Page:UK Traffic Signs Manual - Chapter 8 - Part 2- Traffic Safety Measures and Signs for Road Works and Temporary Situations) - Operations 2009.pdf/112



The Mobile Lane Closure (MLC) technique for use on dual carriageway trunk roads uses essentially the same signs, although fewer, as those employed for a static closure.

The intervals between the signs are changed to concentrate the warning information presented to passing drivers by ensuring that they may see, at any instant, at least two consecutive signs. To improve the signs’ conspicuity, and also to compensate for their reduced number, the prescribed design incorporates a yellow sign display board and high-intensity flashing amber lanterns are mounted at each corner.

All MLC operations on motorways and other dual carriageway roads should comply with the following guidance and fully take into account the advice relating to the design of the technique given in Part 1: Design, Section D6.26. Operational aspects are dealt with in this section and are illustrated in Plans MLC1 to MLC7 below. Note that single vehicle works are dealt with in Section O8.

Working through junctions using the technique requires particular care. For this reason, and because of restricted sight lines, its use on roads of an urban nature or with a speed limit of 40 mph or less will probably be limited and would require a detailed risk assessment. In these situations, the use of single vehicle works may be more appropriate. See Section O8.

The MLC technique should be carried out in good visibility, during periods of low risk when traffic flows are low and congestion is unlikely to occur. The maximum allowable traffic flows when the MLC technique may be operated are given in Table 10.1 in Section O10.4.

MLC working on dual carriageway roads without a hard shoulder requires additional planning. Advance signing requirements and placement positions should be carefully planned, allowing for any particular circumstances which dictate the need for additional signs. See Plan MLC1 in Section }}.

Use of the MLC technique on four to six-lane dual carriageway roads requires special care and the use of additional advance sign vehicles as appropriate to the prevailing operational conditions is recommended. Work on five and six-lane dual carriageway roads in particular should only be undertaken by the most experienced MLC teams. The MLC technique should not be used on five or six-lane dual carriageway roads unless matrix and/or VMS signals are employed (see Section O10.5) in conjunction with a light arrow sign. See Section O10.8.

This technique should only be carried out where there is adequate stopping sight distance as specified in Departmental Standard TD 9 "Highway link design" (DMRB 6.1.1). For most dual carriageway roads, the desirable minimum visibility requirement is a stopping sight distance of 295 metres.

Conditions which reduce visibility such as spray from wet roads, rain, fog etc., increase the risk of accidents. The technique should not be operated when drivers approaching the works are heading towards a sun low on the horizon. MLCs should therefore not be used if visibility has been reduced to below an acceptable level.

When working in the vicinity of junctions or roundabouts where approaching vehicles are not able to see the rear-mounted signing, or rear illumination as required in paragraph O10.1.2 is ineffective due to the angle of approach, the works and/or signing vehicles should have their flashing amber warning beacons switched on and approach signing to the junction placed as appropriate.

All equipment should be checked to be in full working order prior to starting MLC operations. 110