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This report is an archived publication and may contain dated technical, contact, and link information
Publication Number: FHWA RD-03-081
Date: June 2003

Updated Minimum Retroreflectivity Levels

Final Report

PDF Version (837 KB)

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The following retroreflectivity resolution was passed by the AASHTO Board of Directors at its Annual Meeting in December 2000.




WHEREAS, the American Association of State Highway and Transportation Officials (AASHTO) is aware of the congressional mandate for the Secretary of Transportation to revise the Manual on Uniform Traffic Control Devices to include a standard for the minimum level of retroreflectivity that must be maintained for pavement markings and signs, which shall apply to all roads open to public travel, and

WHEREAS, AASHTO concurs that it is desirable to maintain an adequate level of retroreflectivity for both traffic signs and pavement markings to enhance safety for motorists during hours of darkness and during adverse weather conditions, and

WHEREAS, AASHTO is concerned about additional liability for transportation agencies if the Federal Highway Administration (FHWA) establishes the proposed minimum levels of retroreflectivity, and

WHEREAS, AASHTO greatly appreciates the opportunity afforded by FHWA to consider recommendations from AASHTO prior to publishing proposed rule making for MR for both signs and pavement markings;

THEREFORE, AASHTO established a "Task Force on Retroreflectivity Guidelines" composed of members from federal, state, and local transportation agencies, and from several transportation and industry associations, and has studied the various issues and produced a report with recommendations; and

THEREFORE, BE IT RESOLVED that based upon the findings and recommendations of the Task Force, AASHTO agrees that:

  • It is desirable to assure adequate night visibility of traffic signs.
  • Regular assessments of the adequacy of retroreflectivity or the planned replacements of signs to assure adequate night visibility is necessary.

BE IT FURTHER RESOLVED that efforts to assure adequate night visibility should not impose undue burdens on highway agencies, and to that end, AASHTO recommends that FHWA consider the following:

  1. The minimum requirements need to be presented in a simple and unambiguous format to assure that they can be easily and properly applied
  2. Tables defining MR requirements should not appear in the MUTCD to help protect agencies from unnecessary tort liability.
  3. Alternative methods to assess night visibility need to be fully developed
  4. Agencies should have the option to select the methods or combination of methods best suited to their needs and resources.
  5. Agencies should have a 6-year period to implement methods.

FURTHER, it should be noted that the AASHTO Task Force on Retroreflectivity Guides will evaluate forthcoming FHWA findings and recommendations relative to MR values for additional types of signs and for pavement markings as they become available, and will provide comments at that time

FHWA editorial note:

The four methods in Number 4 in the resolution are for evaluation processes and are briefly described as follows:

  1. Measure sign retroreflectivity with instruments and compare to numeric values in tables.
  2. Conduct nighttime sign inspections and compare sign legibility distances to distance values in a table.
  3. Conduct nighttime sign inspections by trained observers that would know how to subjectively evaluate signs
  4. Knowing how long certain retroreflective materials last in a certain geographic area, replace signs on a schedule to insure replacement prior to the sign reaching the end of its service life.

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