Page:UK Traffic Signs Manual - Chapter 8 - Part 2- Traffic Safety Measures and Signs for Road Works and Temporary Situations) - Operations 2009.pdf/124

MOBILE LANE CLOSURE TECHNIQUE If the working vehicle has to stop for more than a few seconds the driver should inform the supervisor, who will stop the remainder of the convoy until informed by the driver of the working vehicle that it is mobile again.

Where there is a hard shoulder with a discontinuity of up to 400 m, the working vehicles and block vehicles should proceed together and advise the rest of the mobile train of their position. When the leading warning vehicle reaches the discontinuity, all warning vehicles should stop. The leading warning vehicle should proceed on its own to regain the hard shoulder after the discontinuity, when the rearmost block vehicle is about 100 m past its far end. If the train is slow-moving, this distance will need to be increased to ensure the leading warning vehicle does not catch the train up and reduce the actual distance between itself and the block vehicle to less than the 200 yards figure indicated on its distance plate. The following warning vehicles should then negotiate the discontinuity in turn in a similar manner, although maintaining station with the leading warning vehicle while negotiating the discontinuity is temporarily less important. Work on reduced width sections exceeding 400 m should be carried out by means of a lane closure using static signs and cones.

On particular stretches of dual carriageway, it may be necessary to reduce the distance between advance warning vehicles to ensure that the next vehicle in the convoy can be seen by road users before they have passed the preceding one. Drivers should be instructed to make this temporary adjustment as necessary.

The supervisor should arrange for periodic traffic counts to be made – normally a three-minute count every 15 minutes to ensure that the flow remains less than the value determined as appropriate during the planning of the work. The figures in Table 10.1 in Section 10.4 are absolute maxima and appropriate flow values may well be lower depending on the particular features of the site.

The closure should not be taken off simply on the grounds of traffic flow levels until either of the following occurs:
 * two successive counts give results above the appropriate value; or
 * the counts show a rising trend with the last one above the appropriate value.

If for any reason the supervisor considers that the situation is dangerous, he should abort the operation.

As the MLC approaches a junction the supervisor should instruct team members by radio on the procedure to be adopted. This will depend on the nature of the works being undertaken, the nature of the junction, and the volume of traffic on both the subject road and the joining road. When the MLC is operating on the near side lanes of the main carriageway, consideration shall be given to temporarily closing the slip road whilst the convoy passes it. This may be achieved with the assistance of either the police or a traffic officer if available.

Alternatively, if the slip road is not closed, static road works ahead sign to diagram 7001 displaying a "Mobile road works" plate to diagram 7001.1, or a mobile sign to diagram 7402 displaying an "Ahead" plate, should be displayed to joining traffic just prior to the arrival of the convoy, and removed after it has passed. See Part 1: Design, Section D6.26.

The driver of each vehicle should exercise special care when negotiating the junction. 122