Citation

Woltman HL, Youngblood WP. Transp. Res. Rec. 1976; 562: 79-92.

Copyright

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

DOI

unavailable

PMID

unavailable

Abstract

The purpose of the study described in this paper is to measure the comparative brightness of contemparary traffic signing materials under both the conventional 2-beam and the proposed 3-beam head- lamp systems. Because most traffic signs are retroreflective, sign brightness is highly dependent on the illuminance supplied by head lamps. A systematic evaluation performed by the authors led to a general understanding of sign luminances for conventional 2-beam performance for Interstate Highway System signs. The design experiment was developed to evaluate the relative change in sign luminance should the 3-beam system be standardized. Photometrically selected 2- and 3-beam head-lamp sets were obtained from 2 lamp manufacturers, installed in standard-size passenger cars, and aligned. Night luminance measurements were made of retroreflective sign materials by using a telephotometer installed at driver eye position. Luminance measurements were taken at 7 distances from the traveled lane on a uniformly graded tangent section of test road. The proposed low beam is not different from the current low beam. The sign luminance under the proposed mid beam is approximately 4 times greater than it is under the low beam. The high beam provides substantially more light, and sign luminance under the proposed high beam is approximately 2 times greater than it is under the current high beam.