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Section 18: Signs in Electrified Areas

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Mainline railway electrification in Great Britain has its origins in the early 20th century. The first electrification schemes supplied DC traction energy to trains, at a variety of different voltages, along either a third rail or overhead lines. In 1956, British Railways adopted the French 25 kV AC overhead method of electrification as standard for future work, apart from extensions to other existing systems. A lower voltage of 6.25 kV was originally employed in built-up suburban areas, which was later converted to the standard 25 kV.


The North Eastern Railway had electrified some railways around Tyneside in 1904. Drivers of electric trains were required to shut off the power after reaching full speed and allow the train to coast as much as possible. A diamond shaped board with a red border [18.1] was installed at the point where the power should normally be switched off, under normal conditions with a fully loaded four-coach train. A diamond shaped board with a green border [18.2] marked the point where the power could be switched on again.

[18.1] 'Switch Power Off' Board.
Area: NER   Usage: Unknown   Status: Historical
[18.2] 'Switch Power On' Board.
Area: NER   Usage: Unknown   Status: Historical

On the DC electrified lines of the LMS, lineside signs with the words "section gap" [18.3] marked the locations where the live rail was gapped. Should there be no power in the section ahead, an indicator reading "track dead" [18.4] became illuminated on the post of the protecting signal, which would remain at 'danger'. The driver had to stop and telephone the signalman if a "track dead" indicator was lit.

[18.3] "Section Gap" Board.
Area: LMS   Usage: Medium   Status: Current
[18.4] "Track Dead" Indicator.
Area: LMS   Usage: Medium   Status: Historical

On lines electrified by the third rail DC system, flood indicators may be installed at certain areas susceptible to flooding. On the Watford 'New' Line, indicators were provided on the approaches to Harlesden Long Bridge. In the event of flood water reaching the top of the running rails, the indicators were illuminated, each displaying the word "flood" [18.5]. The protecting signals were automatically placed or maintained at 'danger'.

[18.5] Flood Indicator.
Area: LMS   Usage: Low   Status: Historical

There was a requirement on electrified railways for telephones to be provided at the lineside at no more than 500 metre intervals. When the Manchester - Sheffield - Wath line was electrified in 1954, electrification telephones were identified by a sign similar to the signal post telephone sign (see [9.14]) but with a red band at the bottom [18.6]. This line closed in 1981. The standard sign for an electrification telephone shows a telephone handset in red outline and the word "electrification" [18.7]. The provision of NRN (see Section 19) ended the requirement for dedicated electrification telephones on AC overhead electrified lines, apart from inside tunnels.

[18.6] Electrification Telephone.
Area: M-S-W line   Usage: Medium   Status: Historical
[18.7] Electrification Telephone.
Area: All Areas   Usage: High   Status: Current

For staff safety reasons, some goods yards in the Southern Region were provided with overhead wires in the 1950s. This enabled DC locomotives fitted with pantographs to shunt in these yards without the need for a third rail. At the point where the pantograph was to be raised or lowered, a board was provided bearing an "R" on one side ('raise pantograph') [18.8] and an "L" on the other side ('lower pantograph') [18.9].

[18.8] 'Raise Pantograph' Sign.
Area: Southern Region   Usage: Low   Status: Historical
[18.9] 'Lower Pantograph' Sign.
Area: Southern Region   Usage: Low   Status: Historical

Lineside warning signs are erected on the approach to overhead electrified lines. The original style of warning sign had a 'flash' symbol and an upward pointing arrow [18.10]. The rear of the sign may be painted with green and white diagonal stripes [18.11].

[18.10] Warning sign at entrance to overhead electrified area.
Area: All Areas   Usage: High   Status: Obsolescent
[18.11] Sign denoting exit from overhead electrified area.
Area: All Areas   Usage: High   Status: Obsolescent

A later design of warning sign for overhead electrified lines has a double flash symbol [18.12]. This sign has occasionally also been used away from overhead electrified areas to denote power lines crossing over the railway. A similar sign, with the words "live rails", may be used to denote the approach to an area of third rail electrification [18.13].

