5TWO-WAY TRAFFIC AND DUAL CARRIAGEWAY ROADS
TWO-WAY TRAFFIC
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May be used With diagram 577 578 or 572
5.1 The signs to diagrams 520 and 521 indicate the resumption of two-way traffic on a single carriageway road after a length of dual carriageway and, in the case of diagram 521, after a one-way road. The sign to diagram 522 indicates a two-way road crossing ahead (see para 5.4).
5.2 Pairs of opposing arrows to diagram 1038, indicating the ahead direction, may be used to supplement the sign to diagram 521. This may be particularly helpful where a single carriageway road is similar in appearance to one carriageway of a dual carriageway road.
END OF ONE-WAY ROAD
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May be used with diagram 570 or 572
5.3 Diagram 521 should be used to indicate a change from one to two-way traffic, and also at the commencement of any two-way side roads that form a junction with a one-way road. It should be erected as close as possible to the beginning of two-way working, consistent with being readily visible to turning traffic, and may be repeated after 100 metres.
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May be used with diagram 572
5.4 Diagram 522 is generally used on a one-way road to indicate that a road it joins or one that crosses it carries two-way traffic. It is normally sited on the back of the "no entry" sign. However, it might also be helpful on a two-way road where it is crossed by another two-way road after a succession of intersections with one-way roads.
END OF DUAL CARRIAGEWAY
5.5 The road markings required where a dual carriageway road reduces to a single carriageway are detailed in Chapter 5. Table 5-1 below lists the appropriate tapers. Figure 5-1 illustrates the signs and markings needed in a built-up area where speeds are relatively low. The sign to diagram 520 should be Table 5.1 sited in advance of the end of the dual carriageway at the usual distance appropriate to warning signs (see Appendix A). The sign to diagram 521 should be (mph) erected at or as near as possible to the beginning of two-way working, and may be repeated after 100 metres.
| 85th percentile Speed (mph) |
Taper |
|---|---|
| Up to 40 | 1 in 40 |
| 41 to 50 | 1 in 45 |
| 51 to 60 | 1 in 50 |
| Over 60 | 1 in 55 |
5.6 Where traffic speeds are high, as on inter-urban roads, more comprehensive signing as in figure 5-2 should be provided.
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