Minnesota Department of Transportation

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Sign Retroflectivity


Orange barrels on a highway

Traffic Sign Life Expectancy Project (LRRB INV 943)

The Minnesota Local Road Research Board funded this project to develop new expected sign life values. This will enable local agencies to better manage their traffic sign assets and decrease their costs by enabling more efficient sign replacement strategies.

Project Goals

  • Develop sign life expectancies for sheeting materials used in Minnesota
  • Identify the common drivers of sign replacements
  • Provide guidance to local agencies on adoption of sign maintenance policies

Project Schedule (Revision #1, 04/14)

Task 1: Survey of Practice, April 30th, 2013
Task 2: Test Deck & Data Collection Plan, June 30th, 2013
Task 3: MnROAD Data Collection, FY 2013-2014
Task 4: MnROAD Data Collection, FY 2015
Task 5: MnROAD Data Collection, FY 2016-2017
Task 6: System Data Collection, December 30th, 2013
Task 7: Data Analysis, Recommendations, Report June 30th, 2014

Sign Life Expectancy Guidance

Project Final Report at LRRB website

Project Presentations

Tap Meeting - May 2014
Tap Meeting - March 2014
Tap Meeting - August 2013
Tap Meeting May - 2013
Tap Meeting - February 2013

Resources and Literature

Minnesota State Aid Traffic Safety Page
Federal Manual on Uniform Traffic Control Devices
Minnesota Manual on Uniform Traffic Control Devices
Minnesota's Best Practices for Traffic Sign Maintenance/Management Handbook
NCHRP Synthesis 431: Practices to Manage Traffic Sign Retroflectivity

Minnesota Sign Life Database

a. Preliminary 2013 Retroreflectivity Data
b. MnROAD test deck data summary (Updated Nov. 2016) 
c. Color and Retroreflectivity Data for New Sign Panels on Test Deck (Updated Nov. 2016) 
d. Retroreflectivity Data for Salvaged Sign Panels on Test Deck (Updated Nov. 2016) 
e. Detailed List of All Salvaged Panels on Test Deck (Updated Nov. 2016) 

MnDOT Sign Test Deck - Layout and Photos

MnROAD Sign Retro Test Deck As-Built Plan
Test Deck Photos 1 I 2 I 3 I 4

Resources for Project Participants

Example Retro Data Collection Worksheet