(2) General Principles.—Traffic signs, if they are adequately to fulfil their purpose, should comply with the following four general principles:
(i) They must be so designed and sited as to attract both by day and by night the attention of the persons for whom they are intended.
(ii) Their significance must be clear at a glance.
(ili) They must be so sited that sufficient time is allowed for road users to adapt their course of action to the indication given.
(iv) They must, so far as possible, be erected on a uniform system, and the use of unnecessary signs should be avoided. (Paragraph 8.)
(3) Uniformity and Standardisation.—Standardisation of signs and uniformity of practice in their use are of essential importance. (Paragraph 12.)
(4) International Agreements —Where applicable to conditions in this country, the general principles agreed by International Conferences on traffic signs should be observed. (Paragraph 13.)
(5) Removal of Unauthorised Signs —Unauthorised, misleading, or redundant signs should be removed and the existing powers of the Minister and of highway authorities in this connection should be reviewed and strengthened. (Paragraph 14.)
(6) Relative Urgency of Changes Recommended.—Recommendations involving replacement of existing signs by new or amended signs are divided into three broad classes:
(i) Where the change-over should be made as soon as possible in all cases.
(ii) Where the change-over should be made within a specified period of, say, from three to five years.
(iii) Where the new or amended signs need only be introduced as and when replacements of existing signs become necessary. (Paragraph 15.)
(7) Size of Signs—Generally the size of traffic signs should remain as at present. (Paragraph 17.)
(8) Colour of Signs.—Except in certain special cases the lettering on traffic signs should be black on a white ground. (Paragraph 18.)
(9) Lettering on Signs—The standard form of lettering recommended by the 1933 Committee should continue to be used. (Paragraph 21.)
(10) Siting of Signs.—On open roads, warning and informative signs should normally be placed at not less than 150 yards in advance of the places to which they apply. In appropriate cases an artificial background should be provided to improve conspicuity. (Paragraph 22.)
(11) Height of Signs—In open country the lower edge of signs should be 3 ft. 6 in. above road level. In towns there should be a clearance of not less than 6 ft. 9 in. over footpaths. (Paragraph 23.)
(12) Illumination of Signs.—By night the conspicuity and legibility of all traffic signs should approach as nearly as possible to daylight standards. Direct external illumination 1s to be preferred. Street tests should be undertaken to confirm that a suggested intensity of sign brightness is satisfactory under all lighting conditions.
On roads where vehicle headlamps are normally used the fitting of reflecting lenses is a satisfactory method of rendering signs conspicuous and legible by night, and they should be employed on all prohibitory, mandatory and warning signs on unlighted roads where direct illumination is not practicable. In these cases the red disc, ring or triangle
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