Page:UK Traffic Signs Manual - Chapter 8 - Part 2- Traffic Safety Measures and Signs for Road Works and Temporary Situations) - Operations 2009.pdf/107

 On single carriageway roads, vehicles joining from the side road should be directed to join the tail of a convoy travelling in the direction in which they wish to turn. If the traffic flow on the side road is likely to be high enough that difficulties may be encountered with this procedure, then the advice given in paragraph O9.8.5 below should be followed.

For a minor road with high flows, if a suitable diversion exists for the minor road traffic, a road closure should be implemented to close it in the vicinity of the junction. If there is no diversionary route, if possible the works should be located so that the junction falls beyond the section of road subject to convoy working and signal control should be provided for the minor road flow. In the case where this is not possible, it may be necessary to consider the use of a convoy vehicle for the side road traffic to avoid unescorted traffic travelling through the works. See also paragraph O9.8.3 above.

Arrangements at all locations which involve side roads within a work site should minimise the possibility of a gap being created between the end of the convoy and the traffic joining it from the side road.

A system of monitoring queue lengths should be implemented so that any excessive build-up of traffic can be identified at an early enough stage to enable action to be taken to avoid long delays. If unacceptably large queues of traffic occur, it may be necessary, where practicable, to suspend convoy working in order to clear the delay.

If convoy working is suspended, the 10 mph signing should be replaced with 30 or 40 mph signing and the works will need to be suspended or modified so that the appropriate safety zone can be implemented. A 30 mph restriction would be applicable if this is the permanent limit prevailing on the road. A 40 mph limit would apply where the permanent limit exceeds 30 mph. Once the queue has cleared, then normal 10 mph convoy operations may be recommenced. It should be borne in mind that, depending on the nature of the works, it may take longer to implement these measures on some schemes than on others.

On sites where it is not possible to establish a safety zone, plant and operatives shall be stood down and moved to the back of the working space until convoy working has been re-established.

The works supervisor should confirm to the traffic control supervisor that the running lane is clear before unrestricted traffic is allowed past the works.

Contingency measures should be pre-planned to allow the free passage of emergency vehicles through the convoy lane. This should include discussion with the local emergency services, where possible, during contract preparation. One method is for a single radio call to instigate the suspension of work and the implementation of an all-red (or all-stop) stage, thereby clearing the running lane and enabling emergency vehicles to overtake the waiting queue on the off side, “jump” the signals (or manually operated "STOP/GO" board) and proceed unobstructed through the works.

Before the emergency vehicle enters the site, the traffic control supervisor should ensure that any convoy travelling in the opposite direction to it has cleared the works or has been halted at a location where the emergency vehicle can pass. He should also obtain confirmation from the works supervisor that the running lane is clear and that plant and operatives have been stood down. 105