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Section 8: Over-run Prevention and Mitigation

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In some instances, extra measures have been implemented to guard against the possibility of an over-run (i.e. prevention) or to minimise the consequences of an over-run where one has taken place (i.e. mitigation). An over-run can take place at a station stop or, rather more seriously, past a signal that is showing a 'danger' indication. The latter occurrence has come to be termed a 'SPAD' - Signal Passed At Danger.



In complex layouts, line identifiers were sometimes fitted to signals (particularly if gantry-mounted), where there were many adjacent lines and signals [8.1]. This helped drivers to pick out the signal that applied to their train.

[8.1] Line Identifier.
Area: All Areas   Usage: High   Status: Historical

To enable drivers to locate their position, the Southern Railway had a practice of installing yellow (or amber) location lights [8.2] on the approach to passenger halts where no signals existed. These lights were commonly provided upon closure of a signal box and the consequent removal of signals from the vicinity of a passenger station. Exceptionally, the light was only displayed for trains booked to stop at the halt during darkness. At some locations, a white location light was used [8.3].

[8.2] Location Light (yellow).
Area: Southern Railway   Usage: Medium   Status: Historical
[8.3] Location Light (white).
Area: Southern Railway   Usage: Medium   Status: Historical

In December 1928, a fog location lamp was provided 50 yards on the approach to a signal at Borough Market Junction (Southern Railway). The lamp had a letter "F" on the face [8.4] and was only switched on during foggy weather. It was short-lived, being removed in April 1929.

[8.4] Fog Location Lamp.
Area: Borough Market Junction, Southern Railway   Usage: Low   Status: Historical

In 1928, a location board was provided 50 yards on the approach to signals at Vauxhall on the Southern Railway, to enable drivers to locate their position during foggy weather. This took the form of a rectangular board with alternate black and white squares [8.5]. It was replaced by a larger board bearing diagonal black and white stripes in 1929 [8.6].

[8.5] Fog Location Board.
Area: Vauxhall, Southern Railway   Usage: Low   Status: Historical
[8.6] Fog Location Board.
Area: Vauxhall, Southern Railway   Usage: Low   Status: Historical

When King's Cross (LNER) was resignalled in 1932, part of the layout was referred to as "A" route to "E" route. Identification letters, illuminated at night, were fitted to either side of the signal gantry directly above the lines to which they referred [8.7]. The corresponding letters also appeared on permanent speed restriction signs applying over those routes (see [13.14]).

[8.7] Identification Letter (e.g. route "A").
Area: King's Cross, LNER   Usage: Medium   Status: Historical

In 1933, the Southern Railway provided experimental fog location boards or posts at Earlswood and Haywards Heath. At Earlswood, a large square board with vertical stripes [8.8] was installed on the skew to the track, 100 yards on the approach to a signal. White posts [8.9] were installed 100 yards on the approach to two signals at Haywards Heath. The fog location board and posts at both places were removed in 1934.

[8.8] Experimental Fog Location Board.
Area: Earlswood, Southern Railway   Usage: Low   Status: Historical
[8.9] Experimental Fog Location Post.
Area: Haywards Heath, Southern Railway   Usage: Low   Status: Historical

In 1943, a white indicator plate was provided on the approach to Rogate station (Southern Railway) [8.10], to allow drivers to locate their position.

[8.10] Location Indicator.
Area: Rogate, Southern Railway   Usage: Low   Status: Historical

As early as 1956, trials took place with the provision of countdown markers on the approach to a distant signal at Newark (Eastern Region).

In the 1960s, marker lights were fixed to the wall of Glasgow Queen Street High Level Tunnel (Scottish Region) to assist drivers in locating a signal in the tunnel in conditions of poor visibility. There is a steep downhill gradient on the approach to the signal concerned. The marker lights comprised groups of continuously lit white lights (three at 108 yards, two at 62 yards, and one at 19 yards from the signal).

