Maintaining Traffic Sign Retroreflectivity: Impacts on State and Local Agencies PUBLICATION NO. FHWA-HRT-07-042 APRIL 2007 U.S. Department of Transportation Federal Highway Administration Research, Development, and Technology Turner-Fairbank Highway Research Center 6300 Georgetown Pike McLean, VA 22101-2296 FOREWORD In 1992, the Congress directed the Secretary of Transportation to revise the Manual on Unifrom Traffic Control Decives to include a standard for minimum levels of retroreflectivity that must be maintained for traffic signs. The FHWA already had an active research program investigating the nighttime visibility of traffic signs, and responded to the congressional mandate by publishing a set of recommendations for minimum maintained sign retroreflectivity levels in October 1993. An analysis of the impacts of the proposed minimum maintained traffic sign retroreflectivity levels was published in April 1998. The following document updates the 1998 report on the national impact of minimum maintained traffic sign retroreflectivity levels, and addresses concerns expressed in four FHWA-sponsored workshops that were held in 2002. The primary sources of information for this effort are previous studies related to the benefits of improved signage and the impacts of implementing sign system upgrades. This report will be of interest to State and local agencies with responsibility for traffic signs and people involved in traffic sign maintenance. Michael F. Trentacoste Director, Office of Safety Research and Development Notice This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in this document. The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers’ names appear in this report only because they are considered essential to the objective of the document. Quality Assurance Statement The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement. TECHNICAL REPORT DOCUMENTATION PAGE 1. Report No. 2. Government Accession No. 3. Recipient’s Catalog No. FHWA-HRT-07-042 4. Title and Subtitle 5. Report Date Maintaining Traffic Sign Retroreflectivity: Impacts on State and Local April 2007 Agencies 6. Performing Organization Code FHWA HRDS-05 7. Author(s) 8. Performing Organization Report No. Kenneth S. Opiela, PE, PhD Carl K. Andersen 9. Performing Organization Name and Address 10. Work Unit No. Turner-Fairbank Highway Research Center 6300 Georgetown Pike 11. Contract or Grant No. McLean, VA 22101-2296 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered Office of Safety R&D Federal Highway Administration 14. Sponsoring Agency Code 6300 Georgetown Pike McLean, VA 22101-2296 15. Supplementary Notes 16. Abstract This report analyzes the impacts that might be expected from the adoption of proposed minimum maintained retroreflectivity levels for traffic signs to improve night visibility. The report evaluates the broad spectrum of concerns expressed by State and local agency staff at four workshops held during the summer of 2002. These include administrative, fiscal, implementation, and tort liability concerns. The report includes a summary of previous studies, including those of several State agencies, to determine the impacts of the proposed new minimum maintained levels for traffic sign retroreflectivity. The various sign cost elements are identified and changes attributable to the new minimum levels of retroreflectivity are isolated. The cost of sign face materials is seen as the major source of increased costs. The cost impact is determined to be a function of the condition of existing signs, State and local agency practices on the use of sign materials, and current procedures for sign management. The report provides estimates of the National impact of the proposed minimum levels generated by the models previously developed using updated inputs for sign material costs and road mileage. It was assumed that the distribution of non-compliant signs has remained the same. Estimates of the costs for upgrading street name and overhead guide signs were also generated to cover the full spectrum of signs covered by the proposed minimum levels. National sign replacement costs incurred as a result of proposed minimum maintained retroreflectivity levels are estimated to be $37.5 million. Using a 7-year implementation period for regulatory, warning, and guide signs and a 10-year implementation period for street name and overhead guide signs, the annual impacts are estimated to be $4.5 million for years 1 through 7 and $2.1 million for years 8 through 