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    Retroreflectivity Degrades Over Time

    When selecting a maintenance process attend to MUTCD language: "Maintenance activities should consider proper position, cleanliness, legibility and daytime and nighttime visibility of a sign."

    Identify your current maintenance approach

    An agency needs to have a process that defines an "adequate" sign and how signs should be maintained. The process must also be consistent with the agency's capabilities and resources. To begin the process, the agency should:(15)
    • Consider current sign maintenance level
    • Determine if nighttime visibility is part of a maintenance plan
    • Consider current visibility of signs at night
    • Recognize if sheeting should be upgraded from ASTM I to ASTM III

    Establish assessment criteria

    Agencies that develop new or improved sign assessment and management programs may lower life cycle costs by fully realizing the service life of installed signs(30). To achieve this potential agencies should consider several factors:
    • Evaluate and compare alternatives for their effectiveness relative to:(15)
      • Accuracy
      • Personnel (manpower)
      • Budget
      • Liability
    • Select a maintenance alternative or combination of alternatives that best meets the agency's circumstances and capabilities(15)
      • . This may include several elements including:(24)
      • Core elements (location, position, sign code MUTCD designation, sign condition, maintenance activities, installation and inspection dates
      • Critical elements (dimensions, sheeting type, sign blank type, post/support type and condition, sign orientation, posted speed limit at the time activities were conducted
      • Desirable elements (offset, height, retroreflectivity, inspector name, sign ID if different from MUTCD designation, images of sign, comments, other reference numbers
      • Data collection approach
      • Inventory maintenance approach
    If the agency does not have sufficient in-house resources or expertise to conduct a competent field analysis, subcontract these services to a design/build or traffic engineering agency. It is important to develop an accurate representation across the entire inventory quickly to determine the most cost-effective change-out on a needs basis.(15)

    Recognize minimums and reflective materials(29)

    Most sign faces are made with retroreflective sheeting which gradually deteriorates over time making signs less visible at night and no longer meeting the driver's needs. Deterioration and damage must be noticed and signs replaced before they reach retroreflectivity minimums.


    15 Traffic sign retroreflectivity "sign retro 101", FHWA Visibility Team PowerPoint
    24 Inventory systems for traffic control devices (2001) found on http://www.ctre.iastate.edu/PUBS/itcd/inventory.pdf
    29 Notice of proposed amendment: maintaining traffic sign retroreflectivity; FHWA Office of Safety Retroreflectivity Team PowerPoint
    30 Maintaining traffic sign retroreflectivity: impacts on state and local agencies, FHWA-HRT-07-042
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