Traffic Signs Manual/Chapter 4/2013/18
18.1 These plates are prescribed for use with many of the warning signs described in this chapter (see direction 21, items 35 to 37). However, many supplementary plates may incorporate distances, obviating the need for separate distance plates. These are diagrams 518, 519, 530.1, 543.1, 546, 547.1, 547.2, 547.4, 547.7, 547.8, 563, 563.1, 773 and 950.1. Diagrams 518 and 519 may also include the word "for" before the distance, and "for" and a distance may be added to diagrams 553.2, 554.3 and 558.2. The working drawings (see para 1.8) show the correct layouts.
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The indication of distance on these signs may be varied (see Appendix C). On diagram 573, the distance may be omitted. The direction of the arrow may be reversed
18.2 Diagram 570 is used to indicate the distance over which a hazard extends. Generally, if this is for more than two miles, the warning sign should be repeated at suitable intervals with the plate indicating the remaining distance to the end of the hazard. However, account should be taken of visual obstructions en-route e.g. a rock outcrop might hide sheep wandering onto the road, necessitating a sign at that point.
18.3 On motorways or other roads with grade separated junctions where the hazard might extend over a long distance, (e.g. wild animals) the warning sign with a plate to diagram 570 should be repeated after every access slip road, or, if this distance would be excessive, at intervals of approximately five miles. Each plate should show the distance remaining to the end of the hazard.
18.4 Diagram 572 indicates the distance ahead to a hazard. The caption below each diagram illustrated in this chapter specifies if a distance plate may be used (but see para 18.1). Where such a sign is sited at a distance from the hazard significantly different to that recommended in Appendix A, it should normally be supplemented with a distance plate (see also para 1.20).
18.5 Diagram 573 is placed in advance of a junction, indicating the distance along the road from that junction to the hazard. The distance is measured from the junction and not from the sign. The sign may be sited on a minor road approaching a junction if the hazard is on the major road. The direction of the arrow may be reversed.
18.6 The distance shown on all three plates may be varied with
(i) distances over 3 miles being expressed in miles to the nearest mile;
(ii) distances of ½ mile or more but less than 3 miles being expressed to the ¼ mile; and
(iii) distances of less than ½ mile being expressed in yards to the nearest 10 yards.
In no circumstances may metric distances be used.