Traffic Sign Retroreflectivity: Basics of Sign Retroreflectivity & New Sign Maintenance Requirements [PDF 5.21 MB, PPT 22.4 MB]
Intended for managers and decision-makers, this course describes sign retroreflecivity concepts and summarizes new Federal requirements. After taking the course, participants will understand nighttime visibility issues and be able to describe retroreflectivity maintenance methods.
Conducting Sign Retroreflectivity Inspections
This course is designed for field personnel who are responsible for sign maintenance, including maintenance of sign retroreflectivity. The course focuses on assessment techniques for conducting sign maintenance inspections to evaluate retroreflectivity.
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Minimum Retroreflectivity Levels for Blue and Brown Traffic Signs [HTML, PDF 1 MB]
This report provides research findings supporting recommendations for minimum maintained retroreflectivity (MR) levels for white-on-blue and white-on-brown signs. The report also includes findings of an investigation of MR levels needed for complex visual conditions, such as glare from oncoming headlamps and fixed roadway lighting. FHWA-HRT-08-029.
Minimum Retroreflectivity Levels for Overhead Guide Signs and Street-Name Signs [HTML, PDF 837 KB]
This 2003 report prepared for the FHWA by Texas Transportation Institute presents the results of a study that investigated the nighttime visibility needs of drivers for viewing overhead guide sign and street name signs. FHWA-RD-03-082.
Updated Minimum Retroreflectivity Levels for Traffic Signs [HTML, PDF 837 KB]
This 2003 report prepared by Texas Transportation Institute for the FHWA updates the minimum levels of traffic sign retroreflectivity for certain types of traffic signs (regulatory, guide, and warning), which were originally generated in 1993. FHWA-RD-02-081.
Maintaining Traffic Sign Retroreflectivity: Impacts on State and Local Agencies [HTML, PDF 417 KB]
This 2007 report prepared by the FHWA’s Turner Fairbank Highway Research Center analyzes the administrative, fiscal, implementation, and tort liability concerns of State and local transportation agencies in relation to the adoption of minimum maintained retroreflectivity levels for traffic signs. The results are based on input received at four workshops held during the summer of 2002. FHWA-HRT-07-042
Workshops on Nighttime Visibility of Traffic Signs: Summary of Workshop Finding
This report presents the results of four workshops sponsored by the FHWA in 2002 to obtain input from stakeholders regarding the issues and alternatives associated with minimum levels of in-service sign retroreflectivity. About 100 invited representatives attended the workshops, including city, county, and State transportation agencies, professional organizations, agency attorneys, and FHWA staff.
Turner-Fairbank Photometric and Visibility Laboratory
The FHWA Turner-Fairbank Highway Research Center’s Arens Photometric and Visibility Laboratory (PVL) enables researchers to evaluate the photometric and colorimetric properties of signing and marking materials, including fluorescent materials. Studies of human-centered systems related to visibility issues are also performed in this laboratory.
Retroreflectivity Research Bibliography
Click here for a list of additional reports and research related to retroreflectivity.
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FHWA Resource Charts, July 2013
FHWA Roadway Lighting Handbook, August 2012
RwD Strategic Plan, April 2013
Updated Guidance on Sign Retroreflectivity, April 2013
Clarifying Guidance on Daytime Luminance, January 2013
Guidance for the Selection , Use and Maintenance of Cable Barrier Systems, November 2012