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Section 12; pages:
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Section 12: Signs associated with In-Cab Warning Systems
(Page 2 of 2)
At Fawkham Junction, Ashford and Dollands Moor in 2003, warning signs were installed approaching the area of commencement of cab signalling [12.17]. This sign is placed some distance before the sign that marks the actual commencement of cab signalling (see [12.12]). Also in 2003, a different sign was used to denote the end of cab signalling [12.18].
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[12.17] Warning of Commencement of Cab Signalling.
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[12.18] End of Cab Signalling.
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In 2003, ordinary 'AWS Gap' signs (see [12.3 & 12.4]) were installed at places where lines signalled with lineside signals abut lines with cab signalling. These replaced the special signs at Dollands Moor (see [12.10 & 12.11]).
During 2003, the Train Protection & Warning System (TPWS) was fitted to lines worked by the Radio Electronic Token Block (RETB) system. In the absence of lineside signals, an indication must be provided for drivers for the sole purpose of showing whether the TPWS equipment is operating correctly. A 'Lineside Status Indicator' (LSI) comprising a blue light was installed at each stop board fitted with TPWS equipment.
A steady blue light in the LSI means that the TPWS is in its normal state, energised and providing over-run protection [12.19]. The blue light will flash when the TPWS equipment is de-energised [12.20]. This 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.
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[12.19] TPWS Indicator (normal).
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[12.20] TPWS Indicator (flashing).
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A few weeks after they were brought into use, the backboards of the LSIs at Tywyn were altered to be black. The black backboard became the standard for future installations of LSIs [12.21 & 12.22].
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[12.21] TPWS Indicator (normal).
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[12.22] TPWS Indicator (flashing).
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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 [12.23 & 12.24]. The first repeater LSI was put on trial for two days in September 2003, fitted to the Up distant board at Evanton. It was finally commissioned in October 2003, and was soon followed by others.
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[12.23] TPWS Repeater Indicator (normal).
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[12.24] TPWS Repeater Indicator (flashing).
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A TPWS repeater indicator may be required if the stop board is not visible from the position where trains normally stop. One was provided at Oban in October 2003 [12.25 & 12.26].
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[12.25] TPWS Repeater Indicator (normal).
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[12.26] TPWS Repeater Indicator (flashing).
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The opening of Section 2 of the Channel Tunnel Rail Link in 2007 saw a return to the provision of AWS boundary signs with black backgrounds (see [12.10 & 12.11]), although the new 'end of AWS' signs have a single diagonal red stripe [12.28]. Note that the letters "AWS" on these signs may refer to the French KVB system rather than the BR AWS system. "KVB" stands for 'Contrôle de Vitesse par Balises', meaning 'Speed Control by Beacons'. KVB is in use on the CTRL approach to St. Pancras International station.
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[12.28] End of AWS.
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From 2009, the train-operated (hydro-pneumatic) points on lines worked by the No-Signalman Token Remote (NSTR) system are being converted to conventional power operation. As this work is carried out, TPWS indicators (see [12.21 & 12.22]) are being provided at the stop boards applicable to trains departing the crossing loop in the usual direction. These are in addition to the TPWS indications located inside the token instrument huts.
