Citation

Woods DL, Rowan NJ. Transp. Res. Rec. 1976; 611: 38-44.

Copyright

(Copyright © 1976, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

The basic objective of this research was the evaluation of high-intensity reflective sheeting for use on overhead sign installations without external illumination. The effects of height above the roadway and angle of sign tilt with respect to the vertical, headlight configuration, and vehicle approach speed to sign legibility distance were measured for both an externally illuminated sign and a high-intensity reflective sheeting sign. It was concluded that the nighttime legibility distance of overhead signs was not appreciably affected by increases in mounting height in the range of 5.5 to 7.0 m (18 to 23 ft), by changes in angle of the sign with respect to the vertical in the range of.5 to +5 deg, or by vehicle approach speed. Headlight configuration, as expected, was the dominant factor in the legibility distance of the unilluminated high-intensity sign, further, the high-intensity sheeting can be used without external illumination for overhead sign installations in spite of the observed difference in legibility distances. The average legibility distances in 19 percent less with low beams and 5 percent more with high beams on the high-intensity sheeting without external illumination than on the standard installation without illumination.