D7CONVOY WORKING
D7.1GENERAL
D7.1.1 Where normal traffic management arrangements are not feasible because of restricted highway width, and diversion is impracticable, a method of convoy traffic management may be used. In this method, traffic is brought to a halt in advance of road works and is then led slowly in single file through the site past the works by an appropriately signed works vehicle.
D7.1.2 This method of convoy traffic management shall not be used on motorways.
D7.1.3 It is essential with little or no safety zone clearance that traffic speeds past the working space must be reliably reduced to 10mph or less, and an agreed safe method of working imposed on the site.
D7.1.4 Convoy working may be used during the hours of daylight or darkness and can be used on:
- single carriageway roads where traffic travels either in a single direction, or in alternating opposite directions,
- individual carriageways of two-lane all-purpose dual carriageway roads where traffic travels in one direction only and works have reduced the traffic to single file; and
- carriageways during surface dressing operations when it is considered necessary to ensure compliance with speed limits which have been implemented to protect newly-laid surface dressing.
D7.2TRAFFIC FLOWS
D7.2.1 Convoy working can be used successfully on single carriageway roads with two-way peak hour flows of 900-1000 vehicles/hour. However, at these flow levels it may be necessary to restrict peak time working or make provision to withdraw convoy traffic management periodically to disperse queues. In this event the work activity must also be suspended until the passing speed of traffic can again be reduced to 10mph or less and convoy traffic management reinstalled.
D7.2.2 On dual carriageway roads, convoy traffic management can be used successfully where the one-way hourly traffic flow does not exceed 600 vehicles/hour.
D7.3PLANNING
D7.3.1 For general planning of the works refer to Section D2.
D7.3.2 The pre-planning should include:
- planning the works and individual operations to minimise their possible effect on traffic delay and interference with the convoy system; if applicable, provision for pedestrians should also be considered,
- arranging the works to avoid junctions occurring within the convoy site,
- planning an appropriate convoy system, which will ensure that the speed of all traffic passing the works is reliably reduced to 10mph or less,
- determining a queue management strategy including levels of congestion which trigger special action, and safe methods of working for the withdrawal of convoy working,
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