11.15 Figure 11-10 shows a final advance direction sign on a motorway. Sign 4A is the conventional design with the junction number in the bottom left hand corner. By moving the junction number to the top left hand corner, as shown on sign 4B, and lowering the side destination block, the height of the sign (and hence overall area) can be substantially reduced. However, this was only possible because the horizontal length of the forward destination was very short. Signs 4C and 4D demonstrate that with a longer length of forward destination, the smaller sign is the one with the junction number at the bottom. Another consideration is the length of the bottom line of the side destination. Although this can be positioned close to the bottom border, as shown on sign 4B, this may not be possible when the distance to the junction is added. Also, as one mile and 1⁄2 mile advance direction signs do not normally show a forward destination, there would be no saving on the height of the sign by placing the junction number at the top.
11.16 The design rules in previous sections show how triangular warning signs and regulatory roundel signs are added to direction and advance direction signs. The more complex the information given within the triangle or roundel, the larger it needs to be, relative to the main sign, to ensure that it is still legible to drivers (see Appendix D for sizes). Where this results in very large signs with significant amounts of blank space, consideration should be given to placing the warning / regulatory information on separate signs, and not integrating it into the main direction and advance direction signs. Where an advance direction sign incorporates two triangles or roundels, care must be taken to minimise wasted space. Figure 11-11 shows a sign for a three-way junction where the ahead route has a level crossing with electrified overhead cables. The design of sign 5A assumes that the left hand triangle should be placed on the vertical route arm. However, this results in an overlarge sign. By placing the right hand triangle on the vertical arm, as shown in sign 5B, a more efficient design is achieved. Depending on the number of destinations shown, and the length of the place name blocks, it may be possible to reduce the area of the sign face further by using a stack type sign as shown in sign 5C.
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