Page:UK Traffic Signs Manual - Chapter 4 - Warning Signs. 2013.pdf/15



Diagram 512 should be used to give advance warning of a bend which a driver might find difficult to negotiate without slowing down and the severity of which cannot easily be seen either by day or by night. The symbol should indicate a bend to the left or right as appropriate. The degree of danger at a bend varies mainly with four factors–the speed of approach, the radius of curvature, the superelevation and the skid resistance of the road surface. No uniform objective test can be applied and traffic authorities must rely on a subjective assessment of these factors when deciding whether to use the sign.

The radius of curvature not only affects the safe speed appropriate to the bend, it might also reduce forward visibility so that drivers need to slow down.

The sign should be used sparingly and only to indicate a bend hazard. It should not be used simply to allay local apprehension regarding the speed of traffic. Over-use of the sign could eventually compromise its contribution to road safety.

On high standard all-purpose dual carriageway roads, the signs should be erected in advance of any bend of radius less than 450 metres.

Edge of carriageway markings may be used with this sign. It might also be appropriate to change the centre line to a warning line. Chapter 5 gives further guidance on the use of these markings.

Where junctions which warrant signing in accordance with para 2.2 occur on sharp bends, use of diagrams 512.1 or 512.2 avoids the need for separate signs.

The sign to diagram 513 should be used only where bends of similar severity follow in close proximity. The symbol must be reversed where the first bend is to the right, drivers are likely to be misled if it is in the opposite direction to that indicated. The sign should be used only when the distance between the bends is less than that given in table 3-1. See Appendix A for further guidance on the size and siting of warning signs.

The distance plate (diagram 570, see section 18) should be used where a series of bends follow each other at distance intervals less than those referred to in the table. Where a double bend sign is used with a distance plate, bends or combinations of bends 14