Evaluation Of Wet Weather Pavement Markings

This report details the first year of a two-year project. During the first year the emphasis was on determining the wet-night visibility of various pavement marking systems under a variety of realistic rainfall levels. The researchers performed a literature review. They analyzed 20 years of Texas rainfall data to determine the most appropriate rainfall levels to use as design criteria for a rain tunnel. Using a low, medium, and high rainfall rate (0.28, 0.52, and 0.87 in. per hour, respectively), a 1600 ft long rain tunnel was designed and built at Texas A & M University's Riverside Campus. Experimental subjects drove through the rain tunnel and looked for pavement markings simulating skip lines. The researchers rotated pavement marking samples at different locations before each trial. The detection distance was recorded when the subject located the pavement marking sample. The data were analyzed in four main sections: waterborne paints, thermoplastics, tapes, and exotic materials. The analysis also included investigations into the wet-night visibility of rumble stripes, as well as wider lines. The measured dry and wet retroreflectivity measurements were analyzed, and the predictive capabilities of the wet retroreflectivity measurements were evaluated with respect to the wet-night detection distance of the markings.