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Section 9: Signal Post Signs and Signals for Degraded Working

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From 1996, signal post telephones were being removed, or not provided, where they could not be positioned in a place of safety. All communication between driver and signalman at those signals would be by the National Radio Network (NRN) (see Section 19). Signs were provided at the signals concerned, quoting the appropriate extension number for the signal box [9.46]. In some cases, two extension numbers are given [9.47]. Telephone number signs are also provided at those signals where the signal post telephone is retained but normally barred from use.

[9.46] Telephone Number Sign. Click Here for Photo
Area: All Areas   Usage: High   Status: Current
[9.47] Telephone Number Sign.
Area: All Areas   Usage: Medium   Status: Current

In the Scotland Zone, the telephone number sign was combined with the appropriate form of diamond sign [9.48 & 9.49]. The combined signs have subsequently also been used on Network Rail's London North Eastern Territory.

[9.48] Combined Diamond Sign and Telephone Number Sign.
Area:  Predominately Scotland Zone   Usage: High   Status: Obsolescent
[9.49] Combined Diamond Sign with "X" and Telephone Number Sign.
Area:  Predominately Scotland Zone   Usage: High   Status: Obsolescent

In 1996, new identification plates were introduced for use on SPAD indicators and colour light distant signals. The SPAD indicator plate has a blue background [9.50] matching the new style of indicator introduced at the same time (see [8.28 & 8.29]). The 'delta' plate, which bears a solid white triangle [9.51], is intended for use on all colour light signals that are not capable of displaying a red aspect (other than a 'non-approachable' red aspect). It positively identifies the signal as a distant signal, which may be passed if it is found to be unlit. This sign has, however, erroneously appeared on several semaphore distant signals, reflectorised distant boards and even banner repeaters.

[9.50] Identification Plate for SPAD Indicator. Click Here for Photo
Area: All Areas   Usage: Medium   Status: Obsolescent
[9.51] Colour Light Distant Signal Identification Plate. Click Here for Photo
Area: All Areas   Usage: High   Status: Current

When a colour light signal is fitted with a blue and white striped surround (see [8.20]), its identification plate may, by exception, be replaced with one that has a blue background [9.52]. One signal so treated, L120 at London Bridge, carried a blue and white striped surround and a blue identification plate from 1998 until 2012, when both were removed.

[9.52] Signal Identification Plate with Blue Background.
Area: Various   Usage: Low   Status: Obsolescent

On the Southern Zone, a sign may be provided at a signal to indicate that drivers should alight from the right-hand side of the train to use the signal post telephone. The sign depicts a black telephone handset merged with the image of a driver climbing down from his cab, below which is a blue arrow pointing right [9.53].

A standard sign with black and white diagonal stripes and an arrow [9.54] was introduced for use where the location of the signal post telephone (e.g. on the opposite side of the line) might not be obvious to a driver standing at the signal. This sign is fixed on or near the signal.

[9.53] Signal Post Telephone Location Sign.
Area: Southern Zone   Usage: Medium   Status: Obsolescent
[9.54] Signal Post Telephone Location Sign (e.g. S.P.T. on right-hand side of line).
Area: All Areas   Usage: Medium   Status: Current

In 2000, under a local initiative, a trial was carried out whereby the identification plates on two signals at Norwich were replaced. The new identification plates quoted the Ordnance Survey national grid reference at the bottom, in small characters [9.55]. This allows accurate location information to be given to emergency services in the event of an incident. Similar plates were subsequently fitted to other signals in the East Anglia Zone.

[9.55] Signal Identification Plate showing National Grid Reference.
Area: East Anglia Zone   Usage: Medium   Status: Uncertain

From 2002, use of the 'semi-automatic' signal (see [9.26]) for new works was discontinued. In future, all colour light stop signals (other than Intermediate Block Home signals (see [9.32]) ) would be designated either 'passable' or 'non-passable'. This resembles the practice of the French Railways (SNCF), where signals are designated either Franchissable or Non-franchissable. The plate formerly indicating that a signal was 'automatic' (see [9.25]) was used to denote that a signal is 'passable'.

