Citation

Rex CH, Franklin JS. Highw. Res. Board bull. 1960; 255: 101-116.

Copyright

(Copyright © 1960, National Research Council (U.S.A.), Highway Research Board)

DOI

unavailable

PMID

unavailable

Abstract

Argument is made that visual benefit ratings should accompany ratings of traffic benefits. The use is presented of the guth evaluator for rating the relative visual comfort of roadway lighting systems. Relative visual comfort ratings are compared for similar roadway lighting systems using two different evaluation methods. The study involved a central business district group involving fifty people. The computed ratings are based on use of a method of rating the relative visual comfort of lighting systems. The visual comfort ratings are relative to the motorist-observer sensation which would be at the borderline between comfort and discomfort (bcd), for the system of luminaires and the lighted roadway, or the lighted roadway only. A computed rating is the arithmetic average of the ratings over a cycle of fourteen observer positions for a longitudinal distance twice the luminaire spacing. The computed ratings are shown from two field brightness foot lambert condition. The testing equipment and evaluating means are described. The evaluator may be used to demonstrate and provide better understanding of the fundamentals involved in improving relative visual comfort. An increase in field brightness improves the relative visual comfort ratio unless accompanied by a corresponding increase in the combined brightness of the system luminaires. The latter may be increased within the limits of the relative comfort ratio without decreasing the relative visual comfort. The evaluator demonstrates that progress involves higher brightness at or near the pavement level with lower brightness up at the luminaire mountings. Numeric l ratings for the visual comfort quality of roadway lighting is an essential step toward increasing the night use of the public investment in automotive transportation facilities. An indoor population study-type exploration was made of judgments of bcd sensation. A table presents the variation of individual bcd sensations at any field brightness.