USEFUL CONTRAST INDEX FOR ROADWAY LIGHTING STANDARDS

Abstract

This article proposes a new metric for roadway lighting design that has the potential to improve visibility for drivers during nighttime. The new metric is named as Useful Contrast Index (UCI) and it relates the contrast of obstacles (targets) to the contrast threshold. We define the useful contrast index as the percentage of targets that have a contrast value greater than the contrast threshold along the length of the road. We conclude that the Useful Contrast Index has merit and could be used to provide a better visual environment for drivers.