Block markers on lines with TVM cab signalling (see [2.126]) are designated either as 'Absolute Stop' markers or 'Stop & Proceed' markers. An absolute stop marker is equivalent to a non-passable signal, and a stop & proceed marker is equivalent to a passable signal. The original proposal had been to distinguish one type of marker from the other in the same manner as signals, meaning that a stop & proceed marker would have carried the same identifying plate as was fitted to a passable signal (see [9.25]). However, when the first block markers were brought into use on the CTRL in 2003, a different system was adopted, which more closely reflected practice on the French high speed lines. An absolute stop marker carries a plate lettered "N" (for 'non-passable') [9.56], and a stop & proceed marker carries a plate lettered "P" (for 'passable') [9.57]. The equivalent signs in France are similar but bear the letters "Nf" (for 'non-franchissable') or "F" (for 'franchissable').

[9.56] "N" Plate. Click Here for Photo
Area: CTRL   Usage: Medium   Status: Current
[9.57] "P" Plate.
Area: CTRL   Usage: High   Status: Current

On lines with TVM signalling, absolute stop markers (see [2.126]) and shunt markers (see [3.89]) are provided with an auxiliary signal, which is normally extinguished. When 'opened', an auxiliary signal displays two flashing white lights at 45° [9.58], authorising the driver to proceed on sight (e.g. during a failure or for admission into an engineering possession). A similar aspect, called a 'Proceed on Sight Authority' (PoSA), has also been introduced in some areas with conventional colour light signals, for use during certain failure conditions. The first line to be equipped with PoSAs was the East London Line, in 2010.

[9.58] Auxiliary Signal ('opened') / PoSA ('off').
Area: All Areas   Usage: Medium   Status: Current

A non-standard sign with a yellow background has been fitted to some signals in the Southern Region to show the location of the signal post telephone [9.59]. This sign is properly intended for use at level crossings, to direct road users to the location of the emergency telephone.

[9.59] Signal Post Telephone Location Sign.
Area: Southern Region   Usage: Low   Status: Obsolescent

Many of the signal identification plates fitted to main signals in mechanically signalled parts of the Worcester area have black characters on a white background, the reverse of the usual standard. Even the 'delta' plates for distant signals bear a solid black triangle on a white background [9.60].

[9.60] Distant Signal Identification Plate with White Background. Click Here for Photo
Area: Worcester area   Usage: Medium   Status: Obsolescent

In 2010, the rules were changed such that drivers could no longer pass an automatic ('passable') or semi-automatic signal at 'danger' on their own authority when unable to contact the signalman. It is still permitted to pass an Intermediate Block Home signal when these circumstances apply. On lines with ERTMS cab signalling, it had originally been envisaged that block markers (see [2.127]) would either be designated as 'passable' or 'non-passable'. In common with a 'stop & proceed' marker on a TVM-signalled line, a passable ERTMS block marker would be fitted with a "P" plate (see [9.57]). The "N" plate (see [9.56]) would not be used on ERTMS lines, however, and instead it would be the absence of a "P" plate that identified a block marker as non-passable. In the event, there were no passable ERTMS block markers in existence when, in 2012, it was decided that all block markers on ERTMS lines would in future be treated as non-passable. This brought the instructions for passing an ERTMS block marker without a movement authority into line with the previously amended instructions for passing an automatic or semi-automatic signal at 'danger'.


In 2012, a distinctive form of identification plate was introduced for use on three-state banner repeaters (see [7.54]) as an aid to route learning. The symbol on the plate resembles a banner repeater showing an imaginary vertical indication [9.61].

[9.61] Three-State Banner Repeater Identification Plate. Click Here for Photo
Area: All Areas   Usage: Medium   Status: Current