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U.S. Department of Transportation
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Subject: INFORMATION: Revised Recommended Minimum Maintained Retroreflectivity Levels for Blue and Brown Traffic Signs

From: Michael S. Griffith - Director, Office of Safety Technologies

To: Safety Field, MUTCD Field, Federal Lands Highway Division Engineers

Date: April 5, 2012

In Reply Refer To: HSST

This memorandum supersedes the memorandum dated February 24, 2009 and revises the recommended minimum maintained retrorenectivity levels for white-on-blue signs and white-on-brown signs.

Section 2A.08 of the MUTCD, Maintaining Minimum Rctrorctlectivity of traffic signs allows the option for public agencies to exclude traffic signs with blue or brown backgrounds from the standard. The Federal Highway Administration (FHWA) completed research on recommended minimum retroreflectivity levels for these sign colors in 2008. That research report has recently been corrected after an error was discovered in the reported results for whi te legend on blue background and white legend on brown background rctroretlectivity levels. The amended published research results are shown in the table below:

Minimum maintained recommended retrorejlectivity levels
Sign Color Sheeting Type (ASTM D4956-11a**) Additional
Beading Sheeting Prismatic Sheeting
White on Blue W*; B ≥ 3 W*; B ≥ 5 W*; B ≥ 12 W ≥ 250; B ≥ 12 Overhead
W*; B ≥ 3 W ≥ 120; B ≥ 7 Ground-mounted
White on
W*; Br ≥ 1 W*; Br ≥ 5 W*; Br ≥ 10 W ≥ 350; Br ≥ 10 Overhead
W*; Br ≥ 1 W ≥ 150; Br ≥ 5 Ground-mounted
The minimum retroreflectivity levels shown in this table are in units of cd/lx/m² measured at an observation
angle of 0.2° and an entrance angle of -4.0°.
* This sheeting type should no1 be used for this color for th is applicmion.
** The current version of the specification ASTM D4956-lla combined Types VII, VIII and X as Type VIII.

The complete research report, with errata is avai lable on the Internet at: https://www.fhwa.dot.gov/publications/research/safety/08029/. The FHWA may consider a future rulemaking to amend the MUTCD to include white-on-blue signs and white-on-brown signs. This research will be taken into account if future rulemaking is proposed. However, at this time, the recommended values are not required by regulations. It remains the option of public agencies to consider these recommended minimum maintained retroreflectivity values as they monitor, install and replace white-on-blue signs and white-on-brown signs. If you have further questions, please contact:

Page last modified on October 17, 2012
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