In these cases the designer should contact the Highway Authority, which will consider alternative solutions.
D5.10.3 Normally the approval of the traffic authority will be required before portable traffic signals are placed on the highway (see direction 53). Where portable traffic signals are placed on the highway by undertakers under powers in the New Roads and Street Works Act 1991 then prior approval is not required. However, the undertaker must give advance notice of the use of portable traffic signals (NRSWA 1991 sections 54 and 55). The traffic authority may give directions as to the use of portable traffic signals. Approval by the traffic authority is always required if the section operated by portable traffic signals includes a junction (direction 53).
D5.10.4 The signal equipment used must be Type Approved and traffic signals should normally be vehicle actuated unless works are being undertaken under 'use of chicanes' (see Section D5.12), ’extended all-red periods’ (see Section D5.13) or unless otherwise instructed by the Highway Authority.
D5.10.5 Advice regarding signal control and setting-up procedures can be found in Part 2: Operations, Section O3.21. Useful advice is also given in the Department for Transport booklet "An introduction to the use of vehicle actuated portable traffic signals".
D5.10.6 The position of the signals and signs relative to the start or finish of the shuttle lane affects the efficient flow of traffic. The recommended positions are shown in Plans SC7 and SC8. For most road works sites where signals are used, two-phase control for shuttle working is all that is required.
D5.10.7 The use of two traffic signals should be considered on each approach, especially where traffic approaches at high speed. In some circumstances this may not be necessary or physically possible. In such cases, Plan SC7 shows alternative positions for the signals:
- on the near side of the approaching traffic at each end of the works; or
- on or near the centre line of the road at both ends of the works.
D5.10.8 The Highway Authority may require variants of these layouts to meet particular conditions. The main factors which need to be considered are the duration of the works, visibility of the signals, the magnitude of the traffic flow and whether the cable crossing can be safely accommodated, see paragraph D5.10.9 below.
D5.10.9 Where the signals are positioned on the near side of the approaching traffic, the effectiveness of the detectors used with vehicle-actuated operation is maximised. Where the signals are connected by cable, the layout requires the cable to cross the running lane. To prevent damage and minimise the danger to road users, in particular cyclists, motorcyclists, and horse riders, this cable should be fitted in a cable protector secured against movement. The crossing protector should not present a hazard to road users passing over it, especially cyclists and motorcyclists. The Highway Authority should be satisfied that the cable crossing protector is safe and fit for use.
D5.10.10 A "RAMP" sign to diagram 7013 is required on each approach to the cable crossing.
D5.10.11 The "Traffic signals ahead" sign to diagram 543 is used to warn drivers that they are approaching traffic signals. It may be accompanied by a distance plate to diagram 572.
D5.10.12 The "JOINING TRAFFIC NOT SIGNAL CONTROLLED" sign to diagram 7022 together with an "Other danger ahead" sign to diagram 562 is required within a length of road controlled by portable traffic signals at each uncontrolled junction with a side road. On trunk roads the sign shall always be used if appropriate. See also paragraph D5.15.7.
D5.10.13 When traffic signals are not operating (removed from use) for any significant period of time, they should be bagged. For periods of less than one week, signs to diagram 7019 may be erected instead to indicate that the signals are not in use. The signs should be fixed to the traffic signal posts, and may also be erected
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