抄録
This study involved the subjective visibility evaluation of LED roadway delineators under different visibility conditions both at daytime and nighttime. The experiment was conducted using a road in Hokkaido, Japan under natural foggy conditions. The authors employed three types of LED delineators to examine how their visibility differed across various levels of luminous intensity. Twenty women participated as subjects. They were asked to evaluate the visibility, glare, and safety of each test accessory. In heavy fog, LED delineators earned a high rating of subjective visibility at daytime and nighttime. It was also recognized that the luminous intensity of the light-emitting elements in the delineators required adjustment depending on the degree of visibility reduction due to fog: To make the delineator "visible" from the observation distance of 200-m under foggy conditions with a visibility distance of 100-m, luminous intensities of 1,000-cd and 70-cd are desirable for daytime and nighttime, respectively.
