Road meteorological observatories measure visibility with visibility meters. However, visibility values measured by visibility meters stem from the meteorological definition, which comes from a perspective different from that of road use. Subject experiments were therefore conducted with road videos in blowing snow conditions to clarify the difference between visibility perceived by drivers and that measured with a visibility meter. The experiments revealed that visibility perceived by drivers in blowing snow was approximately 70 m lower than conventionally measured visibility. Also, a high correlation was observed between the visibility perceived by drivers and the sum total of projected area of snow particles passed through a unit area in a unit time. It was also learned that the visibility perceived by drivers during blowing snow was affected by the intensity of visibility fluctuation, the presence or absence of snowfall, road surface conditions, the surrounding environment (i.e., urban or suburban), and the time of day, and is hardly influenced at all by the direction of the snowstorm. On the basis of the above results, the need for a visibility index for road traffic in blowing snow was suggested.


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    Title :

    How Drivers Perceive Visibility in Blowing Snow


    Subtitle :

    Human Subject Experiments on Visibility–-Viewing Videos of Blowing Snow


    Additional title:

    Transportation Research Record: Journal of the Transportation Research Board


    Contributors:


    Publication date :

    2009-01-01




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English




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