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Section 29: Signs for Engineering Trains and Test Trains

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The signs described in this section are applicable only to specific types of engineering trains or to trains undergoing tests. They are disregarded by drivers of ordinary trains.


Lineside indicators were provided on the line between New Mills South Junction and Ambergate (London Midland Region) early in 1968 in connection with braking tests for the UIC Braking Sub-Committee, which lasted for a few weeks. Four different types of indicators were provided, each with a distinctive appearance. One type of indicator took the form of a diagonal cross with yellow and black vertical lines [29.1], one was a diamond shape with a black outside and a white centre [29.2], one was a square with a red outside and a white centre [29.3], and one was a triangle with a red outside and a white centre [29.4].

[29.1] Brake Test Indicator.
Area: New Mills South Junction - Ambergate   Usage: Low   Status: Historical
[29.2] Brake Test Indicator.
Area: New Mills South Junction - Ambergate   Usage: Low   Status: Historical
[29.3] Brake Test Indicator.
Area: New Mills South Junction - Ambergate   Usage: Low   Status: Historical
[29.4] Brake Test Indicator.
Area: New Mills South Junction - Ambergate   Usage: Low   Status: Historical

In 1974, square yellow marker boards with a letter "B" [29.5] were installed beside the Up and Down lines between Derby and Burton-on-Trent (London Midland Region) in connection with Research Department tests.

[29.5] "B" Marker Board.
Area: Derby - Burton-on-Trent   Usage: Low   Status: Historical

The Advanced Passenger Train (APT) was a train developed by British Rail in the 1970s, which had a tilt system that enabled it to travel at higher speeds than conventional trains over curved sections of track. The first version of this train, the APT-E ("E" for "experimental"), made test runs on the main line from 1972 until 1976. In connection with these tests, a series of marker boards was erected alongside the Down Main and Down Fast lines between Cricklewood and Leicester on the Midland Main Line (London Midland Region) in March 1975. Three different types of boards were provided, each exhibiting a letter in black. One type of board was a yellow diamond shape [29.6]. The other types of boards both consisted of a white square [29.7], some of which had diagonal red lines through the letter [29.8]. These boards were removed in 1976, although similar boards (excluding [29.8]) were installed on the Main and Fast lines between Crewe and Carnforth in September 1977.

[29.6] APT-E Test Marker.
Area: Cricklewood - Leicester / Crewe - Carnforth   Usage: Medium   Status: Historical
[29.7] APT-E Test Marker.
Area: Cricklewood - Leicester / Crewe - Carnforth   Usage: Medium   Status: Historical
[29.8] APT-E Test Marker.
Area: Cricklewood - Leicester   Usage: Medium   Status: Historical

In July 1975, a square white board [29.9] was installed at the lineside between Cholsey and Goring & Streatley (Western Region) in connection with certain test trains.

[29.9] Test Train Board.
Area: Cholsey - Goring & Streatley   Usage: Low   Status: Historical

In 1977, marker boards bearing yellow diagonal stripes on a black background [29.10] were installed at various sites between Kingston and Shepperton (Southern Region) in connection with brake testing. Marker boards of the same design were provided at various sites between Woking and Basingstoke in 1978, replacing previously installed markers of another type.

[29.10] Brake Test Marker Board.
Area: Kingston - Shepperton / Woking - Basingstoke   Usage: Medium   Status: Historical

The next version of the Advanced Passenger Train, the APT-P ("P" for "prototype"), was introduced in 1979 and later entered passenger service on the West Coast Main Line. The higher speeds at which these trains were permitted to run were in due course continuously indicated to drivers on a cab display, by a system called C-APT (Control APT). For the duration of the tests which commenced in 1979, however, special lineside marker boards were affixed to electrification structures between Carnforth (London Midland Region) and Glasgow Central (Scottish Region) via Beattock. The sign at the commencement of the special permissible speed was a square board with a white background [29.11], while the sign at the braking point where the permissible speed was reduced was a diagonal board with a yellow background [29.12].

[29.11] Commencement of indicated Permissible Speed for APT-P.
Area: Carnforth - Glasgow Central   Usage: Low   Status: Historical
[29.12] Braking Point for indicated Lower Permissible Speed ahead for APT-P.
Area: Carnforth - Glasgow Central   Usage: Low   Status: Historical

Further lineside marker boards were provided in May 1981 between Beattock and Carstairs (Scottish Region) in connection with testing of the APT-P, displaying a figure on either a white triangle [29.13] or a yellow square [29.14]. The APT-P was withdrawn from passenger service in 1985.

[29.13] APT-P Test Marker.
Area: Beattock - Carstairs   Usage: Low   Status: Historical
[29.14] APT-P Test Marker.
Area: Beattock - Carstairs   Usage: Low   Status: Historical

'Sandite' is a substance applied to the rail head to improve adhesion between wheel and rail. It is typically applied at sites where braking regularly occurs, such as on the approaches to stations. One method of applying Sandite is by a special train. To assist drivers of these trains, application sites on the Southern Region were initially marked by groups of sleepers painted white (four sleepers as an advance warning on the approach to a site, three at the commencement, and two at the termination). The Southern and Western Regions began installing lineside marker boards at Sandite application sites in 1987. The first marker, an upright yellow rectangle with three black diagonal bars [29.15], gives advance warning of an application site. This marker is followed by a similar yellow board with two bars [29.16] at the point where application should begin and finally a board with just one bar [29.17] at the point where application should end. These markers were later adopted as standard in all regions except the Scottish Region.

[29.15] Advance Warning of Sandite Application Site.
Area: All Areas except Scottish Region   Usage: High   Status: Current
[29.16] Commencement of Sandite Application Site.
Area: All Areas except Scottish Region   Usage: High   Status: Current
[29.17] Termination of Sandite Application Site.
Area: All Areas except Scottish Region   Usage: High   Status: Current

Although it is not a standard sign, a yellow marker with a letter "P" [29.18] is provided at some locations to denote that the application of Sandite is prohibited.

[29.18] Sandite Prohibition Marker.
Area: Salisbury - Exeter   Usage: Low   Status: Uncertain