Page:UK Traffic Signs Manual Chapter 1 (1982 amended to 2004).pdf/16



1.39 There are four aspects to the positioning of a traffic sign:

(i) Its siting along the road in relation to the junction, hazard, or other feature to which it applies.

(ii) Its placement in relation to the edge of the carriageway and other features of the cross section.

(iii) Its height above the road and

(iv) Its orientation.

(i) Siting

1.40 In order to allow a driver adequate time to comply safely with its message each sign should be sited at the correct distance before the site to which it relates. This distance will generally depend on the speed value of the road.

1.41 Because signs are designed for the legends to be recognisable and legible from distances depending on their type and the road speed, it is obviously essential to ensure that the signs are in fact visible from these distances and not obscured by intervening obstructions.

1.42 In subsequent chapters details are given of such siting and visibility distances.

1.43 Drivers are accustomed to signs being on the left-hand side and such positioning should be the general practice.

1.44 However, siting on the righthand side is appropriate in certain circumstances. For example where there are difficulties in siting on the left, or when worthwhile economies are to be gained such as at T junctions where one sign facing both ways will suffice instead of a sign on the left for each approach. 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.

1.46 Other methods of siting are sometimes required. For instance signs are usually placed on the far side of the head of the T junction for drivers approaching on the stem. At underpasses overhead signs may be more appropriate. Signs on roundabouts and refuges are also specially sited.

1.47 More guidance is given on detailed siting in the relevant parts of subsequent chapters.

(ii) Placement

1.48 Signs should be set at least 450mm from the edge of the carriageway. This should be increased to 600mm where there is a severe camber or crossfall and where signs are mounted on the central reserve of dual carriageways. On high-speed dual carriageway roads the clearance should be at least 1200mm and where there is a hardened verge the nearest edge of the sign should be not less than 600mm behind the edge of the hardening.

(iii) 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.

1.50 If signs are to be illuminated externally by their own lamps and vandalism is likely, the signs must be sufficiently high for the lamps to be out of easy reach.

(iv) Orientation

1.51 In rural areas specular reflection from traffic signs can be troublesome. To eliminate or minimise its effect, signs should be set at angles so as to face slightly away from the beam direction of headlights from approaching vehicles within a distance of 200 metres.