O3.21.21 Where personnel are working on signals in close proximity to traffic, other than in short-term situations, the traffic signal maintenance sign (prescribed variant of diagram 7010.1) should be provided in advance of the signals. This sign must be reflectorised if it is not directly illuminated.
O3.21.22 The "TRAFFIC CONTROL AHEAD" sign variant of diagram 7010.1 should not be used to warn of traffic control by traffic signals. It should be used only at road works to warn that there is manual control of traffic ahead by the use of "STOP/GO" signs to diagrams 7023 and 7024. See Section O3.22.
O3.21.23 Traffic control arrangements should be reviewed to ensure delays are kept to a minimum and amended to suit the circumstances, adjusting the associated signs accordingly.
O3.21.24 If traffic signals that operate during the day are removed at night or over a weekend, the "traffic signals ahead" signs to diagram 543 must also be removed.
O3.21.25 The "WHEN RED LIGHT SHOWS WAIT HERE" sign to diagram 7011 is normally placed about 2 m in advance of portable traffic signals when use of a "stop" line to diagram 1001 is inappropriate or impracticable. The sign indicates the position at which the first vehicle should wait when the signals show red. As a variant of the sign to diagram 7011, the words "RED LIGHT" may be replaced by "STOP SIGN". See also Part 1: Design, Section D5.8. Careful positioning of the signals and of the sign is essential to ensure that vehicles from the opposite direction have sufficient room in which to clear the waiting vehicles and to return to their own side of the road, if necessary.
O3.21.26 If portable traffic signals are not operating, they should be removed or at least turned away so that it is clear that they are not in operation.
O3.21.27 At sites with high traffic flows and/or poor carriageway alignment, it may also be appropriate to keep sufficient "TRAFFIC CONTROL AHEAD", "WHEN STOP SIGN SHOWS WAIT HERE" signs in reserve to enable "STOP/GO" traffic control, complying with Section D5.8 of Part 1: Design, to be implemented quickly in the event of failure of the traffic signals.
O3.21.28 Where a junction is normally controlled by "GIVE WAY" signs and the designer has decided that the level of traffic or visibility problems require the minor road or access to be controlled by signals, both the junction and the shuttle lane should be controlled by a multiphase portable signal controller and the "GIVE WAY" signs and lines should be temporarily masked or removed. Any cable crossing protectors used should be sited away from turning traffic and where braking and acceleration are unlikely to occur.
O3.21.29 Where the junction is normally controlled by permanent signals, the position of the proposed works will dictate the most appropriate course of action. A temporary change in the position of the stop line and/or one signal head may suffice. Should the vehicle detectors for the permanent signals be located within the area of the works or if traffic is diverted so that the vehicle detectors cannot register the passage of vehicles, the traffic signal controller should be switched to provide a permanent demand on that phase. If the works are to continue for more than a few days and delays are likely as a result of fixed time operation, alternative detection arrangements should be considered.
O3.21.30 Other situations may require the permanent signals to be switched off to allow traffic to be controlled by temporary signals (a reconfigured permanent signal controller and signals to diagram 3000), or by a multiphase portable signal set, or by one of the manual methods of traffic control. If any of the permanent signal heads cease to be relevant, they must be covered. A typical example would be a two-way road temporarily made one-way.
O3.21.31 Where the road works do not actually include a junction, but one is so close that difficulties may be encountered, multiphase control of the junction and shuttle lane may be inevitable, even though either the junction or shuttle lane taken in isolation would not require signal control. Local Transport Note 1/98,
“The installation of traffic signals and associated equipment” states they should be to the same standard as permanent signals.
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