Page:UK Traffic Signs Manual - Chapter 8 - Part 2- Traffic Safety Measures and Signs for Road Works and Temporary Situations) - Operations 2009.pdf/118

MOBILE LANE CLOSURE TECHNIQUE Adequate means should be provided to support the sign display boards, bearing in mind the possible operating speeds. The lower edge of every sign display board when mounted on a vehicle should be at least 0.75 m above the road surface. When fitting a sign display board to a vehicle, the vehicle’s rear lights, reflectors and number plate must not be obscured.

Signs shall be removed from the view of following drivers when not in use. If a blind is used it should be opaque and preferably yellow, and should fully reveal or fully cover the sign. When visible to other road users, the "keep left/right" sign must not be rotated to a vertical position.

Flap type variable message signs should be constructed to facilitate opening/closing by a person standing in a safe position. They should be fitted with a means of securing them in both the open and closed positions. The construction and colouring of these signs should be such that the appearance of the sign is not compromised regardless of whether the flaps are up or down. Particular attention should be given to the flap hinge detail in this respect.

On lane closure signs, each arrow symbol should be capable of being flapped to show a red bar symbol as an alternative to the arrow. Each flap should be fitted with a means of securing it in either of these positions. The red bars must be at the correct height otherwise the legibility of the lane closed symbol is affected, especially at night, making it difficult to distinguish between open and closed lanes. The correct configuration for the flaps is detailed on working drawing P7402.

Signs should not be manually changed when the sign vehicle is standing on a live traffic lane.

The colours of the system shown in Figure 10.1 are as follows:
 * upper sign display board: non-reflective grey;
 * lower sign display board: retroreflective yellow in the same material as for MLC sign diagram 7403 (see paragraph O10.7.4); and
 * lamps: amber.

The sign to diagram 610 on the lower panel should be reflectorised in accordance with the relevant special signs authorisation. The lower sign panel should be reflectorised using the same material as that specified for signs to diagram 7403; see paragraph O10.7.4.

Light arrow systems where the lower sign display board is non-reflective yellow and which have been used on trunk all-purpose roads and motorways before 1 April 2009 may continue to be used on such roads until 31st March 2011. Such light arrow systems may be used on other roads if the relevant traffic authority has obtained written authorisation from the Secretary of State for Transport in England or the equivalent national authority in Scotland, Wales or Northern Ireland.

The lamp layout shown is indicative; for details of the precise number and layout of lamps refer to the relevant special signs authorisation. The halogen light-emitting arrow lamps under the current signs authorisation are required to pulse at a rate of 30 to 50 flashes per minute, with the on-period twice the length of the off-period, and when the light-emitting arrow lamps are operating the two synchronised xenon flashing lanterns shall only flash during the off-period of the light-emitting arrow lamps. 116