Department of Transport

“ Safety fences do not consistently follow the line of the road edge; mounting reflectors on them is likely to mislead drivers as to the true position of the verge. The recommended method of delineating the road edge is to use edge of carriageway markings (incorporating raised ribs if appropriate) together with road studs. It may sometimes be appropriate to use markers on safety fences on sinuous mountain roads over short lengths, or at sharp bends, where separate posts may be inconvenient. ”

“ The Traffic Signs Manual not only explains in non-legal language the requirements of the Regulations and Directions but also advises on all aspects of signs and their uses including matters not covered in the Statutory Instrument. If all highway authorities follow this advice a reliable and uniform system of traffic signing will be ensured and this will benefit road users throughout the United Kingdom. ”

“ Signs need to be of a size appropriate to the prevailing traffic speed on the road on which they are used. On roads with a 30 mph speed limit, the smallest prescribed size of warning triangle (normally 600 mm) is usually adequate. On roads where speeds are higher, signs need to be larger. This enables them to be detected at a greater distance and ensures that drivers have sufficient time to recognise and assimilate the warning and take any necessary action before the hazard is met. The largest signs are for use on motorways or high-speed roads. ”

“ ILLUMINATION
1.35 On unlit roads, reflectorisation generally produces an adequate level of sign luminance in the illumination from a vehicle’s headlamps. In areas of street lighting, however, much higher levels of luminance are required to ensure that signs are always adequately conspicuous. Reflectorised materials cannot guarantee luminance levels comparable to those provided by direct lighting. Modern microprismatic materials achieve high luminances for many drivers in defined situations, but not for all drivers in all circumstances. ”

“ It is a waste of public money to provide signs and then to allow them to lose effectiveness by subsequent deterioration.
1.74 Signs become less effective not only when characters or colouring deteriorate, but also when dirty or damaged or displaced as a result of accidents or vandalism. Damaged or dirty signs discredit the highway authority and lessen road users' respect for the signs. A periodic inspection of signs should be made to ensure their early repair and/or replacement when necessary and after dark inspections should be made of illuminated or reflectorised signs. ”

“ Warning Signs explains the use of the warning signs prescribed by the Traffic Signs Regulations. It enables the correct sign to be used, and advises on the appropriate size and siting to ensure adequate warning of the hazard. ”

“ The sign should be used sparingly, as in general it should be for drivers to judge what speed to adopt. It is not easy to determine a standard safe speed to negotiate a bend; factors which influence this include radius of curvature, camber/superelevation, road surface condition and type of vehicle. The sign may be used where the road layout is such that a driver might be misled, eg at an exit from a high-speed road where significant slowing is required before negotiating a sharp bend. ”

“ When mounted on a post specially provided for the purpose, that part of the post which extends above ground level should be not less than 100 mm wide and may be:
(i) of any single colour, or
(ii) coloured black and white in alternate horizontal bands, each band being not less than 225 mm nor more than 350mm deep.
16.3 The black and white banded post enhances the conspicuity of the hazard marker. In rural areas or in areas where speeds are high, this type of post will generally be most suitable. ”

“ Variations in distance of up to 10% are generally permissible, but if an appreciably greater variation seems required other alternatives should first be investigated. Steps should be taken to deal with obstructions to the visibility of signs. Over-hanging trees and shrubs should be cut back and bus stops moved if necessary. Standing vehicles may have to be prohibited if the sign cannot be sited to be free from such obstruction.
1.55 Permanent features which cannot be altered such as bends, hill crests, narrow verges, buildings etc will necessitate the special siting of signs. ”

“ This is to ensure that drivers have the necessary time to respond to the warning. Appendix A sets out recommendations for the distance from the hazard at which a sign should be sited. If it is impracticable to place a sign within about 10% of the recommended distance, it should be sited further upstream of the hazard at the nearest practicable point. It may be appropriate to supplement it with a distance plate to diagram 572 (see section 18) . A sign should not normally be sited more than 10% closer than the recommended distance, as this would be unlikely to provide sufficient warning. ”

“ You are free to: copy, publish, distribute and transmit the Information; adapt the Information; exploit the Information commercially and non-commercially for example, by combining it with other Information, or by including it in your own product or application. ”

“ Dual carriageway situations are dealt with in para 4.6. Signs will not normally be needed if the narrowing does not result in the loss of a lane and involves a taper no more severe than indicated in table 4-1. However, signs should be provided regardless of the rate of taper where a lane is lost on a single carriageway road or where the reduction in width is so great that the centre line marking has to be omitted (see also para 4.4) . The "REDUCE SPEED NOW" plate (diagram 511) should be used if a significant speed reduction is advisable. ”

