D3.17.4 Where taper lengths or rearward visibility at temporary merges on entry slip roads are below those set out in TD 22 "Layout of grade separated junctions" (DMRB 6.2.1) for the prevailing traffic speed, consideration should be given to providing "GIVE WAY" signs to diagram 602. The associated markings to diagrams 1003 and 1023 should be used where practicable, though their use with signs to diagram 602 is not mandatory in temporary situations (see direction 17(2)). When deciding whether "GIVE WAY" signs are to be used, it should be borne in mind that there are possible hazards associated with the use of the signs in these situations. Drivers on the main carriageway will have little room for manoeuvre and allowing vehicles that have been stationary to move off onto a high-speed carriageway is potentially hazardous.
D3.17.5 Where a junction is within the works area and segregation of traffic by destination is required, the advance signs and those indicating a bifurcation of routes to different destinations should be designed in accordance with diagrams 7212, 7220, 7230 and 7233 and with the design guidance in Chapter 7 (Section 13).
D3.18SURFACE CONDITION
D3.18.1 As part of a temporary traffic management layout, there will be occasions when areas of carriageway that are not normally used are brought into operation. The adequacy of these temporary surfaces should be considered, in particular, bearing in mind the needs of motorcyclists and cyclists. In addition, the effect on traffic of the following should be taken into account:
- cross falls on chevron areas, gullies and channels,
- drain covers in hard shoulders and in central reservations at crossovers, clearances if traffic runs on edge strengthening (e.g. safety barrier, emergency telephone), and
- surface condition, the need to sweep the surface and skidding resistance.
Similarly the effect on carriageways of carrying unexpected traffic loads needs to be considered (e.g. drain covers on the hard shoulder may need to be strengthened).
D3.18.2 When narrow lanes are used as part of a traffic management layout, the reconfiguration of the carriageway may place the longitudinal joints or the original road stud bases within the new lanes and in some cases in line with the vehicle wheel tracks. Road stud bases, as well as the inserts and their reflectors, should be removed and the carriageway reinstated before introducing traffic to the narrow lane layout. |f stud bases are retained, drivers may take avoiding action and, in addition, the bases may be held to be unlawful because they are not fitted to statutorily prescribed road markings.
D3.18.3 The "TEMPORARY ROAD SURFACE" sign variant to diagram 7010.1 is used to warn drivers of an unfinished road surface, for example, when road surfaces are removed or reshaped by planing operations before being resurfaced. Particular attention should be given to the programming and contractual arrangements for planing and resurfacing works so as to reduce to a minimum the periods that elapse between these operations. All reasonable steps should be taken to reduce hazards in the periods when the planed lengths are used as temporary running surfaces. A longitudinal step of more than 50mm should always be marked by a line of cones.
D3.18.4 The "RAMP AHEAD" sign variant to diagram 7010.1 warns of a sudden change of road level which the driver is approaching, and should be sited not less than 30m before the ramp. It must always be used in conjunction with the "RAMP" sign to diagram 7013. These signs should also be specified when cable crossing
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