[18.12] Warning sign at entrance to overhead electrified area.
Area: All Areas   Usage: High   Status: Obsolescent
[18.13] Warning sign at entrance to third rail electrified area.
Area: All Areas   Usage: Medium   Status: Obsolescent

In 1984, a flood indicator in the form of a miniature colour light signal was provided at the east end of Silvertown Tunnel on the North Woolwich line. Normally a white aspect was displayed [18.14] but in the event of flooding, a red aspect was displayed [18.15]. A similar flood indicator was installed on the adjacent goods line in 1985, both indicators working simultaneously.

[18.14] Flood Warning Signal (normal aspect).
Area: Silvertown Tunnel   Usage: Low   Status: Historical
[18.15] Flood Warning Signal ('stop' aspect).
Area: Silvertown Tunnel   Usage: Low   Status: Historical

On the DC electrified lines in the Liverpool area, special arrangements exist to advise drivers during times of reduced power supply. During periods when it is necessary to reduce electrical loading on the system, a board bearing a large letter "E" in yellow on a black background [18.16] will be exhibited at the stopping point of each station within the affected section. The sign indicates to the driver that the 'series' position of the controller must be used until a station is reached where an "E" board is not exhibited.

[18.16] "E" Board.
Area: Liverpool area   Usage: Medium   Status: Current

On AC electrified lines, a neutral section is a short earthed section of overhead wire incorporating insulators to provide an electrical break between different supply phases or a change of system voltage. Drivers of electric trains should reduce power when approaching a neutral section and must not stop in a neutral section, other than in an emergency. In 1988, signs were introduced to mark the approach to and site of an overhead neutral section. Both signs bear the same symbol against a black or white background, respectively [18.17 & 18.18].

[18.17] Neutral Section Warning Board. Click Here for Photo
Area: All Areas   Usage: High   Status: Current
[18.18] Neutral Section Indication Board.
Area: All Areas   Usage: High   Status: Current

The Channel Tunnel, opened in 1994, is electrified on the 25 kV AC overhead wire system. Since the existing railways near the U.K. portal of the Channel Tunnel were electrified on the 750 V DC third rail system, drivers of all trains running between the two systems were required to carry out a traction current changeover procedure. Signs marked the point where the 25 kV overhead wires end, these comprising a circular black board with "25000" in white and a red diagonal cross [18.19].

[18.19] End of Eurotunnel Catenary Supply.
Area: Cheriton   Usage: Low   Status: Uncertain

The various signs that are installed to give instructions to drivers of electric trains passing through the traction current changeover zones were of the same design as the signs used on the French railway system (SNCF) [18.20 - 18.24]. These signs were installed at Dollands Moor in 1993 in readiness for the opening of the Channel Tunnel, and also between Kensington and North Pole on the West London Line.


The sign provided at the start of the traction current changeover zone [18.20] instructs the driver to open the main circuit breakers to shut off the power, and to lower the pantograph(s) or raise the conductor rail shoes in preparation for the changeover.

[18.20] Warning sign for traction current changeover zone. Click Here for Photo
Area: Various   Usage: Medium   Status: Current

For a changeover from AC to DC traction power, another sign marks the position by which the pantograph(s) must be lowered. This sign depicts a pair of solid white shapes, each resembling the cross section of a plano-concave lens, set horizontally against a square black background with a white border [18.21]. The driver may lower the retractable shoegear and the train may take DC traction power. A subsidiary plate may be fitted showing the voltage type to be selected [18.22] (these are not fitted between Kensington and North Pole).

[18.21] Execute Sign for Lower Pantograph(s).
Area: Various   Usage: Medium   Status: Current
[18.22] Execute Sign for Lower Pantograph(s), with subsidiary plate. Click Here for Photo
Area: Various   Usage: Medium   Status: Current

For a changeover from DC to AC traction power, a sign marks the position by which the shoegear must be raised. This sign has a similar appearance to the 'lower pantograph' sign described above, but rotated through 90° [18.23]. The driver may raise the pantograph(s) and the train may take AC traction power. A subsidiary plate may be fitted showing the voltage type to be selected [18.24] (these are not fitted between Kensington and North Pole).

[18.23] Execute Sign for Raise Pantograph(s).
Area: Various   Usage: Medium   Status: Current
[18.24] Execute Sign for Raise Pantograph(s), with subsidiary plate.
Area: Various   Usage: Medium   Status: Current