“ At sharp left-hand bends siting on the right may not only be appropriate but preferable.
1.45 The right-hand side siting of signs is sometimes appropriate where signs need to be erected on both sides of a carriageway on one way streets, for example the NO ENTRY sign is normally so duplicated and on high speed carriageway roads duplication of warning signs is recommended. Duplication of speed limit signs is a statutory requirement-see directions 8 and 9 in the Traffic Signs General Directions 2002. ”

“ Its use should be restricted to sites where numbers of slow-moving pedestrians are likely to cross a road other than at a Zebra or signalled crossing. This might be near sheltered housing or nursing homes, where drivers need to be reminded that a pedestrian in the road ahead might be frail or blind and need more time to cross than an able-bodied person would. ”

“ Where possible signs should be attached to adjacent walls, so that they are not more than 2 metres from the edge of the carriageway, or be grouped on posts in accordance with paragraphs 1.62–1.68. Certain signs with small letters, e.g. plates for waiting restrictions, must always be mounted close to the edge of the carriageway. When posts must be erected in narrow footways they should be positioned to cause the least possible obstruction and should not reduce the clear walkway width to less than 1.0 metre. ”

“ A backing board must not itself be provided with a border, nor give the impression of being an additional border. Where it seems that a sign is not being noticed by drivers, it should be checked to ensure that it is well-sited, not obscured by foliage or other obstructions, and is of the appropriate size and in good condition. Only then should the use of a yellow backing board be considered.
1.33 A yellow backing board may be reflectorised to increase its conspicuity at night. ”

“ For the 600mm and 750 mm size triangles, the smaller x-height, where more than one is shown, is appropriate if the 85th percentile speed is 20 mph or less. Where a 50 mm x-height is marked with an asterisk, this is the standard size for 85th percentile speeds up to 30 mph. For the 1200 mm size triangle, the larger x-height, where more than one is shown, should be used on dual carriageway roads where the national speed limit applies or on single carriageway roads where greater emphasis is required. ”

“ More details of these alphabets are given in Chapter 7.
1.35 In addition to distinctive shapes, different classes of signs have distinctive colour combinations. The number of different colours which can be usefully used on signs is limited by both aesthetic and technical requirements; Appendix 1 lists the colours with their specifications. Subsequent chapters describe their use in detail.
1.36 With standardisation of types of signs, there must also be uniformity in the use, siting, mounting height, illumination and reflectorisation of signs within limitations imposed by site conditions. ”

“ The direction of the arrow may be reversed
10.15 A cattle grid on a public road should always be preceded by the cattle grid warning sign to diagram 552, as it might otherwise catch drivers unawares. Grids are especially hazardous for two-wheeled traffic. Signs should normally be sited at the standard distances set out in Appendix A. The plate to diagram 553 indicating the direction of the by-pass for horse-drawn vehicles or accompanied animals can accompany the sign it the entrance to the by-pass is reasonably close to the grid. ”

“ The problem can occur even when there is more than one lane. At times of light traffic flow, a vehicle being driven in the left hand lane at 70 mph might close unexpectedly rapidly on a slow-moving lorry, or on a queue of vehicles waiting to pass it. ”

“ Mounting heights
1.49 Where possible the lower edge of the sign should be between 900mm and 1500mm above the highest point of the carriageway alongside. The higher mounting should be used where excessive spray is likely to soil the signs. In built up areas signs may have to be higher for various reasons where they are erected on footways and transverse to them they must obviously allow sufficient clearance for pedestrians: 2100mm is the absolute minimum recommended but 2300mm is preferable. ”

“ Signs located where they are subject to heavy soiling from passing traffic, or algae growth (a common problem with signs beneath tree canopies) will need more frequent cleaning. Neglect reduces the external contrast between the sign and its surroundings, making it less likely to be noticed by drivers. It also reduces the internal contrast between legend and sign background, making the sign more difficult to read. Moreover, it seriously reduces light transmission through the retroreflective medium. Dirty signs will be far less effective at night. Older drivers are particularly disadvantaged ”

“ This problem in dealing with information overload increases with age, so that older drivers suffer disproportionately. Generally, therefore, not more than two signs should be mounted on one post. When a sign is accompanied by a supplementary plate, the combination of sign and plate should be regarded as one sign for this purpose. Exceptionally, three signs may be mounted on one post provided none requires a supplementary plate.
1.28 Warning signs should not be mounted on the same post as a STOP or GIVE WAY or terminal speed limit sign, nor mounted on a traffic signal post. ”

“ On two-lane carriageways subject to a 30 mph speed limit, a single sign mounted on the side of the road on which the lane is to be lost may be adequate, although the possibility of obscuration by parked vehicles should be considered. Also all-purpose dual three-lane carriageway roads subject to a 70 mph speed limit. ”