Assessment of Durability of Wet Night Visible Pavement Markings

Abstract

This paper describes the visibility experiment conducted as part of a research effort to establish the durability of pavement markings in an on-road installation. Six marking technologies were installed on a portion of Route 460 in Blacksburg, Virginia. A human factors experiment in natural rain conditions was performed to establish the visibility needs of the driver. The retroreflectivity of the markings was measured at intervals of 2 to 5 months, with six measurements over the course of 23 months (these data are discussed in a separate paper). Previous research suggested that a minimum retroreflectivity of 150 mcd/m²/lx should be maintained to meet drivers' visibility needs. As part of this research, a human factors experiment was conducted to test the validity of this recommendation. The distance at which participants could detect the end of a pavement marking was measured as well as the retroreflectivity of the marking at those points. The relationship of detection distance and retroreflectivity found in this study suggests that as retroreflectivity increases beyond 150 mcd/m²/lx, there are diminishing returns on detection distance. This finding suggests that the recommended minimum is appropriate for providing increased visibility for drivers, while keeping retroreflectivity requirements at a reasonable level for marking manufacturers.