Section 14: Temporary Speed Restriction Signs
(Page 1 of 3)
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.
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If the restriction was to continue for a lengthened period, a warning board might be positioned on the approach to the site [14.1]. If a warning board was erected, the second handsignalman and the detonators could be dispensed with, except during fog or falling snow. The green painting of the warning board was consistent with the early use of green in signal lights to mean 'caution' (see Section 1 and Section 2). After sunset or during fog or falling snow, one green and one white lamp were displayed side by side in the warning board.
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[14.1] Warning Board.
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If a warning board was erected, the beginning and end of the restriction might be marked by a commencement [14.2] and termination indicator [14.3] respectively, instead of by handsignalman. Normal speed may be resumed as soon as the rear of the train has passed the termination indicator. 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.
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[14.2] Commencement Indicator.
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[14.3] Termination Indicator.
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Some companies would place an illuminated indicator above the warning board, showing the speed in miles per hour that the train must slow down to [14.4]. After the 1923 Grouping, the LMS, GWR and SR provided a speed indication, but the LNER did not.
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[14.4] Warning Board with Speed Indication.
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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 [14.5]. Gas-lit warning boards, introduced in the 1960s, exhibited two white lights instead [14.6].
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[14.5] Yellow Warning Board.
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[14.6] Gas-lit Warning Board.
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Speed indicators [14.7] replaced commencement indicators (see [14.2]) 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 [14.8]. The warning board will also show both speeds, one above and one below [14.9]. 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.
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[14.7] Speed Indicator.
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[14.8] Differential Speed Indicators.
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[14.9] Warning Board for a Differential T.S.R.
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This type of floodlit warning board was in use from c.1975 [14.10].
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[14.10] Floodlit Warning Board.
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Experimental battery-lit warning boards and T.S.R. indicators first went on trial in 1980. The new warning board was rectangular in shape and displayed two white flashing lights [14.11]. 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 [14.12]. The termination indicator had a white "T" on a blue background [14.13].
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[14.11] Battery-lit Warning Board.
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[14.12] Speed Indicator.
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[14.13] Termination Indicator.
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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 [14.14 & 14.15], 'spate' being an acronym for 'Speed Previously Advised Terminated Early'. The spate indication was on trial from 1980 and fully introduced in 1983.
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[14.14] Spate Indication at a Warning Board.
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[14.15] Spate Indication in lieu of a speed indicator.
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When battery-lit signs were adopted for general use at T.S.R.s (by 1983), the colours of the speed indicators were reversed such that they had white figures on a blue background [14.16 & 14.17], thus making them the same as the speed indication displayed at the warning board (see [14.11]). In the case of a warning board referring to a differential speed restriction, both speeds are exhibited above the warning board [14.18].
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[14.16] Speed Indicator.
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[14.17] Differential Speed Indicators.
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[14.18] Battery-lit Warning Board for a Differential T.S.R.
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[14.19] Battery-lit Warning Board with Spate Indication.
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