Traffic Signs Manual/Chapter 4/2013/20

by Department of Transport (UK)

20SLOW-MOVING VEHICLES

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MILITARY VEHICLES

May be used with diagram 570

20.1 The sign to diagram 582 may be used at locations where military vehicles are expected either to cross the road ahead or to be moving at low speed along the road. If the vehicles have regular entry and exit points along the road, distance plates may be appropriate (see section 18).

20.2 The sign is not restricted to warning of tanks; it may be used for any military vehicles which are either larger than might normally be expected along that type of road, or travel at reduced speed.

SLOW LORRIES

May be used only in combination with diagram 583.7

May be used only in combination with diagram 583.
The distance may be varied (see Appendix C)

20.3 The slow-moving vehicles signs, diagrams 583 and 583.1, are intended for use on roads where the gradient is such as to have an adverse effect on the speed of heavy commercial vehicles, thereby causing a potential hazard to other vehicles in the same lane. This is not simply a question of congestion. The problem can occur even when there is more than one lane. At times of light traffic flow, a vehicle being driven in the left hand lane at 70 mph might close unexpectedly rapidly on a slow-moving lorry, or on a queue of vehicles waiting to pass it.

20.4 The criteria for using these signs will differ from the criteria for normal steep hill signs because they are aimed at drivers following the slow vehicle and not at the driver of the slow vehicle itself. In addition to the gradient of the hill, consideration should be

given to the length of the hill and the differential speed of heavy and other traffic. They are most likely to be of use on motorways and high-speed dual carriageway roads with substandard gradients. The sign should be used for uphill traffic only; the "steep hill" signs in section 6 should be used in the downhill direction.

QUEUES LIKELY

May be used only in combination with diagram 584.1

May be used only in combination with diagram 584.
An arrow may be added to the sign. "Queues likely" may be varied to "Queues likely on slip road"

20.5 Drivers should expect to meet queues on the approaches to roundabouts or traffic signals, where adequate advance warning can usually be given using signs to diagram 510 (see paras 2.13 to 2.18) or 543 (see section 8) as appropriate. The "Queues likely” signs, diagrams 584 and 584.1, are intended for use where drivers might unexpectedly come across a queue, e.g. around a bend or over the brow of a hill. These signs should be used only where there is a persistent problem, causing a significant hazard, despite the presence of the standard warning signs and are not appropriate as a general warning of congestion. They should be sited sufficiently far in advance of the obstruction to the sight line to enable drivers to stop in time. Distance plates must not be used.

20.6 Where the queue is likely to be in a road that leads from a junction ahead, the "Queues likely" plate may incorporate an arrow pointing to the left or to the right as appropriate. Details are shown on the working drawing (see para 1.8).

20.7 The sign may also be used on motorways or other high-speed dual carriageway roads with grade separated junctions where queues on an exit slip road regularly extend back onto the main carriageway. Where queues on the slip road effectively shorten the deceleration length available, but do not usually extend onto the main through carriageway, the variant "Queues likely on slip road" should be used. Care should be taken to ensure that the assembly does not obstruct the driver's view of existing signs.