DUAL CARRIAGEWAY ROADS
Plan DZC7: Lead-in zone for a two-lane crossover
Guidance on the design of the crossover is given in Section D6.5.
Principles for the crossover are as follows:
- two "diversion of lanes onto the other carriageway" signs (7210) located on either side of the carriageway at the start of the crossover;
- coning to Detail E is used on the near side;
- coning to Detail F is used on the off side;
- if a buffer zone is present, the coning to Detail F on the off side is followed by cylinders and studs to Detail H (as shown); Detail K is used if narrow lanes are present; if a buffer lane is present, then the coning to Detail F is followed by coning to Detail C1;
- one "keep left/right" sign (610) at the start of the crossover; if this is placed in a closed lane, as opposed to a normally non-trafficked area such as the verge, a footway or a hard shoulder, then a "lane closed" barrier (7105) with a high intensity warning light should be added;
- one "lane closed" barrier (7105) with a high intensity warning light and a "keep left/right" sign (610) at the end of the crossover;
- one "lane closed" barrier (7105) with a high intensity warning light and a "keep left/right" sign (610) atthe end of each lane crossed; in this context the central reservation is equivalent to either one or two lanes crossed, depending on its width;
- white lining or temporary studs to Detail J used as road marking between lanes; and
- a temporary mandatory speed limit will be in place; signs to diagram 670 should be continued from the lane-change zone; for the spacing of speed limit repeater signs, see Table 3.4, Note 1.
No relaxations apply.
Where the hard shoulder is not used for a works entry, and works access signs are not in place, an additional Detail A should be placed at the start of the coning blocking the hard shoulder.
For dual carriageways without hard shoulders it may be appropriate for traffic to be in lanes 2 and 3 approaching the crossover in order to enable works access from lane 1.
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