ASTM E2177-20

4.1 The nighttime performance of pavement markings is determined by the coefficient of retroreflected luminance, 4.2 Under the same conditions of headlight illumination and driver’s viewing, larger values of 4.3 The pavement marking’s measured performance in the condition of wet recovery is used to characterize the performance of the marking on the road when wet.

4.4 Newly installed pavement markings may have a natural surface tension or release agents that prevent wetting of the product by water. The water will tend to “bead up” on the marking. This “non wetting” condition is usually short lived. Pavement markings that have been on the road for one month prior to testing usually do not exhibit this non-wetting phenomenon. (Warning—This phenomenon produces an interference when assessing the wet characteristics of a pavement marking. Attempts to measure markings with this surface “non-wetting” or “beading” of the water may give higher values.)

4.5 The retroreflectivity, R_L, of pavement (road) markings degrades with traffic wear and requires periodic measurement to ensure that sufficient line visibility is provided to drivers.

4.6 For a given viewing distance, measurements of 4.7 As specified by Test Method E1710, the measurement geometry of the instrument is based on a viewing distance of 30 m, an eye height of 1.2 m and a headlight mounting height of 0.65 m (see Appendix X1).

4.8 It shall be the responsibility of the user to employ an instrument having the specified observation and entrance angles.

1.1 This test method covers the measurement of the wet retroreflective (R_L) properties of horizontal pavement marking materials, such as traffic stripes and road surface symbols, using a portable retroreflectometer that can be placed on or before the road marking to measure the retroreflection at the prescribed geometry.

1.2 This method of measuring the wet retroreflective properties (R_L) of pavement markings measures the wet retroreflectivity in a condition of wet recovery (see Fig. 1).