AAPPENDIX
SIZES OF WARNING SIGNS AND SITING DETAILS
| 1 | 2 | 3 | 4 |
|---|---|---|---|
| 85th percentile speed of private cars | Height of triangular warning signs 3 | Minimum clear visibility distance 4 | Distance of sign from hazard 5 |
| (mph) | (mm) | (m) | (m) |
| Up to 20 | 600 | 45 | 45 |
| 21 to 30 | 600 | 60 | 45 |
| 31 to 40 | 750 (600) | 60 | 45-110 |
| 41 to 50 | 900 (750)1 | 75 | 110-180 |
| 51 to 60 | 1200 (900)1 | 90 | 180-245 |
| Over 60 | 1200 (1500)2 | 105 (120)2 | 245-3052 |
NOTES
1. The smaller bracketed sizes shown in column 2 should be used only where special amenity considerations or physical constraints apply (see para 1.14). The minimum clear visibility distance specified in column 3 should not be reduced.
The 1500 mm size shown in column 2, and the largest visibility and siting distances in columns 3 and 4, should normally be used where the speed limit is 70 mph on dual three-lane or four-lane motorways or all-purpose roads with hard shoulders. In other circumstances the 1200 mm size should normally be used, with the 105 m minimum clear visibility distance (see paras 1.22 and 1.23) shown in column 3 and the siting distance (see paras 1.20 and 1.21) shown in column 4 (adjusted in accordance with Note 5 below). However, road safety considerations may require a larger size. The Regulations prescribe a 1500 mm size for most warning signs, which may be used on roads other than those described above.
3. The table below shows, in millimetres, the appropriate heights of the triangular warning signs and the diameters of regulatory signs that indicate the headroom of a bridge or other structure. For signs on the approach, the minimum clear visibility distance and the distance from the hazard shall be in accordance with the above table for all warning signs. The signs to diagram 530 and 530A when placed on the approach to a hazard are more likely to indicate an overhanging building or structure where the maximum size is 900 mm and 1200 mm respectively (see Appendix B) rather than to indicate a low bridge (see section 7).
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