Effects of Luminous Intensity and Modulation on Nighttime Perception of Automated Driving System Marker Lamps

An automated driving system (ADS) marker lamp is turned on to signal to surrounding road users that a vehicle is operating in automated driving mode. SAE J3134 specifies that ADS marker lamps should emit a blue-green color. However, current Japanese regulations do not prohibit the use of this color for lamps installed on conventional vehicles. As one potential approach to distinguishing marker lamps from non-ADS lamps, modulating their luminous intensity is considered. Consequently, this study examines how changes in luminous intensity or modulation pattern affect their perceptual appearance. To investigate this, a horizontal lamp unit emitting blue-green light was positioned above the headlamp units in a darkroom. This setup simulated a nighttime scenario in which an observer views an automated driving vehicle equipped with a marker lamp mounted on the front edge of the roof from a distance of approximately 20 m. Twenty participants evaluated the effects of luminous intensity, modulation pattern, and modulation frequency on the visibility, glare, perceived annoyance, and perception of the direction-indicator lamp. The results indicate that both high luminous intensity and rapid modulation frequencies reduce visibility, increase glare and perceived annoyance, and interfere with the perception of the direction-indicator lamp. Therefore, such settings may be inappropriate for effective marker lamp design.