Citation

Grime G. Highw. Res. Board bull. 1953; 68: 54-61.

Copyright

(Copyright © 1953, National Research Council (U.S.A.), Highway Research Board)

DOI

unavailable

PMID

unavailable

Abstract

Measurements of glare intensity from the lower (dipped) beams of vehicle headlights were made at sites in Texas, Maryland, New Jersey, and in the District of Columbia in the summer of 1952. The results show that in the two states which had well-established vehicle-inspection procedures (New Jersey and the District of Columbia), glare was slightly less than in Maryland, which had no inspection, and in Texas where inspection had just begun. At all places, a few very-badly adjusted headlamps were met. Although glare from lower beams was found to be reasonably low, the situation as regards deterioration was less satisfactory. With the help of the bureau of public roads, measurements were made at two inspection stations in washington of the maximum intensities of the country beams of vehicles as presented for inspection. It was found that the light output of many lamps had deteriorated badly, but because the candlepower limit at inspections was so low, few of these deteriorated lamps were rejected. Combining these results with those of the glare survey in washington, rough calculations were made which indicated that, because of the large deterioration allowed, the distance a washington driver can see when meeting another motorist at night is, for many such meetings, only a fraction of what it might be if all lamps were maintained as new. Counts made on rural roads in Texas showed that 20 to 25 percent of drivers met refused to dip (change to lower beam). It is not known whether the same high proportion is met elsewhere, but it appears probable that most of the glare nuisance in the United States is due to this reluctance to use the lower beam.