Introduction
Pavement-marking retroreflectorization is accomplished through the use of glass beads partially embedded on the surface of the marking binder material. Glass beads play the most important role in pavement-marking retroreflectivity. Markings without beads are virtually useless at night. The bead returns light from a headlamp back to a driver, as shown in Figure 2-17.

Figure 2-17. 2-17. Pavement-marking retroreflectivity using glass beads.