Section 14: Temporary Speed Restriction Signs

(Page 2 of 3)

In 1982, trials commenced that entailed a black and white striped board with a central flashing white light [14.20] being positioned on the approach to various T.S.R. warning boards (between the warning board and its associated AWS magnet). This was in order to assess its effectiveness in connection with emergency speed restrictions. An emergency speed restriction is one that has not been advised in the notices, is a lower speed or applies at a time not shown. The new board was intended to end the practice of stationing handsignalmen with detonators at warning boards associated with such speed restrictions.

[14.20] Experimental Emergency Indicator.

The directional indication [14.21] was on trial from 1982 and fully introduced in 1986. This is fitted to a warning board to indicate that the T.S.R. speed indicator is situated on a left-hand or right-hand divergence ahead.

[14.21] Warning Board with Directional Indication (e.g. applicable to T.S.R. on right-hand divergence).

From 1986, yellow versions of the illuminated T.S.R. signs were on trial [14.22 - 14.29] and gradually they superseded the blue signs formerly used.

[14.22] Warning Board.	[14.23] Warning Board for a Differential T.S.R.	[14.24] Warning Board with Directional Indication (e.g. applicable to T.S.R. on left-hand divergence).


[14.25] Speed Indicator.	[14.26] Differential Speed Indicators.	[14.27] Termination Indicator.

[14.28] Warning Board with Spate Indication.	[14.29] Spate Indication in lieu of speed indicator.

Following the initial trials in 1982 of an indicator for use with emergency speed restrictions (see [14.20]), further trials took place in 1986 on each of the five B.R. Regions. The new design of indicator, with two high-powered flashing lights [14.30], was positioned adjacent to the AWS equipment in rear of a T.S.R. warning board. While the trials were a success, a revised version of indicator [14.31] was on trial in 1987 and introduced as standard the following year. Additional AWS equipment is installed in rear of each emergency indicator. A miniature version of the indicator was also introduced, on which the lower black shape is omitted [14.32].

[14.30] Experimental Emergency Indicator.	[14.31] Emergency Indicator.	[14.32] Emergency Indicator for use in areas of limited clearance.

The 'repeating warning board' [14.33] was introduced in 1992. It serves as a reminder to drivers of a T.S.R. ahead, where a station platform intervenes between the warning board and the speed indicator. If the T.S.R. speed indicator is less than 300 yards ahead of the platform then no repeating warning board need be provided. In 1993, use of the repeating warning board was extended to include connections from sidings that fall between the warning board and the speed indicator.

[14.33] Repeating Warning Board.

Both lines across the Forth Bridge are signalled bi-directionally to allow all traffic to be worked over one line, in both directions, while the other line is out of use and under possession for engineering work. For all pre-planned work, a temporary speed restriction of 20 m.p.h. will be imposed for right-direction movements. Wrong-direction movements are subject to a 20 m.p.h. permanent speed restriction. New special arrangements for signage associated with these pre-planned temporary speed restrictions on the bridge were introduced in c.1993. No warning board or AWS equipment will be provided. The speed indicator is a blue circular board [14.34] that replaces the permanent speed restriction sign that is normally exhibited on the approach to the bridge. The termination indicator has a white "T" on a blue background (see [14.13]). Drivers may accelerate as soon as the front of the train has passed the termination indicator. If the work is unplanned or the restriction is to be more severe than 20 m.p.h., standard T.S.R. signage including warning boards and AWS will be provided.

[14.34] Speed Indicator (Forth Bridge).

In 1996, use of directional indicators, as previously used with T.S.R. warning boards (see [14.24]), was extended for use on speed indicators [14.35] where the T.S.R. applies through a divergence immediately ahead.

[14.35] Speed Indicator with Directional Indication (e.g. applicable to left-hand divergence).

Reflectorised boards for temporary speed restrictions were introduced from 1996, having been on trial since 1994. While this change did not alter the appearance of most of the boards, the new warning board was given two white spots [14.36 - 14.39] instead of flashing white lights. A revised design of repeating warning board [14.40] was introduced at the same time.

[14.36] Reflectorised Warning Board.	[14.37] Reflectorised Warning Board for a Differential T.S.R.	[14.38] Reflectorised Warning Board with Directional Indication (e.g. applicable to T.S.R. on right-hand divergence).

[14.39] Reflectorised Warning Board with Spate Indication.	[14.40] Repeating Warning Board.

A track condition that presents itself as a series of regular dips in the vertical alignment is referred to as 'cyclic top'. It has the potential to cause a derailment unless a T.S.R. is imposed. In 1998, a trial of signage indicating a cyclic top restriction [14.41] was carried out between Tonbridge and Redhill.

[14.41] Cyclic Top Restriction Sign.

A reflectorised version of the emergency indicator without any lights was on trial from 1999. Following comments received from traincrews, a modified indicator was developed in 2000 incorporating two flashing white lights, as per the standard non-reflectorised design.

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