Citation

Forbes TW. Highw. Res. Board bull. 1960; 255: 61-71.

Copyright

(Copyright © 1960, National Research Council (U.S.A.), Highway Research Board)

DOI

unavailable

PMID

unavailable

Abstract

Combining the results of certain published researches yielding background information on human reactions brings out certain relationships of importance in traffic design, operation and safety. Some of these affect night driving efficiency. Increased task difficulty leads to longer perception-judgment-response times. At night, driver response time may be slowed an additional amount by reduced visibility. Data on time for dilation and constriction of the pupil of the eye in adapting to light and to dark indicates that the dark hole effect in entering a tunnel can be eliminated by design taking account of the human reaction. It also explains accident experience reported in crossing certain highly illuminated thoroughfares and suggests remedial measures. Reduced sensitivity and a change of relative sensitivity to colors may lead to driver errors. These characteristics of the human eye should be given proper consideration in highway design and traffic engineering activities to improve operation and reduce hazards. Fatigue results in reduced human efficiency and, for most drivers, probably will be greater at night. Studies in industry indicate that moving bright sources in the periphery of vision tend to induce fatigue. They may be also a factor in inducing sleep. An experimental study of drowsiness in driving showed an increasing frequency of eye closure leading up to actual drowsing behind the wheel. Turnpike and other studies of one car accidents seem to indicate a high proportion of sleep accidents between midnight and 6:00 a. M. It is suggested that discomfort glare may be of great importance as a fatigue and drowsiness inducing factor and that the threshold for discomfort glare may be lower under sleep deprived and fatigued conditions of the driver. Drivers must realize that critical phases of the driver's task often are even more critical under night driving conditions. Proper consideration of eye characteristics in design of lighting, signing and marking of highways can help to reduce hazards from the various factors discussed.