Appendix VIII
Rules for the Design of Road Signs
(see paragraph 147)
Alphabets
(i) There are two alphabets for use on traffic signs and no others should be used. They are the Transport Medium and Transport Heavy alphabets (figures 1 to 6).
(ii) Each alphabet comprises capital and lower-case letters, numerals and associated characters, and each of these is placed on a tile to assist in spacing.
(iii) The Transport Medium alphabet is for use only for light (white or yellow) letters on a dark (blue, green or red) ground, and the Transport Heavy alphabet is for dark letters on a light ground.
(iv) Letter size shall be expressed as inches of 'x' height, which is the height of a lower-case letter 'x' within the alphabet concerned. The height of capitals should normally be expressed in terms of the ' x' height of the alphabet from which they are taken, for example, 'capitals from the 4 inch "x" height alphabet'. Where, however, capitals alone are used on a sign they may be described in terms of their actual height.
(v) Stroke-width, referred to as S/W, is the thickness of the capital letter I in the Transport Medium alphabet whatever size of alphabet is being used on the sign. This stroke-width is never based on the Transport Heavy alphabet.
Layout of Signs
A. General
(i) All dimensions are expressed in terms of stroke-widths.
(ii) Spaces are measured between the tile edges of letters (and never between the letters themselves), but direct to symbols, borders and arrows.
(iii) All place names on a sign shall be in letters of the same size, regardless of the relative importance of the place. A smaller letter size may only be used for a name which is too long to fit into a reasonable sized sign and which cannot be hyphenated or abbreviated.
(iv) Route letters and numbers shall be from the same size alphabet as is used for the related place name.
B. Letter and word spacing
(i) Words are formed by butting tiles closely together.
(ii) Tiles of words stacked one above the other shall be butted closely together (but see also C(iv)(g)).
(iii) Related words on the same line, as in a phrase, shall be separated by 1½ S/W.
(iv) Route letters and route numbers shall be separated by 1½ S/W.
(v) Route letters shall be 2 S/W away from place names when on the same line.
(vi) There shall be 3 S/W between a route number and a bracketed route number on the same line.
(vii) When a two-word place name has to occupy two lines the words shall be centred on one another.
143
