kept very much in mind has been the implication of lettering upon the size and proportions of signs and consequently upon their cost.
We have studied the evidence which was before the Advisory Committee on Traffic Signs for Motorways and also the results of experiments carried out more recently by the Road Research Laboratory in which signs of equal area using serifed capitals, sans-serifed capitals and lower-case lettering were compared. Where the signs were of equal area it was found that there was little difference in legibility between the three types of lettering.
42. We recommend the use of lower-case lettering with initial capitals for traffic signs generally because we prefer it and because we think its outlines are more familiar to the reading eye. An additional factor is that in general a sign with lower-case letters is narrower but higher than one of equal area using capital letters; this is an advantage when site conditions restrict the width of sign for example on town pavements or on narrow country roads.
43. We believe that there is a small number of special signs for which capital letters should be used; these we specify later.
44. Our designer has at our request designed two alphabets of different weights with numerals and other characters. These are illustrated in figures 1 to 6. (Throughout this report figure numbers refer to illustrations in Appendix II.) The Transport Heavy alphabet is for use wherever signs have a light background and the Transport Medium wherever they have a dark background. We recommend that these be used for all the signs included in this report.
45. It is important that traffic signs should not only be easily recognisable as such but also that one class of sign should be immediately distinguishable from another. Thus drivers may, for example, receive a general warning of danger before they reach the point at which the message on the sign becomes readable. Both colour and shape can, and we think should, play a part in achieving this object.
46. The Protocol requires that signs should be of three basic shapes—triangular for warning signs, circular for those giving definite instructions and rectangular for informatory signs . It further requires that:—
(a) warning and prohibitory signs (with one or two exceptions) should have a red border with a white or light yellow ground and black or dark symbols;
(b) mandatory signs should have white symbols on a blue background;
(c) directional signs should be in light lettering on a dark background, or vice versa; and
(d) other informatory signs should have white legends on a blue background or, in certain cases, black symbols on a white rectangular background within a blue surround.
The signs which we have recommended and which are illustrated in Appendix II follow these principles. The colours which we have chosen for directional signs, and our reasons for doing so are set out in paragraphs 136 and 139.
47. With the exception of traffic signals and zebra crossing beacons, all posts, brackets and fittings used for the mounting of signs, as well as the backs of signs and any bracing, should be coloured grey.
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