BRIGHTNESS OF SELF-LUMINOUS DELINEATORS IN DIFFERENT COLORS

The optimum brightness for a self-luminous delineator has been investi gated by seven observers with normal color vision. In the dark room, a small size stimulus (3.4 ft and 5.2 ft diameter) was centered against a white uniform background which has a 10 degree diameter. These stim ulus sizes each correspond to 150 and 225 mm diameter which are viewed from 150 m. Three luminance levels (12, 130, and 1050 cd/m(2)) of the uniform background and four colors of the stimulus were investigated. CIE 1976 chromaticity coordinates of the stimuli were red (0.362, 0.5 12), green (0.173, 0.540), blue (0.169, 0.205) and white (0.208, 0.493 ). The observers adjusted the luminance of each stimuli to the minimum brightness which were suitable for traffic delineators. There was no statistical difference between these luminances obtained against two s ize stimuli. These luminances were calculated to visibility level, and the relationship between these visibility levels and stimulus colors were discussed. These results showed that these visibility levels can be presented by background luminance and color difference between the stimulus and the background. Furthermore, by additional experiments we found that these adjusted luminances don't give discomfort glare. In these experiments the same observers adjusted maximum luminance withou t discomfort glare against. 2.3 degrees stimuli on uniform backgrounds 912 and 130 cd/m(2)).