During the summer of 1962, a study of windshield and instrument panel light reflectance characteristics was conducted on automobiles of several manufacturers for 1959 through 1962. Fifty-six automobiles were photographed and measured for daytime windshield light transmission, amount of dirt on windshield, instrument panel luminance levels and vertical size of speedometer and odometer numerals. Photographs are used to show variations in panel design and to give evidence of excessive windshield reflectance. Specific, practical and economic recommendations for changes in the visual engineering defects of current models are made in the text. Conclusions reached were that: (1) all of the fifty-six 1956-1962 automobiles tested had serious faults so far as the visibility of the highway and the instrument panel in the daytime is concerned. (2) the amount of light reflected from the top of the dash onto the windshield and into the eyes of the driver averages over 15% of the average scene luminance, (3) the amount of light scattering dirt on automobile windshields is small, a variable as one would expect, average only 4.8%, (4) glare sources of exceedingly high intensities were noted and all cars tested had chromium of various types in the field of the view of the driver, and (5) dash panel instrument illumination was generally much too low in the daytime to permit the meters to be seen at a glance. This is in addition to the problem in 4 above which further interferes with quick seeing.
Abstract