D6.17LEAD-IN ZONE
D6.17.1 The lead-in zone starts at the point at which all lane changes, if required, should have been completed and continues to the beginning of the longitudinal safety zone.
D6.17.2 List of plans:
Plan DZC1 Lead-in zone for a single-lane changeover on a dual carriageway road with a permanent speed limit of 40 mph or less
Plan DZC2 Lead-in zone for a single-lane changeover on a high-speed dual carriageway road
Plan DZC3 Lead-in zone for a two-lane changeover
Plan DZC4 Lead-in zone for a single-lane changeover onto the hard shoulder
Plan DZC5 Lead-in zone for a two-lane changeover with narrow lanes using the hard shoulder
Plan DZC6 Lead-in zone for a single-lane crossover
Plan DZC7 Lead-in zone for a two-lane crossover
Plan DZC8 Lead-in zone for a three-lane crossover with narrow lanes
Plan DZC9 Lead-in zone for splitting lanes for a changeover onto the hard shoulder and a single-lane crossover
PRINCIPLES OF DESIGN FOR THE LEAD-IN ZONE
Plan DZC1: Lead-in zone for a single-lane changeover on a dual carriageway road with a permanent speed limit of 40mph or less
Guidance on the design of the changeover is given in Section D6.6.
Principles for the guide island are:
- coning to Detail F is used to guide traffic past the island — if existing carriageway markings are suitably located and in good condition then Detail C1 may be used, and
- the length of the guide island, excluding tapers, is 100 m.
Principles for the guide island for which relaxations apply are as for standard works except:
- coning to Detail C1 is used to guide traffic past the island.
Principles for the changeover are:
- straight “taper” or smooth ’5’ shaped curve layout; length of changeover as detailed in Table 6.6,
- coning to 9 m spacing either side of the changeover (Detail C1 — see Table A1.5 (Appendix 1));
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