Browse Publications Technical Papers 2019-01-1005

Nighttime Visibility in Moonlight Conditions 2019-01-1005

This paper presents research on the effect that moonlight has on the visibility of objects in the roadway from a driver’s perspective. Two nighttime moonlight conditions are tested. The first condition involves no moon, and hence no moon light contribution. The second testing condition is during a full moon, and specifically when the moon is closest to the Earth, known as a super moon. Baseline ambient light measurements of illumination arriving at the roadway test area are measured in both lighting scenarios. Additionally, the change in illumination on the roadway is recorded at thirty minute intervals as the moon rises to its highest position in the sky. Luminance readings of the roadway objects are recorded during the same time intervals to record the change in reflected light that is attributable to the moon light. In addition to the quantitative measurement of light contribution from the moon during the no moon to full moon transition, observations are made of the change in visibility of objects and pedestrians located on the roadway. To visually document the transition and visibility, calibrated nighttime photography is taken from the driver’s perspective inside a stationery vehicle with low beams activated. These photographs are analyzed after the testing to determine how the light values in the photographs change at each time interval as a result of the addition light contribution from the moon. This analysis includes a discussion of the relative change in aperture settings between the no moon condition and full moon condition represented in the light values in the photographs. A discussion of the conditions under which moon lighting matters for driver visibility is summarized.


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