Nighttime Visibility and Retroreflectance of Pavement Markings in Dry, Wet, and Rainy Conditions

Abstract

Research was conducted to determine the nighttime visibility of flat pavement-marking tape, patterned pavement-marking tape, and wetweather pavement-marking tape in dry, wet (just after rainfall), and simulated rain conditions (ongoing 1-in./h rainfall). The measures of effectiveness were the detection distances, the eye-fixation distributions, and the pavement-marking retroreflectance. The research was sponsored by FHWA. The experiment was conducted on a test track in Cottage Grove, Minnesota. This test track had a section at which 1-in./h rainfall could be simulated. Eleven women and seven men, ranging in age from 55 to 74 (average age 62.5), participated in this study. The participants drove the experiment vehicles along the pavement-marking treatments. The participants were to state the earliest point at which they could see the end of the pavement markings. The retroreflectance of each pavement-marking material was measured with three handheld retroreflectometers under the three weather conditions according to ASTM E-1710 (dry), ASTM E-2177 (wet recovery), and ASTM E-2176 (continuous wetting). The retroreflectance values were correlated to the detection distances to determine the ability of each ASTM test method to predict visibility performance under the corresponding weather condition. The wet-weather tape performed best for detection distance, followed by the patterned tape and the flat tape. The detection distances were longest in the dry condition, shorter in the wet condition, and shortest in the simulated rain condition.