Plan DZB7: Lane-change zone for a two-lane closure (direct taper) on a dual carriageway road for which the national speed limit applies
Four pairs of advanced lane closure signs are required:
- wicket signs indicating the closed lane (7202) with distance panel "800 yards" (7208) on the near side and off side, placed 800m in advance of the works. These signs are repeated, with the appropriate distance plate, at 200 yard intervals to a point 200 yards in advance of the works, i.e. at 600 m, 400m and 200 m, and
- on dual carriageway roads of five lanes or more when the works require closure of the near side lane(s), subject to certain flow limits (see paragraph D6.13.11), the wicket signs indicating the closed lane (7202) on the off side of the carriageway may be omitted.
Where a temporary mandatory speed limit is in place, one pair of temporary speed limit signs is required, followed by repeater signs:
- the temporary speed limit sign (670), which will generally be 50mph, is to be placed on the near side and on the central reservation 50m in advance of the first sign indicating lane closures or restrictions (e.g. signs to diagram 7201, 7202, 7201.1), and
- for a temporary speed limit of 50mph the distance between successive signs on the same side of the carriageway should not exceed 700m, with a maximum of 450m between consecutive repeater signs on alternate sides of the carriageway. For temporary mandatory speed limits of
40mph or less, see Table 3.4, Note 1.
For entry taper details, including relaxations, see Plan DZB8.
Signing to Detail A is located on the hard shoulder opposite the "keep left/right" sign (610) at the start of the taper and opposite the "lane closed" barrier (7105) and "keep left/right” sign (610) at the end of each closed lane.
A direct lane closure of near side lanes 1 and 2 on a three or more lane dual carriageway road is permitted at low traffic flows. For a definition of "low traffic flows", see Glossary (Appendix 2).
For works for which relaxations apply, the size of signs to diagram 7202 in the left-hand side of the carriageway should be as given in Tables A1.1 and #table1.2|A1.2 (Appendix 1) but the signs on the central reservation may be reduced to 1350mm. The x-height on the supplementary plate to diagram 7208 should be reduced proportionally.
180
