Page:UK Traffic Signs Manual - Chapter 8 - Part 1 (Traffic Safety Measures and Signs for Road). Designs 2009.pdf/139

SINGLE CARRIAGEWAY ROADS

Guide islands should be provided where a single three-lane carriageway road is reduced to one or two lanes; see Plans SC6 and SC8. Minimum taper lengths for guide islands are given in Table A1.3 (Appendix 1). Lengths of guide islands excluding tapers are given in Table 5.6 below.

When guide islands are used in conjunction with positive trafﬁc control (priority signs, "STOP/GO" signs, and traffic signal control) the taper lengths should be as given in Table 5.3.

For short lengths of shuttle working, i.e. 50 m or less, chicanes can be used to reduce traffic speeds, where necessary, to less than 10 mph. At least one chicane in each direction is required, of the minimum size to allow a large vehicle to pass through slowly, and traffic must first be brought to a halt by positive traffic control and then released in small batches by careful use of “STOP/GO” signs or manually controlled portable traffic signals. The principle is shown in Plan CH1. Where it is impracticable to provide a chicane in one direction, for example, because of the presence of a junction, an alternative trafﬁc management arrangement should be used in that direction to ensure that traffic speeds are reduced to less than 10 mph. 138