Page:UK Traffic Signs Manual - Chapter 8 - Part 2- Traffic Safety Measures and Signs for Road Works and Temporary Situations) - Operations 2009.pdf/105



Signals should be operated manually during operation of convoy working with provision to switch to vehicle-actuation during periods when no work is taking place. Manually operated "STOP/GO" boards can be beneficial on single-vehicle convoy working since they are more sensitive to traffic demand and allow more control of "red light" jumping which can be more prevalent with convoy working. However, it is unlawful to use "STOP/GO" boards during hours of darkness unless they are directly lit. See also Sections O3.21 and O3.22.

Where possible the period between convoys in the same direction should not be more than five minutes. Shorter periods would be preferable but are not always practicable. The optimum length of convoy and cycle time for the site layout and traffic flows should be calculated as far as is possible before operations commence. Transportation of chippings etc. should be planned to work in behind or between convoy flows.

As soon as a convoy has passed the signals (or manually operated "STOP/GO" board), the vehicle that is to lead the next convoy should take up position to prevent any traffic entering the restricted lane. This is not possible when only one convoy vehicle is in use. In this case, traffic control should be by means of individually manned "STOP/GO" boards so that operatives are present to encourage drivers to obey the signs and travel in convoy. Should a gap occur for any reason in the traffic passing the signal (or manually operated "STOP/GO" board) then the operator should immediately signal "STOP". This is to prevent a "late" vehicle rushing through the convoy lane to catch the tail of the convoy.

At the end of the works, the position at which the convoy vehicle pulls over and waves traffic on should be such that the last vehicle in the convoy has passed the works. This will avoid the tail of the convoy speeding up whilst still passing the work area.

It is important that the arrangements for imposition of mandatory limits are discussed and agreed with the police and Highway Authority.

The issues relating to the correct application of temporary mandatory speed limits (including signing) are dealt with in Part 1: Design, Section D3.7.

A Highway Authority may issue an Order or Notice under section 14 of the. Others may seek an Order under section 84 of the Act.

The signing required is shown in Plans CW1 and CW2 in Part 1: Design, Section D7.6. Repeater speed limit signs should be placed throughout the works site at 200 m intervals on alternate sides of the road.

A temporary mandatory 10 mph limit should be imposed throughout the length of the works which are subject to convoy working. This should extend a short distance beyond the works so that the tail of the convoy is held to 10 mph or less until it has passed the works. Generally an extension of the coned section will be necessary to prevent overtaking of the convoy vehicle.

Appropriate speed limit signs must also be displayed to traffic entering from a slip road or side road within the section where the speed limit is imposed.

On high-speed roads, both single and dual, a temporary mandatory limit of 20 mph below the permanent limit prevailing on the road should be imposed in advance of the temporary 10 mph limit. The speed limit signs should be positioned far enough away from the works to permit traffic to reduce its speed comfortably to the required level, but not so far as to prematurely constrain drivers to artificially low speeds for long distances in advance of them. 103