10. The estimates are based upon the added cost of higher performance sign materials, with the majority of sign replacements conducted as part of normal sign maintenance cycles. The labor, equipment, and mileage costs for sign replacement were excluded under the assumption that the proposed implementation period was long enough to allow replacement of non-compliant signs under reasonable maintenance cycles. The report concludes that there will be increases in the costs to agencies resulting from the need to use more expensive sign face materials to increase retroreflective performance, but there should be no impacts on the costs of other sign elements. Agencies may experience a reduction in service life costs because of the longer service life of the improved sign face materials. 17. Key Words 18. Distribution Statement retroreflectivity, maintained retroreflectivity, minimum maintained No restrictions retroreflectivity, impact, impact assessment, impacts analysis, national impact assessment 19. Security Classification (of this 20. Security Classification (of 21. No of Pages 22. Price report) this page) 38 Unclassified Unclassified Form DOT F 1700.7 (8-72) Reproduction of completed pages authorized SI* (MODERN METRIC) CONVERSION FACTORS APPROXIMATE CONVERSIONS TO SI UNITS Symbol When You Know Multiply By To Find Symbol LENGTH in inches 25.4 millimeters mm ft feet 0.305 meters m yd yards 0.914 meters m mi miles 1.61 kilometers km AREA in2 square inches 645.2 square millimeters mm2 ft2 square feet 0.093 square meters m2 yd2 square yard 0.836 square meters m2 ac acres 0.405 hectares ha mi2 square miles 2.59 square kilometers km2 VOLUME fl oz fluid ounces 29.57 milliliters mL gal gallons 3.785 liters L ft3 cubic feet 0.028 cubic meters m3 yd3 cubic yards 0.765 cubic meters m3 NOTE: volumes greater than 1000 L shall be shown in m3 MASS oz ounces 28.35 grams g lb pounds 0.454 kilograms kg T short tons (2000 lb) 0.907 megagrams (or "metric ton") Mg (or "t") TEMPERATURE (exact degrees) oF Fahrenheit 5 (F-32)/9 Celsius oC or (F-32)/1.8 ILLUMINATION fc foot-candles 10.76 lux lx fl foot-Lamberts 3.426 candela/m2 cd/m2 FORCE and PRESSURE or STRESS lbf poundforce 4.45 newtons N lbf/in2 poundforce per square inch 6.89 kilopascals kPa APPROXIMATE CONVERSIONS FROM SI UNITS Symbol When You Know Multiply By To Find Symbol LENGTH mm millimeters 0.039 inches in m meters 3.28 feet ft m meters 1.09 yards yd km kilometers 0.621 miles mi AREA mm2 square millimeters 0.0016 square inches in2 m2 square meters 10.764 square feet ft2 m2 square meters 1.195 square yards yd2 ha hectares 2.47 acres ac km2 square kilometers 0.386 square miles mi2 VOLUME mL milliliters 0.034 fluid ounces fl oz L liters 0.264 gallons gal m3 cubic meters 35.314 cubic feet ft3 m3 cubic meters 1.307 cubic yards yd3 MASS g grams 0.035 ounces oz kg kilograms 2.202 pounds lb Mg (or "t") megagrams (or "metric ton") 1.103 short tons (2000 lb) T TEMPERATURE (exact degrees) oC Celsius 1.8C+32 Fahrenheit oF ILLUMINATION lx lux 0.0929 foot-candles fc cd/m2 candela/m2 0.2919 foot-Lamberts fl FORCE and PRESSURE or STRESS N newtons 0.225 poundforce lbf kPa kilopascals 0.145 poundforce per square inch lbf/in2 *SI is the symbol for the International System of Units. Appropriate rounding should be made to comply with Section 4 of ASTM E380. (Revised March 2003) ii TABLE OF CONTENTS TECHNICAL REPORT DOCUMENTATION PAGE.............................................................. i PREFACE...................................................................................................................................... 1 1. INTRODUCTION................................................................................................................. 2 1.1. System of Traffic Signs................................................................................................. 2 1.2. Night Visibility of Traffic Signs................................................................................... 2 1.3. Purpose of Retroreflectivity......................................................................................... 2 1.4. Traffic Sign Degradation.............................................................................................. 3 1.5. Minimum Maintained Retroreflectivity ..................................................................... 3 1.6. Impacts of Proposed Rule ............................................................................................ 3 1.7. Benefits of Improved