Title

TRAFFIC SIGNAL LUMINANCE AND VISUAL DISCOMFORT AT NIGHT

Document Type

Journal Article

Publication Date

2001

Subject Area

operations - traffic, infrastructure - traffic signals, mode - bike

Keywords

Yellow interval (Traffic signal cycle), Traffic signals, Traffic lights, Traffic control signals, Specifications, Red interval (Traffic signal cycle), Night vision, Luminous intensity, Luminance, Light emitting diodes, LEDs, Human comfort, Highway traffic signals, Green interval (Traffic signal cycle), Comfort, Amber phase

Abstract

The visual discomfort from simulated traffic signals under nighttime viewing conditions was assessed. Discomfort increased with increasing signal luminance and decreasing viewing distance. Color identification of signals was very high for all signal colors and luminances studied. Red signals meeting luminous intensity specifications of the Institute of Transportation Engineers (ITE) and specifications being drafted in Europe were unlikely to cause visual discomfort under the conditions tested. Green and yellow signals meeting ITE and European specifications were more likely to cause visual discomfort. Dimming signals using light-emitting diodes might be a feasible strategy for minimizing discomfort under some nighttime viewing conditions.