Retroreflectivity Maintenance
Visual Nighttime Inspection Method
In the visual nighttime inspection method, agency personnel assess the nighttime visibility of their signs. The visual inspection method is probably the most consistent with current practices at many agencies. Visual inspections are also recommended in Section 2A.22 of MUTCD.
In the visual inspection method, the inspector assesses the visibility and retroreflectivity of the traffic signs as he/she approaches the signs. Signs need to be replaced if they do not meet the comparison defined in the appropriate procedure. The following recommendations provide general guidance on how to conduct the inspections:
- Agencies develop guidelines and procedures for inspectors to use in conducting the nighttime inspections. Inspectors are trained on the use of these procedures.
- The inspection is conducted at normal roadway operating speeds. If it is necessary to slow or stop the vehicle to read the sign, the sign typically needs to be replaced. Signs are normally inspected from the travel lane.
- The inspection is conducted using the low beam headlights.
- Signs are normally evaluated at a typical viewing distance for each sign, one that provides a driver with adequate time for an appropriate response.
In addition to the above, one or more of the following procedures are used in conducting visual nighttime inspections.