Page:UK Traffic Signs Manual - Chapter 8 - Part 2- Traffic Safety Measures and Signs for Road Works and Temporary Situations) - Operations 2009.pdf/114

MOBILE LANE CLOSURE TECHNIQUE Any external works sub-contractor should be competent and should attend a briefing to familiarise themselves with the operation of the MLC technique.

Operatives should be assessed to ensure that they are fit and have no physical impediments which would prevent them from safely carrying out their MLC operational duties, and if appropriate, their suitability for working at night; see also Section O6.

A relief driver may be employed in the leading (working) vehicle to give directions during complicated manoeuvres. The relief driver should be fully qualified and trained and be capable of replacing any other mobile sign vehicle driver in the convoy should it become necessary.

All those working on the road must wear high visibility clothing (see Section O6.3) and comply with all of the safety measures identified in the risk assessment; see Section O2.2.

The use of MLC techniques on dual carriageway roads is restricted by certain traffic volume parameters; see Table 10.1 below.

When working past slip roads the maximum flow on the slip road should not exceed 500 vehicles per hour without police or traffic officer assistance with traffic control.

Table 10.1 gives absolute maximum flows for MLC operations which relate to level and well-aligned sites with hard shoulders. These figures may need to be reduced for sites on roads with steeper than normal gradients, difficult horizontal alignments (in particular, left-hand bends) or roads lacking an adequate hard shoulder.

Traffic volume parameters in Table 10.1 are given in terms of vehicles without regard to traffic composition. Typically, traffic on these major roads will include 15-20% of heavy goods vehicles. Any markedly higher or lower proportion of heavy goods vehicles will affect the capacity of the layout and the tabulated figures should be amended accordingly. e.g. if the heavy goods vehicle content is 30% the vehicle flow levels should be reduced by 10%.

Providing adequate care is taken, it is considered that, in general, the flow figures in Table 10.1 apply equally to day and night-time mobile works.

The flow limit figures given in Table 10.1 have been derived on the basis that they are within the traffic capacity of the lanes remaining open and therefore at these flows queues are unlikely to form. The table does not specifically consider separate limits for establishing and removing a mobile lane closure. Consideration of how and when a closure can be set out and removed should form part of the overall planning of the work when deciding on a safe method of working. The specific decision on whether or not to move MLC vehicles into/out of position will depend on the appearance of acceptable gaps in the traffic flow. 112