these slower roads more place names on a sign will be acceptable. The principle should nevertheless be followed that a place once mentioned on any class of directional sign should continue to be shown on that class of sign until it is reached.
On purely local directional signs no difficulty arises in the selection of place names.
147. Since it is not possible for us to design every directional sign individually our designer, Mr. Jock Kinneir, has prepared rules which should govern the design of these signs, both map and stack type . These are in Appendix VIII . It will clearly be necessary to amplify and modify these rules in the light of experience during the period before new Regulations are issued. However, in due course a definitive set of rules will be issued which will then have to be followed by highway authorities and signmakers working on their behalf.
148. Stack type advance direction signs, on which arrows are ranged right or left of place names shown in panels one above the other, can usually achieve the same legibility as map type signs within a somewhat smaller area. We think, however, that this potential saving is more than outweighed by the great value of the visual indication of the nature of the junction ahead which is given by the route symbol on a well designed map type sign. We considered whether stack type advance direction signs might be used regularly at simple junctions, but we think that the image of a junction which is presented to drivers by a map type sign is so useful a safety measure that we recommend the use of stack type advance direction signs (figures 85 and 88) only where the roadside space available is not wide enough to admit a map type sign. At all other sites advance direction signs should be in map form (figures 74 to 84, 86 and 87) . Stack type signs should, however, continue to be used for advance direction signs to purely local destinations (figure 89).
149. Except on trunk roads it has hitherto been the practice to leave it to the discretion of local highway authorities to decide whether a road junction merits a full complement of directional signs. In the interests of uniformity more guidance on this should be given to local highway authorities by the Departments . We suggest that such guidance should take into account the speed and volume of traffic using a junction together with the importance of the junction in relation to the national and local road networks. These factors are, of course, variable and the standard of signing at each junction should therefore be kept under review and improved to include all three elements (advance direction sign, direction sign and route confirmatory sign) where changing conditions make all of them necessary.
150. We recommend that on Primary routes advance direction signs (other than local advance direction signs, to which we refer elsewhere) should have
white place names and yellow route numbers on a green background even
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