What factors affect the retroreflective luminance coefficient measured on-site?

Using a portable retroreflectometer to measure reflective markings, what factors influence the measured retroreflection coefficient during on-site inspections?

When testing reverse reading readings on-site, numerous factors can cause variations.

1. Slight changes in the position of the retroreflectometer on traffic reflective markings can result in different readings.

2. Horizontal lines can produce readings that are more uneven than vertical lines. The horizontal lines show greater wear in the wheelbase area and less wear in non-wheelbase areas.

3. The refractive index of the glass beads, their embedding depth, and the application rate on road markings will all affect the reading.

4. The adhesive in the coating, the amount of pigment added, the application condition, as well as dust, salt, dirt, and water can also affect the readings.

5. The incidence angle on the test surface will be affected by the degree of flatness of the reflective markings.