In the early 1960s, the Southern Region carried out experiments with countdown markers on the approaches to semaphore signals between Esher and West Byfleet. These had horizontal black stripes on a white background and were installed at 75 yards, 50 yards and 25 yards in rear of each signal [8.11]. Their provision was connected with the lack of AWS on the Southern Region at that time.

[8.11] Countdown Markers ( (a) - Outer board; (b) - Intermediate board; (c) - Inner board ).
Area: Esher - West Byfleet   Usage: Unknown   Status: Historical

In 1972, countdown markers were provided in the Severn Tunnel (Western Region) on the approaches to signals N166 (Down line) and N185 (Up line). These markers took the form of illuminated stencil indicators, lit only when the corresponding signal displayed a 'danger' aspect. They were installed at 900 yards, 600 yards and 300 yards in rear of the signal and showed three, two or one diagonal bars, respectively [8.12]. In 1974, permanently illuminated marker boards numbered "3", "2" and "1" were provided on the approaches to both signals at distances of 150 yards, 100 yards and 50 yards, respectively [8.13].

[8.12] Countdown Markers ( (a) - Outer board; (b) - Intermediate board; (c) - Inner board ).
Area: Severn Tunnel   Usage: Low   Status: Historical
[8.13] Marker Boards.
Area: Severn Tunnel   Usage: Low   Status: Historical

In 1975, countdown markers were installed in Chipping Sodbury Tunnel (Western Region) on the approach to signal DB102 on the Down Badminton line.

In 1987, a series of signs was provided to notify drivers of the approaches to Grantham and Newark North Gate stations on the East Coast Main Line (Eastern Region). A sign, showing the name of the station concerned, was installed at a distance of two miles on the approach side [8.14]. Beyond this sign, countdown markers with black diagonal stripes were erected at distances of ¾ mile, ½ mile and ¼ mile before the station [8.15].

[8.14] 'Station Ahead' Board (e.g. 2 miles to Newark).
Area: Grantham / Newark North Gate   Usage: Low   Status: Uncertain
[8.15] Countdown Markers ( (a) - Outer board; (b) - Intermediate board; (c) - Inner board ).
Area: Grantham / Newark North Gate   Usage: Low   Status: Uncertain

On the Scottish Region, signal M183 at Uddingston had been passed at 'danger' on numerous occasions. Although the sighting was good, drivers of light engines in particular had been misjudging their braking on the downhill approach to the signal. The problem was addressed in 1987 by the provision of experimental countdown markers on the approach to the signal. The markers, which had red diagonal bars on a white rectangular background [8.16], were installed at 436 yards, 294 yards and 160 yards in rear of the signal. This style of countdown marker was subsequently adopted nationally as one means of reducing SPAD occurrences at signals that have a history of such incidents or are considered to be 'high risk'. As standard, the markers are installed at 300 metres, 200 metres and 100 metres from the signal.

[8.16] Countdown Markers ( (a) - Outer board; (b) - Intermediate board; (c) - Inner board ).
Area: All Areas   Usage: High   Status: Obsolescent

In 1988, experimental countdown markers were installed on the approach to certain signals at Reading East and Thatcham (Western Region), as well as two signals at Preston (London Midland Region). In each case, the markers, which had black diagonal stripes on a white background [8.17], were installed at 300 yards, 200 yards and 100 yards in rear of the signal concerned.

[8.17] Countdown Markers ( (a) - Outer board; (b) - Intermediate board; (c) - Inner board ).
Area: Various   Usage: Low   Status: Historical

In 1990, notice boards were placed on each rail approach to Irvine station (Scottish Region) for the purpose of preventing station over-runs. These were square white boards bearing the words "Irvine station 1000yds" surrounded by a yellow border [8.18].

[8.18] 'Station Ahead' Board. Click Here for Photo
Area: Irvine   Usage: Low   Status: Obsolescent