Citation

Dickinson HC, Halvorson C. Highw. Res. Board Proc. 1932; 1932.

Copyright

(Copyright © 1932, National Research Council (U.S.A.), Highway Research Board)

DOI

unavailable

PMID

unavailable

Abstract

A report is presented on an extensive series of tests of motor vehicle headlighting including: visibility distances on straight roads, visibility distances in general both with and without opposing cars, spread needed for headlight beams and glare and intensity of illumination needed to enable the driver to see the road shoulder. A striking conclusion from the tests of beam spread is that the great emphasis upon sharp cut-off and exact aiming in vogue a few years ago had no rational basis in headlight performance. A most important element in avoiding danger in meeting other cars was found to be adequate light on the roadside since sight to the rear of the opposing car is almost negligible. Conclusions defining headlighting conditions conducive to best results and suggestions for future study are presented.