Page:UK Traffic Signs Manual - Chapter 3 Regulatory Signs. 2008 (Second Impression 2008).pdf/79

 be erected on each side of the road or, in the case of a dual carriageway, on the near side and on the central reservation (direction 8). The end of the clearway is indicated by a sign to diagram 642 supplemented by an "End" plate to diagram 645. These signs should be erected on each side of the carriageway, mounted back to back with the commencement signs where appropriate. Smaller repeater signs, which may alternate from one side of the carriageway to the other, should be placed at intervals of approximately 1600 m in each direction where the speed limit is 60 mph or more. Where the speed limit is 40 or 50 mph, the spacing should be reduced to 1100 m and 1350 m respectively, to maintain an interval between successive signs of approximately 60 seconds. Where street lighting is provided, the repeater signs may be mounted on the lamp columns.

Where a road joins or crosses a clearway, a commencement sign to diagram 642 should be erected on each side of the carriageway of that road to face traffic approaching the junction. The supplementary arrows prescribed by the 1994 Regulations as diagrams 643 and 644 are no longer used. A distance plate is not used as in most cases traffic can turn either left or right into the clearway. However, distance plates should be provided if the road is a slip road leading to a dual carriageway. For traffic turning into the side road and leaving the clearway it will normally be sufficient to provide a single sign to diagram 642 together with an "End" plate on the left hand side of the minor road. Complex junctions with splitter islands, link roads or slip roads might require additional signs.

Appropriate sign and plate sizes are specified in Appendix A. No road markings are used in conjunction with a 24-hour clearway.

The urban clearway prohibits stopping during peak periods, but is effectively a prohibition of waiting and loading as drivers may stop to pick up and set down passengers. It applies to both sides of the carriageway and is indicated by the sign to diagram 646 erected on each side of the road to face oncoming traffic. The sign indicates two time periods representing the morning and evening peak periods; it cannot be varied to show a single time period such as 8 am to 6 pm. As road markings are not used with urban clearways, signs should be provided in both directions just after each side road junction. The signs should be sited a sufficient distance from the junction to enable them to be read by drivers turning into the clearway, but generally no more than 45 m measured from the backline of the side road. Care will need to be taken when siting signs at a staggered crossroads or where junctions are very close together. Where junctions are more than 400 m apart, additional signs should be provided to maintain a spacing of not more than 400 m. The end of the clearway is indicated by the sign to diagram 647. In most cases, this will be mounted on both sides of the road back to back with the commencement sign to diagram 646. Signs to diagrams 646 and 647 are not normally provided on side roads that join or cross an urban clearway.

The Regulations prescribe two sizes for the sign to diagram 646. The larger size would normally be used on roads with a speed limit of 40 mph or more. Only one size is prescribed for diagram 647. 77