Why Are Road Signs So Reflective?

Unlike other shiny surfaces, which reflect light according to the angle of the light emitting source, road signs are designed to reflect light in all directions, no matter what angle the source of the light is approaching from (as long as it reaches the sign). This makes them more visible from any and every direction.

This type of reflectiveness is called “retroreflection,” and it is achieved by manufacturing road signs with a coating of prismatic reflectors or glass beads on the sign’s surface.

Retroreflective road signs are repaired and replaced regularly in order to maintain a high standard of brightness and visibility, as it is normal for the reflective coating to degrade over time.