rely mainly upon symbols but employ different shape and colour codes. The warning signs, for example, bear black symbols on a yellow, diamond-shaped background and the prohibitory and mandatory signs are circular in shape with black symbols within a red circle and black legends on a white background.
32. The other two main systems of traffic signs are the American and African systems. In the former most signs consist of words rather than symbols and warning signs are diamond shape with black lettering on a yellow background while regulatory signs are rectangular with black lettering on a white ground.
The African (or Johannesburg) system, devised in 1937, follows the United Kingdom in placing a symbol on a separate rectangular plate below a red triangle for danger signs, a red disc for prohibitory signs and a red circle for mandatory signs. But the background of the rectangular plate is yellow.
33. We rejected the 1953 Convention system which, apart from having only two adherents in Europe, did not seem to us to be superior as a whole to the 1949 Protocol system. We also rejected the African system which so closely follows United Kingdom practice as to be open to similar criticisms.
34. The Road Research Laboratory had compared for us a selection of the present United Kingdom designs with the 1949 Protocol and American equivalents. The question for which an answer was sought was-"If signs of each of the three systems had the same area, which system would have the most effective designs to drivers educated in their meaning?". As the area of a sign roughly determines its cost the most effective system is also the cheapest. In the tests therefore signs of equal area were compared and the observers taking part had been fully educated.
These tests proved that the class of sign was recognised at the greatest distance in the American system, the Protocol system was second at a distance of 9 per cent. less; the United Kingdom system was least readily recognisable at 19 per cent. less distance. In most cases the American and Protocol systems use simple geometrical shapes where the United Kingdom system uses composite designs which seem to us to lack integration.
The average distance at which the message on signs could be identified was greatest for the Protocol system, 15 per cent. less for the United Kingdom system and 19 per cent. less for the American. The superiority of the Protocol system in this respect is due mainly to its extensive use of symbols.
35. The complete identification of the sign seems to us to be the more important of the two criteria and we have therefore concluded that the Protocol system is, where the public has learnt the meaning of the symbols, the best of the three.
36. Our investigation led us to the conclusion that the choice before us was threefold:—
(a) to try to design an entirely new set of traffic signs, which would have to be at least as effective as any system at present in use;
8
