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Section 14: Temporary Speed Restriction Signs

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While permanent way works are taking place or for other reasons it may be necessary to temporarily restrict the speed of trains to less than the normally permitted speed. The earliest method of advising drivers was to position a handsignalman at the site of the temporary speed restriction (T.S.R.), with a further handsignalman positioned half a mile or so on the approach. The latter would place a detonator on the rail and exhibit a green handsignal waved slowly from side to side.

The Great Western Railway had introduced the warning board by 1905 [14.1]. One of these boards might be positioned on the approach to a T.S.R. if it was to continue for a long period of time. If a warning board was erected, the second handsignalman and the detonators could be dispensed with, except during fog or falling snow. The shape and colour of the warning board were clearly derived from the 'caution' indication of the GWR 'caution board' (see [1.31]). After sunset or during fog or falling snow, one green and one white lamp were displayed side by side in the warning board. Some other companies adopted the same style of warning board.

[14.1] Warning Board.

If a warning board was erected, the beginning and end of the restriction might be marked by a commencement indicator and a termination indicator respectively, instead of by handsignalman. Normal speed may be resumed as soon as the rear of the train has passed the termination indicator. On the Great Central Railway, the commencement indicator was a green oval board which displayed two green lights side by side at night [14.2] and the termination indicator was a white diamond shaped board showing one green light at night [14.3]. The Great Eastern Railway placed a green banner and green light at the commencement of the restriction, and used a termination indicator in the form of a tall white board shaped like a letter "T", showing a white light at night [14.4].

[14.2] Commencement Indicator (GCR).	[14.3] Termination Indicator (GCR).	[14.4] Termination Indicator (GER).

From 1914, the London & North Western Railway would place an indicator below the warning board, showing the speed in miles per hour that the train's speed must be reduced to [14.5]. The LNWR's commencement and termination indicators comprised white circular boards bearing the letters "C" and "T", respectively [14.6 & 14.7].

[14.5] Warning Board with Speed Indication (LNWR).	[14.6] Commencement Indicator (LNWR).	[14.7] Termination Indicator (LNWR).

From c.1916, the illuminated speed indications at LNWR warning boards were exhibited above the warning board [14.8].

[14.8] Warning Board with Speed Indication.

Standard signage for T.S.R.s was introduced nationally in 1917. This included the existing style of warning board (see [14.1] and [14.8]) as well as new forms of commencement and termination indicators. The commencement indicator had a black letter "C" on a white background [14.9] and the termination indicator had a white "T" on a black background [14.10]. Both indicators were illuminated. For a T.S.R. located inside a long tunnel, the commencement and termination indicators could be dispensed with and audible signals given instead by means of gongs.

[14.9] Commencement Indicator.	[14.10] Termination Indicator.

The warning boards were altered to have white edges c.1924 [14.11 & 14.12]. The ex-LNWR practice of displaying the speed above the warning board [14.12] was subsequently followed on all LMS lines. Around 1944, the GWR and Southern Railway adopted the same practice, but the LNER did not.

[14.11] Warning Board.	[14.12] Warning Board with Speed Indication.

From 1938, in colour light signalling areas, the Southern Railway used electrically floodlighted warning boards, which obviated the requirement for handsignalmen to be stationed at them during fog or falling snow.

In 1949, the warning boards were repainted yellow, by then the long-accepted colour meaning 'caution'. Two lamps with yellow lenses were exhibited at night [14.13]. Gas-lit warning boards, introduced in the 1960s, exhibited two white lights instead [14.14].

[14.13] Yellow Warning Board.	[14.14] Gas-lit Warning Board.

Speed indicators [14.15] replaced commencement indicators (see [14.9]) from 1968. These display the T.S.R. speed in addition to the speed indication at the warning board. Differential speed restrictions were introduced for T.S.R.s also in 1968. Where these are used, the speed indicator will display two speeds [14.16]. The warning board would also show both speeds, one above and one below [14.17]. The speeds apply as follows:

Top figure (lower speed) - Applicable to all trains, except passenger and empty coaching stock trains not conveying four-wheeled vehicles.
Bottom figure (higher speed) - Applicable only to passenger and empty coaching stock trains not conveying four-wheeled vehicles.

[14.15] Speed Indicator.	[14.16] Differential Speed Indicators.	[14.17] Warning Board for a Differential T.S.R.

This type of floodlit warning board was in use from c.1975 [14.18].

[14.18] Floodlit Warning Board.

Experimental battery-lit warning boards and T.S.R. indicators first went on trial in 1979. The new warning board was rectangular in shape and displayed two white flashing lights [14.19]. The speed indication exhibited at the warning board had white figures on a blue background, the colours being transposed on the speed indicator positioned in advance [14.20]. The termination indicator had a white "T" on a blue background [14.21].

[14.19] Battery-lit Warning Board.	[14.20] Speed Indicator.	[14.21] Termination Indicator.

When a T.S.R. had been advised in the notices but not imposed or was withdrawn earlier than published, it had been the practice that normal line speed would be shown in both the speed indicator and the warning board, in place of the T.S.R. speed. As an alternative it was proposed that the speed indications would be replaced by a special indicator termed a 'spate' indication [14.22 & 14.23], 'spate' being an acronym for 'Speed Previously Advised Terminated Early'. The spate indication was on trial from 1980 and fully introduced in 1983.

[14.22] Spate Indication at a Warning Board.	[14.23] Spate Indication in lieu of a speed indicator.

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