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Section 23: Signs concerning Natural Hazards

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Rail operations can be adversely affected by events of nature such as high winds or leaf fall. The effects can be mitigated by the implementation of procedures, some of which entail the provision of special signs at the sites concerned. Flood indicators on electrified railways are covered in Section 18. See also The Pass of Brander Stone Signals for a description of a system for alerting drivers to the presence of fallen boulders.


Where railways run adjacent to forests, woods or orchards, etc., the risk of a lineside fire is higher than normal, especially when steam locomotives are operating. From 1959, lineside signs were erected at the commencement and termination of these zones. Both signs were in the form of a yellow disc, the commencement sign depicting the silhouette of a conifer [23.1] and the termination sign, a vertical black band [23.2].

[23.1] Entrance to zone of specially high fire risk.
Area: All Areas   Usage: Medium   Status: Obsolescent
[23.2] Exit from zone of specially high fire risk.
Area: All Areas   Usage: Medium   Status: Obsolescent

Trial high wind site warning signs were installed at Blisworth (Midlands Zone) on the West Coast Main Line in October 1998. The first sign on each line is an advance warning sign, consisting of a motorway-style flashing indicator alternately displaying "110 m.p.h." and "high winds" [23.3]. Fixed lineside signs are erected at the commencement [23.4] and termination [23.5] of the high wind site. Trains must run at reduced speed when the advance warning sign is illuminated. When these signs were brought into use in November of the same year, the speed displayed at the advance warning sign was changed to 80 m.p.h. [23.6].

[23.3] High Wind Site Advance Warning Sign.
Area: Blisworth   Usage: Low   Status: Historical
[23.4] High Wind Site Commencement Board.
Area: Blisworth   Usage: Low   Status: Uncertain
[23.5] High Wind Site Termination Board.
Area: Blisworth   Usage: Low   Status: Uncertain
[23.6] High Wind Site Advance Warning Sign.
Area: Blisworth   Usage: Low   Status: Uncertain

Certain areas are prone to problems with low rail adhesion caused by leaf fall. From 1999, warning signs were erected at known problem locations on the Midlands Zone. The first sign is an advance warning sign, consisting of a motorway-style flashing indicator alternately displaying the words "poor" and "adhesion" [23.7]. This sign will only be illuminated when poor adhesion conditions are known to exist at the site ahead. Fixed lineside signs are erected at the commencement [23.8] and termination [23.9] of the low adhesion site.

[23.7] Low Adhesion Site Advance Warning Sign.
Area: Midlands Zone   Usage: Medium   Status: Current
[23.8] Low Adhesion Site Commencement Board.
Area: Midlands Zone   Usage: Medium   Status: Current
[23.9] Low Adhesion Site Termination Board.
Area: Midlands Zone   Usage: Medium   Status: Current

From 1999, signs were installed at sites of low rail adhesion in the Reading area (Great Western Zone) and the Sussex area (Southern Zone). The commencement board bears the image of a leaf on a triangular sign with a yellow border [23.10]. The termination board is similar but has a red horizontal band across its centre [23.11]. There is no advance warning sign on the approach to the site.

[23.10] Low Rail Adhesion Site Commencement Sign. Click Here for Photo
Area: Great Western and Southern Zones   Usage: Medium   Status: Obsolescent
[23.11] Low Rail Adhesion Site Termination Sign.
Area: Great Western and Southern Zones   Usage: Medium   Status: Obsolescent

From 2000, octagonal signs were installed at low adhesion sites in the Scotland Zone. The commencement board [23.12] advises the distance over which poor adhesion can be expected. At the exit from the site, a termination board is provided [23.13].

[23.12] Low Rail Adhesion Site Commencement Board.
Area: Scotland Zone   Usage: Medium   Status: Current
[23.13] Low Rail Adhesion Site Termination Board.
Area: Scotland Zone   Usage: Medium   Status: Current

From 2000, signs of a different design were erected at low rail adhesion sites across the East Anglia Zone. These comprise a commencement sign depicting a leaf on a yellow triangular background [23.14] and a termination sign which is similar in appearance but has a black cross superimposed [23.15]. Both signs are exhibited to drivers only during the low adhesion season and have a centre hinge allowing them to be closed at other times of the year. When a sign is closed, a plain grey triangle is all that is visible. The same signs are used on railways in South Wales.

