EXPERIMENTS WERE CARRIED OUT TO MEASURE TWO ASPECTS OF TRAFFIC SIGN LEGIBILITY- DISTANCE LEGIBILITY AND GLANCE LEGIBILITY. TURN RESTRICTION SIGNS OF THE FOLLOWING FORMATS WERE COMPARED: (A) PROHIBITORY (P), BASED ON AS 1742, WITH THE DIAGONAL EITHER OVER (O) OR UNDER (U) THE ARROW AND SLANTED DOWN TO THE LEFT (L) OR TO THE RIGHT (R) OR WITHOUT THE DIAGONAL (N); (B) MANDATORY (M) WITH A WHITE ARROW ON A BLUE GROUND (B) AS COMMONLY USED IN EUROPE AND A RED ANNULUS FORM (R). THE DISTANCE LEGIBILITY RESULTS SHOWED THAT THE MANDATORY BLUE (MB) FORMAT WAS GENERALLY RECOGNISED AT A SMALLER VISUAL ANGLE (GREATER DISTANCE) THAN THE MR FORMAT AND WAS ALSO SUPERIOR TO THE PROHIBITORY FORMATS. THE RANK ORDER OF THE PROHIBITORY FORMAT SIGNS, INCREASING FROM THE SMALLEST THRESHOLD VISUAL ANGLE (DECREASING FROM THE GREATEST LEGIBILITY DISTANCE) WAS: PN, PUL, POL, PUR, POR. THE GLANCE LEGIBILITY TESTS GAVE A SIMILAR RANK ORDER OF FORMATS TO THAT OBTAINED IN THE DISTANCE LEGIBILITY TESTS (A). THE NUMBER OF THE COVERING ABSTRACT OF THE CONFERENCE IS IRRD NO 255423.
Samenvatting