Section 12: Signs for Train Protection Systems and Cab Signalling

(Page 2 of 3)

An AWS reminder board was installed at Warwick Parkway station upon its opening in September 2000, as a safeguard against a driver forgetting a 'caution' aspect displayed by the previous signal while stopped at the station. The lower part of the board included a picture of an AWS 'sunflower' cab indication underneath the words "check AWS" [12.17]. The board was removed in January 2002.

[12.17] AWS Reminder Board. Area: Warwick Parkway   Usage: Low   Status: Historical

In December 2001, signals between Bridlington and Seamer were fitted with AWS equipment, with the exception of the distant signals for Gristhorpe level crossing. To alert drivers to this omission, the posts of the preceding stop signals (one at Seamer South Junction and two at the north end of Filey station) were each fitted with a large board worded "no AWS for Gristhorpe" [12.18]. The boards were removed in May 2007 upon the installation of AWS equipment at the signals concerned.

[12.18] "No AWS for Gristhorpe" Sign. Area: Seamer South Junction / Filey   Usage: Low   Status: Historical

Experimental AWS reminder signs were installed beyond Hurst Green and Betchworth stations (Southern Region) in December 2002. Both bear a large image of a 'sunflower' on a square board with black and yellow surrounds [12.19].

[12.19] AWS Reminder Sign. Area: Hurst Green / Betchworth   Usage: Low   Status: On Trial

In preparation for the opening of the first section of the Channel Tunnel Rail Link (CTRL) in 2003, ordinary 'AWS gap' signs (see [12.4 & 12.5]) were provided at places where lines signalled with lineside signals abut lines with cab signalling (Fawkham Junction, Ashford and Dollands Moor). These replaced the previous signs at Dollands Moor (see [12.12 & 12.13]). At the same time, warning signs were installed approaching the areas of commencement of cab signalling, with the word "cab" on a white background [12.20]. This sign is placed some distance before the sign that marks the actual commencement of cab signalling (see [12.14]). A revised style of sign denoted the end of cab signalling, with the word "cab" on a white background and a red cross superimposed [12.21].

[12.20] Warning of Commencement of Cab Signalling. Area: Various   Usage: Medium   Status: Current	[12.21] End of Cab Signalling. Area: Various   Usage: Medium   Status: Current

The first section of the CTRL opened in September 2003, between Fawkham Junction and the Channel Tunnel. This was Britain's first high-speed line. The opening of the second section in November 2007 completed the route, which now runs between London St. Pancras and the Channel Tunnel. High-speed lines do not have lineside signals, because a driver could not reasonably be expected to read and interpret a signal aspect at high speed. Instead, cab signalling is used, with fixed markers placed at the lineside to mark the start of each block section. The CTRL is signalled with a cab signalling system called TVM. This is the same system as used in the Channel Tunnel itself, as well as on the high-speed lines in France, where high-speed lines had been in operation for many years beforehand. The letters "TVM" stand for 'Transmission Voie-Machine', which means 'Track to Train Transmission'. The British block markers are based on the French 'repères', bearing a solid yellow triangle on a blue square background [12.22]. The apex of the triangle points towards the line to which it applies. The marker indicates to the driver the position at which the train must come to a stand when a 'stop' indication is shown on the cab signalling display.

A shunt marker is provided to identify the origin of a shunting movement at places where no block marker is provided. A shunt marker is a five-sided shape and has a white chevron on a violet background [12.23]. The tip of the chevron points towards the line to which it applies. Every shunt marker on the CTRL is provided with an auxiliary signal (see [9.60]), which is illuminated when the shunt marker is 'opened'. On the French high-speed lines, the equivalent of the shunt marker is the 'jalon de manœuvre', similarly coloured but different in shape.

[12.22] TVM Block Marker / CBTC Block Marker (e.g. applies to the line on the right). Area: CTRL / Crossrail   Usage: High   Status: Current	[12.23] TVM Shunt Marker / ETCS Shunt Entry Board (e.g. applies to the line on the right). Area: CTRL / Cambrian Lines   Usage: Medium   Status: Current

The national programme of Train Protection & Warning System (TPWS) fitment reached the lines worked by the Radio Electronic Token Block (RETB) system in 2003. RETB is a low-cost signalling system that replaces working stop signals with stop boards, some of which require TPWS fitment. Because signalmen receive no indication of TPWS failures in an RETB area, a 'Lineside Status Indicator' (LSI) comprising a blue light is installed at each TPWS-fitted stop board to inform drivers whether the TPWS equipment is operating correctly. A steady blue light in the LSI [12.24] means that the TPWS is in its normal state, energised and providing overrun protection. The blue light will flash [12.25] when the TPWS equipment is de-energised, which occurs when a correct token is issued (and any ground frame or plunger is operated). If the light in the LSI is out, the driver must report it to the signalman as a fault. This equipment was initially commissioned at Tywyn on the Cambrian Line, in June 2003.

[12.24] TPWS Indicator (steady). Area: Tywyn   Usage: Low   Status: Historical	[12.25] TPWS Indicator (flashing). Area: Tywyn   Usage: Low   Status: Historical

A few weeks after they were brought into use, the backboards of the LSIs at Tywyn were changed to black. The black backboard became the standard for future installations of LSIs [12.26 & 12.27].

[12.26] TPWS Indicator (steady). Area: Various   Usage: High   Status: Current	[12.27] TPWS Indicator (flashing). Area: Various   Usage: High   Status: Current

If a stop board fitted with a TPWS indicator can be approached at speed, a repeater may be necessary. This particularly applies at a TPWS-fitted stop board at an intermediate token exchange point where there is no crossing loop. Where a repeater TPWS indicator is provided, it repeats the indication at the stop board and is mounted below the distant board on the approach to it [12.28 & 12.29]. The first repeater LSI was put on trial for two days in September 2003, fitted to the Up distant board at Evanton. It was fully commissioned in October 2003 and was soon followed by others.

[12.28] TPWS Repeater Indicator (steady). Area: Various   Usage: Low   Status: Current	[12.29] TPWS Repeater Indicator (flashing). Area: Various   Usage: Low   Status: Current

A TPWS repeater indicator may also be provided on the approach to a TPWS-fitted stop board with restricted sighting, in which case it can be independently mounted [12.30 & 12.31]. One of these was provided at Oban in October 2003.

[12.30] TPWS Repeater Indicator (steady). Area: Various   Usage: Low   Status: Current	[12.31] TPWS Repeater Indicator (flashing). Area: Various   Usage: Low   Status: Current