[23.14] Low Rail Adhesion Site Commencement Sign.
Area: East Anglia Zone / South Wales   Usage: Medium   Status: Obsolescent
[23.15] Low Rail Adhesion Site Termination Sign.
Area: East Anglia Zone / South Wales   Usage: Medium   Status: Obsolescent

In 2002, pairs of signs were installed at three low adhesion sites in the vicinity of Apperley Junction (Eastern Region). These applied only to drivers of Arriva Trains (subsequently Northern Rail), in connection with their defensive driving instructions at low adhesion sites. At each of the three sites, a sign with a yellow border [23.16] was followed by one with a red border [23.17]. These signs are removed and reinstated annually, as they only apply during the low adhesion season.

[23.16] "Low Adhesion" Sign.
Area: Apperley Junction   Usage: Low   Status: Obsolescent
[23.17] "Low Adhesion" Sign.
Area: Apperley Junction   Usage: Low   Status: Obsolescent

Part of the Cambrian Coast Line between Llanaber and Talybont stations runs alongside a sea wall. During strong winds or high tides, a speed restriction of 30 m.p.h. (50 km/h) may be imposed over part of this section. Special signs were erected in July 2007 to mark the beginning and end of the affected section of line. The commencement sign shows a 'wave' symbol on a triangular sign with a yellow border [23.18]. The termination sign is similar but has a diagonal band superimposed [23.19]. Normally, these signs can be disregarded. On occasions when the restriction is in force, the driver of each train will be verbally advised by the signalman at the previous token exchange point (or, since the replacement of the RETB signalling by ERTMS, at the previous block marker (see [2.127]) ).

[23.18] Weather Related Speed Restriction Commencement Sign.
Area: Llanaber - Talybont   Usage: Low   Status: Uncertain
[23.19] Weather Related Speed Restriction Termination Sign.
Area: Llanaber - Talybont   Usage: Low   Status: Uncertain

In October 2007, experimental low rail adhesion warning signs were put on trial on the approaches to Linlithgow and Polmont stations on the Edinburgh & Glasgow line. Normally the sign is closed and not visible to drivers. In the event of poor adhesion being reported, the sign will be opened to display a warning message [23.20].

[23.20] Low Rail Adhesion Warning Sign.
Area: Edinburgh - Glasgow   Usage: Low   Status: Uncertain

Around 2009, signs of a new design were provided at the commencement [23.21] and termination [23.22] of low rail adhesion sites on certain routes. These signs are often mounted directly underneath Sandite application site commencement markers and termination markers, respectively (see [29.7 & 29.8]).

[23.21] Low Rail Adhesion Site Commencement Sign.
Area: All Areas   Usage: Medium   Status: Current
[23.22] Low Rail Adhesion Site Termination Sign.
Area: Various   Usage: Medium   Status: Obsolescent

In 2009, South West Trains carried out trials of new signage for low rail adhesion sites. Small signs are exhibited at the stations before and after the low adhesion site, as opposed to at the site itself. The warning sign [23.23] and the termination sign [23.24] are placed at or near the car stop markers (see Section 21) at the appropriate stations. These signs are removed at the end of the leaf fall season.

[23.23] Low Rail Adhesion Warning Sign. Click Here for Photo
Area: South West Trains   Usage: Medium   Status: Uncertain
[23.24] Low Rail Adhesion Termination Sign.
Area: South West Trains   Usage: Medium   Status: Uncertain

In 2011, experimental low rail adhesion warning signs were put on trial at six stations on the line between Sheffield and Wakefield via Barnsley. In the event of low rail adhesion being reported, the appropriate sign will be opened to display a warning to the driver to expect low rail adhesion until the next station [23.25]. An AWS magnet is installed on the approach to each board, giving an audible warning in the cab. When a sign is not in use it remains closed and an AWS cancelling indicator is displayed (see [12.7]).

[23.25] Low Rail Adhesion Warning Sign.
Area: Sheffield - Wakefield   Usage: Medium   Status: On Trial

A new style of sign denoting the exit from a low rail adhesion site was introduced by 2013. The sign depicts a leaf on a square yellow background with a red cross superimposed [23.26].

[23.26] Low Rail Adhesion Site Termination Sign.
Area: All Areas   Usage: Low   Status: Current

Some locations on the London, Tilbury & Southend line are subject to rough riding at certain times of year because of expansion or contraction in the clay below the trackbed. Markers have been placed at the beginning and end of each affected area, to assist drivers in identifying the sites concerned. Since the underlying cause of the rough ride is known, occasions on which emergency speed restrictions need to be imposed are reduced. Each site has been assigned a unique number, which appears on the markers together with two triangles. The triangles point up on the commencement marker [23.27] and down on the termination marker [23.28].

[23.27] Clay Shrinkage Area Commencement Marker (e.g. site 2).
Area: LT&S line   Usage: Low   Status: Uncertain
[23.28] Clay Shrinkage Area Termination Marker (e.g. site 2).
Area: LT&S line   Usage: Low   Status: Uncertain