An investigation into the predictive performance of pavement marking retroreflectivity measured under various conditions of continuous wetting

摘要

This thesis research investigated the predictive performance of pavementmarking retroreflectivity measured under various conditions of continuous wetting. Theresearcher compared nighttime detection distance of pavement markings in simulatedrain conditions and the retroreflectivity of the same pavement markings in severalcontinuous wetting conditions. Correlation analyses quantified the predictiveperformance of the resulting retroreflectivity values from the continuous wettingconditions.The researcher measured the retroreflectivity of 18 pavement marking samplesunder 14 different conditions. The American Society for Testing and Materials (ASTM)has three standards for measuring the retroreflectivity of pavement markings under:dry (E-1710), recovery (E-2177), and continuous wetting conditions (E-2176). Usingthree ASTM standard conditions resulted in three sets of retroreflectivity data, andvariations of the continuous wetting standard produced an additional 11 sets ofcontinuous wetting condition data.The researcher also incorporated detection distance values measured for thesame 18 pavement marking samples under three different simulated rainfall conditions at night. The three conditions included: high (0.87 in/hr), medium (0.52 in/hr), and low(0.28 in/hr) flow rates, these rates were to simulate typical rainfall rates in the state ofTexas.The correlation analyses measures the linear relationship as well as thelogarithmic relationship between the detection distance and the retroreflectivity of thepavement markings. A pavement markings' retroreflectivity is typically used as adetection distance performance indicator, therefore a high degree of correlation betweenretroreflectivity and detection distance would be desired. A high degree of correlationwould indicate that a measured retroreflectivity value of a pavement marking wouldprovide a good indication of the expected detection distance.The researcher conducted analyses for several subgroups of the pavementmarkings based on the markings type or characteristics. Dry, recovery, and all thecontinuous wetting retroreflectivity data were correlated to the detection distances.Correlation values found during this thesis research did not show a high degree ofcorrelation for most of the subgroups analyzed. This indicates that measuredretroreflectivity would not provide very good predictive performance of the pavementmarkings detection distance in rainy conditions.