Field Surveys of Pavement-Marking Retroreflectivity

Abstract

Field surveys of pavement-marking retroreflectivity were conducted throughout the United States. Thirty-two state and local highway agencies participated in the study by identifying pavement-marking sites for measurement. The retroreflectivity of both white and yellow pavement-marking lines of six different marking materials—conventional paint, waterborne paint, epoxy, polyester, thermoplastic, and tape—was measured in the field. Field measurements of pavement-marking retroreflectivity for sites under the jurisdiction of all 32 participating agencies were made in the fall of 1994. Selected sites were remeasured in the spring of 1995 for six of the participating agencies. All field measurements were made with a Retrolux Model 1500 retroreflectometer. A comparison of the fall 1994 and spring 1995 results are presented. Data analyses were conducted to determine the mean, standard deviation, and distribution of the coefficient of retroreflected luminance (retroreflectivity) and the contrast ratio between the retroreflectivity of the pavement markings and that of the adjacent pavement surface by color of line and pavement marking material. However, it was difficult to state any definitive comparisons between material types without knowing the relative ages and manufacturers of the markings, and such data were unavailable. The economic implications of particular threshold values for replacement of pavement markings were also evaluated.