The quality of the stripe for visibility in daylight or under road lighting is determined by the luminance coefficient under diffuse illumination, Qd, and depends on the materials used, age, and wear pattern. These conditions shall be observed and noted by the user.

Under the same conditions of illumination and viewing, higher levels of Qd correspond to higher levels of lightness.

Reflectivity of pavement (road) markings degrade with traffic wear and require periodic measurement to ensure that sufficient line visibility is provided to drivers.

For a given viewing distance, measurements of Qd made with a reflectometer having a geometry corresponding to that distance are a good indicator of the visual ranking of material measured.

specified by CEN, the measurement geometry of the instrument is based on a viewing distance of 30 m and an eye height of 1.2 m.

It shall be the responsibility of the user to employ an instrument having the specified co-viewing angle.

1.1 This test method covers measurement of the luminance coefficient under diffuse illumination of horizontal pavement markings, such as traffic stripes and surface symbols, and pavement surfaces, in a particular viewing direction using a portable reflectometer.

Note 1—The luminance coefficient under diffuse illumination is a measure of the reflection of horizontal pavement markings and pavement surfaces in a particular viewing direction in daylight or under road lighting. Diffuse illumination approximates daylight illumination from the overcast sky, and road lighting as an average of locations on the pavement surface.

1.2 The co-viewing angle of the reflectometer affects the readings. As specified by the European Committee for Standardization (CEN), the co-viewing angle shall be 2.29°.

1.3 This test method is intended to be used for field measurement of pavement markings and pavement surfaces but may be used to measure the performance of materials on sample panels before placing the marking material in the field.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.