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May be used with diagram 57 7, 573.7 or 572
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May be used only in combination with diagram 504.7, 505.7, 506.7, 507.7, 570, 572, 572.7, 572.2, 573, 576, 577, 520, 523.7, 524.7, 528 or 556
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A distance in yards to the nearest 70 yards may be added before, or substituted for the word "AHEAD"
ROUNDABOUTS
2.13 The sign to diagram 510 may be used to indicate the approach to a roundabout where adequate warning is not conveyed by a map-type advance direction sign. It may be used with a supplementary plate to diagram 511, 513.1 or 572. The roundabout warning sign should be used only for true roundabouts. It should not be used to give advance warning of a gyratory system or where the approach to an otherwise standard roundabout is controlled by signals (see paras 8.4 and 8.5).
2.14 On high standard all-purpose dual carriageway roads subject to a speed limit of 70 mph, diagram 510 should be used in addition to the map-type advance direction sign and be supplemented by a plate to diagram 511 "REDUCE SPEED NOW". One sign and plate should be situated on the central reservation 500m in advance of the roundabout, with a duplicate on the left side 450 m in advance (see also paras 5.7 and 5.13).
2.15 Where a roundabout on such a road follows a series of grade separated junctions, the signing described in para 2.14 should be supplemented by an additional sign to diagram 510 on each side of the carriageway, plated with diagram 572 "½ mile". On other roads, where accidents result from excessive approach speeds, signs to diagram 510 should be sited in accordance with the recommendations in Appendix A.
2.16 At mini-roundabouts, a roundabout warning sign should be provided if the clear visibility distance (see para 1.23) of the sign to diagram 611.1 is less than indicated in the relevant sections of table 2-1 and the junction is not preceded by an advance direction sign to diagrams 2024, 2119 or 2120 depicting the roundabout.
2.17 The "REDUCE SPEED NOW" plate may be used with the diagrams detailed, where it is considered that a warning sign alone might not result in a sufficient reduction of speed to enable the hazard to be negotiated in safety.
2.18 Where further emphasis is needed on high-speed approaches on dual carriageway roads, the countdown markers to diagrams 823, 824 and 825 may be used, sited 300, 200 and 100 yards respectively from the give way line. The background colour must be changed to green when used on a primary route, and white (with black symbols and border) on a non-primary route. The signs should normally be mounted in pairs on each side of the carriageway, with the signs on the central reservation being reversed so that the bars incline downwards to the left.
2.19 The sign to diagram 7014 with the legend "NEW ROUNDABOUT AHEAD" (see para 1.17 for guidance on size) may be erected to warn of a new roundabout. Its use is restricted to a period of not more than 3 months from completion of the works (direction 37), after which it must be removed.
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