Citation

Helmers G, Rumar K. Transp. Res. Rec. 1974; 502: 58-69.

Copyright

(Copyright © 1974, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

Night driving visibility distances were measured in a series of experiments. Road surface was the main independent variable. Two rough and 2 smooth road surfaces with large variations in their retroreflective qualities were used. Reflective qualities were further varied by measuring visibility distances on both dry and wet road surfaces. The size of the obstacles was 0.4 by 0.4 m (1.3 by 1.3 ft). The luminance factor was varied between 2 percent and 26 percent. Visibility distances were obtained in the following full-scale simulated driving situations: (a) low beams without opposing light, (b) low beams opposing low beams, and (c) high beams without opposing light. Safe visibility distances were normally obtained in high-beam situations. Low beams opposing low beams constituted the main safety problem. So, in meeting situations, a low degree of specular reflection (low glare) from the road surface is more important than high retroreflection (high brightness).