lights situated close together produce a confusing appearance. High intensity flashing warning lights should not be used on barriers to diagram 7105 within tapers where sequentially flashing warning lights are used; see paragraph O4.7.17.
O4.7.16 High intensity flashing warning lights may be used to supplement signs to diagrams 606, 609, 610, 616, 633, 829.1, 829.2, 829.3, 829.4, 7101.1, 7102 or 7105. When the warning lights are placed by the police in accordance with regulation 54(1)(b), the light emitted by them must be blue. It should be amber in all other cases.
O4.7.17 Consideration shall be given to the use of backlit sequentially flashing warning lights to highlight taper coning in both daylight and darkness. Research has shown that use of these lights can help drivers to identify and make the necessary change of lane much earlier than with conventional lights, thereby reducing the risk of taper strikes. The use of these lights shall be restricted to lead-in and intermediate stepped tapers involving a lane drop, and shall not be used when a lane or lanes are narrowed, at a changeover, or a crossover. Where these lights are in use, high intensity flashing warning lights shall not be used on barriers to diagram 7105 within the taper.
O4.7.18 The backlit sequentially flashing warning lights have been authorised for use on the motorway and trunk road network. For use on other roads, the need for specific authorisation of these lights should be checked with the relevant Overseeing Organisation prior to their use.
O4.7.19 On motorways and dual carriageway trunk roads with a permanent speed limit of 50 mph or more, backlit sequentially flashing warning lights shall be used to highlight both lead-in and intermediate stepped tapers within the works.
O4.8TEMPORARY LIGHTING
O4.8.1 Road works sites may be floodlit and in some cases temporary lighting may be installed to enable work to proceed after dark. Special attention should be given to the orientation of the lighting units to ensure that drivers are not dazzled. The quality of the illumination should be such that the work involved can be carried out to the appropriate standard. Safety fencing may be necessary if temporary lighting columns are erected.
O4.8.2 The temporary lighting of crossovers is dealt with in British Standard BS 5489-1:2003 and additional advice is given in Section 5 of TA 92 "Crossover and changeover design" (DMRB 8.4.6).
O4.9SIGNS AUTHORISATION
O4.9.1 Certain traffic signs illustrated in the Regulations are specifically prescribed only for use at road works. Any other sign prescribed in the Regulations or authorised by the Secretary of State may also be used, provided that the appropriate criteria are met and that any necessary orders have been made.
O4.9.2 Only prescribed traffic signs, or traffic signs that have been authorised by the Secretary of State may be used. Practically every foreseeable road works situation can be dealt with by the use of official signs for which designs are readily available. If new signs are required the Overseeing Organisation must be consulted and authorisation obtained. In exceptional cases special signs which comply with regulation 53 can be used.
O4.10DELINEATORS
O4.10.1 Cones and cylinders are used to delineate the traffic lane a driver should take past an obstruction, accident or road works. The portability of these devices is of particular advantage in emergencies or when they are used to delineate works which move progressively along a carriageway. Cones to diagram 7101.1, flat
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