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Section 13: Permanent Speed Restriction Signs

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Following a derailment on the curve at Morpeth on 7 May 1969, the British Railways Board agreed to the provision of advance warning indicators (AWIs) on approach to certain speed restrictions. The new indicators, which first appeared in 1971 and became known as 'Morpeth boards', had yellow figures within a yellow border on a circular black background [13.24]. They were placed at braking distance in rear of the start of the speed restriction and in many cases were floodlit at night. An advance warning indicator applicable to a speed restriction on a diverging route carried an additional directional arrow below [13.25]. A vertical arrow was exhibited below an advance warning indicator that applied to a speed restriction on the straight route beyond a diverging junction [13.26].

[13.24] Advance Warning Indicator. Area: All Areas   Usage: High   Status: Obsolescent	[13.25] Advance Warning Indicator with Directional Arrow (e.g. applicable to right-hand diverging route). Area: All Areas   Usage: Medium   Status: Historical	[13.26] Advance Warning Indicator with Vertical Arrow. Area: All Areas   Usage: Medium   Status: Historical

In August 1971, a speed restriction of 25 mph was experimentally imposed on Class 7, 8 and 9 freight trains over the lines between Hartford CLC Junction and Dee Marsh North Junction and between Dee Marsh Junction and Bidston Dee Junction, on the London Midland Region. Where a higher speed applied to other classes of trains, this was indicated by the bottom figure of a differential 'cut-out' speed restriction sign erected at the point of commencement [13.27]. Similar signs were installed on the line between New Mills South Junction and Cheadle Junction in September 1971, and between Burton-on-Trent and Knighton South Junction in January 1972.

[13.27] Differential Permanent Speed Restriction Sign. Area: London Midland Region (subsequently All Areas)   Usage: High   Status: Obsolescent

In February 1977, a 'cut-out' style speed restriction sign (see [13.17]) indicating a permissible speed of 125 mph on the Up Main line at Reading (Western Region) was replaced by an experimental indicator showing the figures "125" in reflective yellow on a black background [13.28].

[13.28] Experimental Permanent Speed Restriction Sign. Area: Reading   Usage: Low   Status: Historical

Where a change of permissible speed occurs within a tunnel, it may be indicated by a permanently illuminated indicator [13.29], for example in the central Liverpool area and on the lines approaching London King's Cross station.

[13.29] Illuminated Permanent Speed Restriction Indicator. Area: Various   Usage: Medium   Status: Uncertain

The Class 253 and 254 'High Speed Trains' (or 'InterCity 125s') were introduced to British Rail in 1976. Because of their superior braking performance, they were permitted to travel over specified sections of track at a higher speed than other trains. On the Western Region, a yellow triangle was placed on the posts of speed restriction signs, below the cut-out figures, to denote those places where a variation in the permissible speed for certain classes of trains applied. The triangle pointed up if the variation was higher [13.30] or down if it was lower [13.31]. Neither the permitted speed nor the application of the variation was stated, the details of which were to be found in the relevant Sectional Appendix. The first of these signs were installed in May 1977, marking the start of sections where a different permissible speed applied to HSTs.

[13.30] Differential Permanent Speed Restriction Sign. Area: Western Region   Usage: Low   Status: Historical	[13.31] Differential Permanent Speed Restriction Sign. Area: Western Region   Usage: Low   Status: Historical

Boards were installed on the East Coast Main Line in October 1977 at the start and end of sections where HSTs were permitted to run at 125 mph during daylight hours. The commencement boards were circular with a letter "A" [13.32], and the termination boards were square with a letter "B" [13.33]. These boards were installed as a temporary measure, at various sites between Peterborough and Darlington.

[13.32] HST Commencement Board. Area: East Coast Main Line   Usage: Low   Status: Historical	[13.33] HST Termination Board. Area: East Coast Main Line   Usage: Low   Status: Historical

Where an advance warning indicator was required on the approach to a permanent speed restriction applicable only to HSTs, it bore the letters "HST" above the speed figure [13.34].

[13.34] Advance Warning Indicator applicable to a permanent speed restriction for HSTs. Area: All Areas   Usage: Medium   Status: Historical

In 1979, experimental reflectorised permanent speed restriction signs were erected at Metropolitan Junction and Gillingham (Kent). Each sign had black figures on a circular yellow background, surrounded by a black border [13.35] and was therefore of similar appearance to an advance warning indicator (see [13.24]) with the colours reversed.

[13.35] Experimental Permanent Speed Restriction Sign. Area: Metropolitan Junction / Gillingham   Usage: Low   Status: Historical

Differential speed restrictions were already in existence in connection with temporary speed restrictions (see Section 14) and at some level crossings (see Section 16) when, c.1980, their use was extended to certain permanent speed restrictions. Where this applies, the PSR sign displays two speeds, one above the other (see [13.27]). Where an advance warning indicator is required, this will also show two speeds [13.36]. This form of differential speed restriction has come to be referred to as a 'standard differential' PSR, as distinct from a 'non-standard differential' PSR which specifies the relevant type of train by letters, e.g. "HST".

[13.36] Advance Warning Indicator applicable to a standard differential permanent speed restriction. Area: All Areas   Usage: Low   Status: Historical

Speed signs applicable only to HSTs were installed on the Scottish Region from 1981. The commencement sign was square in shape [13.37], and the termination sign was a diagonal board, which displayed a letter "T" instead of a speed [13.38]. Either sign may be provided in isolation or co-located with an ordinary speed sign. On passing a commencement sign, drivers of HSTs may disregard any ordinary signs indicating a lower speed, including any further signs ahead. Ordinary speed restriction signs indicating a higher speed continue to apply. Higher permissible speeds applicable to certain classes of diesel multiple unit trains were subsequently indicated by similar signs but with the letters "DMU" or "MU" instead of the letters "HST". Signs displaying only the letters "MU" also apply to HSTs and vice versa. Some signs at the Forth Bridge had two sets of letters, referring to HSTs and DMUs [13.39 & 13.40].

[13.37] Commencement Sign. Area: Scottish Region   Usage: High   Status: Obsolescent	[13.38] Termination Sign. Area: Scottish Region   Usage: High   Status: Obsolescent
[13.39] Commencement Sign applicable to HSTs and DMUs. Area: Forth Bridge   Usage: Low   Status: Historical	[13.40] Termination Sign applicable to HSTs and DMUs. Area: Forth Bridge   Usage: Low   Status: Historical

Pentagonal signs coloured yellow were installed between Dearne Junction and Moorthorpe (Eastern Region) in October 1984 to mark the commencement and termination of higher permissible speeds for HSTs. The commencement sign was an upward-pointing pentagon indicating the higher speed at which HSTs may travel [13.41]. This higher speed applied until a termination sign was reached, this being a downward-pointing pentagon indicating the lower speed to which HSTs must revert [13.42].

[13.41] Commencement Sign. Area: Dearne Junction - Moorthorpe   Usage: Low   Status: Historical	[13.42] Termination Sign. Area: Dearne Junction - Moorthorpe   Usage: Low   Status: Historical