Page:UK Traffic Signs Manual - Chapter 7 -The Design of Traffic Signs 2013.pdf/53

MAP TYPE ADVANCE DIRECTION SIGNS

Figure 5-18 shows the basic design of the route symbol which should be used where a priority lane is segregated from the roundabout either by ghost markings or by a solid island. The symbol design remains the same for both diverge/merge and lane drop/lane gain situations. The width of the priority lane is always 2.5sw, regardless of the status of the route. The remainder of the roundabout symbol is designed in accordance with the details given in paras 5.39 and 5.40.

The basic design is applicable to left turn route arms that are angled between 30° above the horizontal and 30° below the horizontal, as shown in figure 5-19. Where the arm is inclined at a greater angle, the design has to be adjusted. Figure 5-20 shows that with the arm pointing downwards at 45°, the radius of the priority lane has to be reduced to 7.5sw. The gap between the lane and the roundabout is increased from the normal 2sw. Figure 5-21 shows that with the arm pointing upwards at 60°, the priority lane can be accommodated by offsetting the roundabout symbol to the right. However, in this case it may be necessary to adjust the design of the symbol should it not reflect the actual road geometry. 52