it is safe to do so.

If possible, the Signaller must arrange for the Driver or Track Vehicle Operator to be told about the change of the signal aspect.

Signals must be tested in accordance with NSG 616 Precautions during signalling equipment testing.

Route and locality knowledge

Qualified Workers who observe, operate or maintain fixed signals must know the locations and purposes of signals in their areas of work.

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.

Warning

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:

SHUNTLIMIT sign
STOP sign
indicator showing that points are not set, catch points are open, or a derail device is set on the rail
setofnon-interlockedpoints
signalforthedirection 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.

Signal indications

STOP

Rail traffic must stop before a signal at STOP.

Drivers or Track Vehicle Operators must keep the signal indication clearly in view.

If both a co-acting signal and the associated primary signal display STOP, rail traffic may pass the co-acting signal but must stop at the associated primary signal.

Signals may be passed at STOP only in accordance with NSG 608 Passing signals at STOP.

PROCEED

A PROCEED indication shows that:

interlocked points protected by the signal are set in the correct position for the movement
no conflicting route has been set.

Other than for shunting movements, a PROCEED indication by a running signal shows that the block is unoccupied as far as the next running signal.

A PROCEED indication by a shunting signal does not indicate that the block ahead is unoccupied.

LOW SPEED

Low speed signals are small in-line green lights:

in or below the bottom of the lower case of double colour light signals, or
below the main lamp case of single colour light signals.

Low speed aspects indicate that the line to the next signal is unoccupied. They authorise rail traffic to proceed, but to expect:

CLOSE UP

CLOSEUP signals indicate that the line to the next signal is unoccupied. They authorise rail traffic to proceed, but to expect the next signal to be at STOP.

Note

The line may be occupied immediately beyond the next signal.

Irregular signal indications

A fixed signal indication must be treated as STOP if:

it is an illegal signal indication, or
there is no indication, or
there is no indication other than the route indicator, or
it is not understood.

Illegal signal indications

A signal indication is illegal if it is not consistent with:

the aspects and indications used in the Network
the indications of adjoining signals and the known condition of the line
what is known about occupancy of the line.

Qualified Workers must report illegal signal indications to the Signaller responsible for the portion of track.

The Signaller must:

if the affected signal is a controlled signal, set the affected signal to STOP with blocking facilities applied
give Drivers and Track Vehicle Operators a CAN warning about affected automatic signals
tell the Network Controller
tell a Signals Maintenance Representative.

Affected signals must not be used to provide PROCEED indications before they have been certified back into use.

Partial indications

Colour light running signals

If a light in a colour light running signal is not visible, Drivers or Track Vehicle Operators must act as if the aspect is the most restrictive combination for the remaining displayed lights.

Colour light signals with route indicators

If a colour light signal shows a PROCEED indication without the route indicator being visible, Drivers or Track Vehicle Operators must obey the PROCEED indication.

Semaphore signals

If, in darkness, no lights are displayed by a semaphore signal, Drivers or Track Vehicle Operators must obey the indication displayed by the signal arm.

Signals not in use

A signal that is not in use must:

have a large white “X” hung over the signal, or
if next to a functioning signal, have its head covered or turned away from the line.

Drivers or Track Vehicle Operators must ignore indications of signals marked as not in use.

Signal placement

Signals for a unidirectional line are preferably to the left of the line in the direction of travel. If this is not possible, they may be placed:

above the line, or
to the right of the line.

Signals for a double line bidirectional line are usually:

for travel in the usual running direction, to the left of the line
for travel opposite to the usual running direction, to the right of the line.

If a signal is placed to the right of the line, a left pointing arrow may be used to indicate the line to which the signal applies.

Running signal indications

The legal PROCEED and STOP indications shown by colour light and semaphore signals in the Network are, from least restrictive (highest) aspect to most restrictive (lowest) aspect:

Note

In the figures, lunar white lights are shown in blue; pulsating lights are shown with radial lines .