Citation

Rex CH. Highw. Res. Board bull. 1959; 226: 27-55.

Copyright

(Copyright © 1959, National Research Council (U.S.A.), Highway Research Board)

DOI

unavailable

PMID

unavailable

Abstract

Computed seeing effectiveness ratings are presented in terms of two of the principal factors: Relative visibility and the relative visual comfort. Traffic ratings used by various highway departments on elimination studies are described. It is concluded that computation of simplified seeing factor ratings has many advantages including: (1) prediction of the effectiveness of roadway lighting in understandable terms of roadway user benefit, (2) application and luminaire performance variables may be explored, evaluated, and controlled in design for optimum over-all efficiency, (3) comprehension of objectives will be improved, complexity reduced, and standardization possibilities revealed, (4) progress in dynamic visual research under night driving conditions will be encouraged by a method for the use of the laboratory and field data available, and (5) time will be conserved. Seeing benefit ratings and traffic ratings will indicate how much better good roadway lighting is when compared with poor lighting. Traffic benefit ratings also help in determining the importance of a good relative visual comfort rating compared with a high relative visibility rating.