All signs, including supports, should be inspected twice a year for:

One of the two annual inspections should be conducted at night to check legibility and retroreflectivity (see following subheading).

Inspections should be made by two persons, so one can take notes while the other drives.

All personnel who frequently travel the highways should be instructed to report any obscured or damaged signs. Maintenance personnel should be alert at all times, observing signs for legibility, position, and minor damage for which immediate remedial action can be taken.