Which material property enhances the visibility of road signs at night?

The property that enhances the visibility of road signs at night is reflectivity. Reflectivity refers to the ability of a surface to reflect light, which is particularly important for road signs that need to be seen in low-light conditions, such as during nighttime or inclement weather. Signs made with reflective materials can bounce back the headlights of approaching vehicles, making them much more visible to drivers. This visibility is crucial for ensuring safety on the roads, as it allows drivers to identify warnings, directions, and information well in advance.

Other properties, such as color saturation, bring their own advantages in terms of daytime visibility, but without reflectivity, signs would be much harder to see at night when visibility is at its lowest. Size can also play a role, influencing how far away a sign can be recognized, but is not as critical as the ability to reflect light in dark conditions. Material weight does not directly impact visibility; rather, it may affect the sign's durability or installation process but has no effect on how well the sign can be seen at night.