Recommended Procedures for Testing and Evaluating Detectable Warning Systems (2010)

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TRANSPORTAT ION RESEARCH BOARD WASHINGTON, D.C. 2010 www.TRB.org N A T I O N A L C O O P E R A T I V E H I G H W A Y R E S E A R C H P R O G R A M NCHRP REPORT 670 Subscriber Categories Pedestrians and Bicyclists • Safety and Human Factors Recommended Procedures for Testing and Evaluating Detectable Warning Systems Thomas J. Rowe Kimberly Steiner John Lawler Jonah Kurth WISS, JANNEY, ELSTNER ASSOCIATES, INC. Northbrook, IL Research sponsored by the American Association of State Highway and Transportation Officials in cooperation with the Federal Highway Administration

NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed research provides the most effective approach to the solution of many problems facing highway administrators and engineers. Often, highway problems are of local interest and can best be studied by highway departments individually or in cooperation with their state universities and others. However, the accelerating growth of highway transportation develops increasingly complex problems of wide interest to highway authorities. These problems are best studied through a coordinated program of cooperative research. In recognition of these needs, the highway administrators of the American Association of State Highway and Transportation Officials initiated in 1962 an objective national highway research program employing modern scientific techniques. This program is supported on a continuing basis by funds from participating member states of the Association and it receives the full cooperation and support of the Federal Highway Administration, United States Department of Transportation. The Transportation Research Board of the National Academies was requested by the Association to administer the research program because of the Board’s recognized objectivity and understanding of modern research practices. 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Research projects to fulfill these needs are defined by the Board, and qualified research agencies are selected from those that have submitted proposals. Administration and surveillance of research contracts are the responsibilities of the National Research Council and the Transportation Research Board. The needs for highway research are many, and the National Cooperative Highway Research Program can make significant contributions to the solution of highway transportation problems of mutual concern to many responsible groups. The program, however, is intended to complement rather than to substitute for or duplicate other highway research programs. Published reports of the NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM are available from: Transportation Research Board Business Office 500 Fifth Street, NW Washington, DC 20001 and can be ordered through the Internet at: http://www.national-academies.org/trb/bookstore Printed in the United States of America NCHRP REPORT 670 Project 4-33 ISSN 0077-5614 ISBN 978-0-309-15506-9 Library of Congress Control Number 2010936777 © 2010 National Academy of Sciences. All rights reserved. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMCSA, FTA, or Transit Development Corporation endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. NOTICE The project that is the subject of this report was a part of the National Cooperative Highway Research Program, conducted by the Transportation Research Board with the approval of the Governing Board of the National Research Council. The members of the technical panel selected to monitor this project and to review this report were chosen for their special competencies and with regard for appropriate balance. The report was reviewed by the technical panel and accepted for publication according to procedures established and overseen by the Transportation Research Board and approved by the Governing Board of the National Research Council. The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research and are not necessarily those of the Transportation Research Board, the National Research Council, or the program sponsors. The Transportation Research Board of the National Academies, the National Research Council, and the sponsors of the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturers’ names appear herein solely because they are considered essential to the object of the report.

CRP STAFF FOR NCHRP REPORT 670 Christopher W. Jenks, Director, Cooperative Research Programs Crawford F. Jencks, Deputy Director, Cooperative Research Programs Amir N. Hanna, Senior Program Officer Eileen P. Delaney, Director of Publications Natalie Barnes, Editor NCHRP PROJECT 4-33 PANEL Field of Materials and Construction—Area of General Materials Peter Kemp, Wisconsin DOT, Madison, WI (Chair) Norie Calvert, Maryland State Highway Administration, Baltimore, MD Dennis Cannon, Synergy, LLC, Washington, DC (formerly United States Access Board) Kenneth R. Cooper, Kenneth Cooper Engineering, PLLC, Hendersonville, NC (formerly Arizona DOT) Cindy Estakhri, Texas A&M University, College Station, TX Peter B. Krause, Texas DOT, Austin, TX Henry W. Lacinak, AASHTO, Baton Rouge, LA (formerly Louisiana DOTD) Christopher M. Newman, FHWA Liaison Richard Pain, TRB Liaison AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under NCHRP Project 4-33 by Wiss, Janney, Elstner Asso- ciates, Inc. (WJE). Mr. Thomas J. Rowe, P.E., Senior Consultant, was the Principal Investigator. The authors of this report are Kimberly Steiner, Senior Associate; Dr. John Lawler, Senior Associate; and Jonah Kurth, Associate II, of WJE. The authors thank James Connolly, John Fraczek, and Paul Krauss of WJE for their helpful input. C O O P E R A T I V E R E S E A R C H P R O G R A M S

This report presents a set of recommended test methods for evaluating durability of detectable warning systems. These methods address exposure regimes, test procedures, and evaluation criteria to help select detectable warning systems that provide long-term perfor- mance and durability while meeting the requirements of the Americans with Disabilities Act Accessibility Guidelines (ADAAG). The test methods are presented in AASHTO format to facilitate consideration and incorporation into the AASHTO Standard Specifications for Transportation Materials and Methods of Sampling and Testing. The material contained in the report should be of immediate interest to state materials engineers and those concerned with the different aspects of the ADAAG. Since 2001, the Americans with Disabilities Act Accessibility Guidelines (ADAAG) have required placement of detectable warnings on curb ramps, which remove a tactile cue oth- erwise provided by curb faces, and at other areas where pedestrian ways blend with vehicu- lar ways. The ADAAG defines a detectable warning as “a standardized surface feature built in or applied to walking surfaces or other elements to warn visually impaired people of haz- ards on a circulation path.” The ADAAG further provides geometric requirements for trun- cated domes and stipulates a visual contrast with adjacent walking surfaces. To accommo- date these requirements, detectable warning surfaces (e.g., plastics, ceramics, brick and concrete pavers, and metal) have been developed. These systems are expected to provide long-term performance and durability by maintaining geometric characteristics, frictional properties, and other functional requirements over the expected service life. These perfor- mance considerations are influenced by material properties and conditions of use, includ- ing climate (e.g., temperature ranges, sun exposure, and snowfall), maintenance practices (e.g., snow removal, use of deicing chemicals, and sweeping), type and condition of under- lying surface (e.g., underlying material types, texture, and distress), construction methods (e.g., surface preparation and use of adhesives), and other factors. The ADAAG and recent research focused on detectability; limited attention was given to material requirements that influence long-term performance and durability or the test pro- cedures needed for evaluating detectable warning systems. Thus research was needed to (1) identify the long-term performance and durability requirements and related properties of detectable warning systems, (2) recommend test methods for evaluating detectable warn- ings, and (3) develop guidance on the use of these methods for selecting detectable warn- ing systems that will provide long-term performance and durability for different conditions while meeting the requirements of the ADAAG. Under NCHRP Project 4-33, “Procedures for Testing and Evaluating Detectable Warn- ing Systems,” Wiss, Janney, Elstner Associates, Inc. of Northbrook, Illinois, worked with the F O R E W O R D By Amir N. Hanna Staff Officer Transportation Research Board

objectives of recommending test methods for evaluating performance and durability aspects of detectable warning systems and providing guidance on the use of these methods for selecting detectable warning systems for specific conditions of use. The research focused on material requirements and did not deal with detectability or geometric compliance requirements. The research included a review of the existing information relevant to detectable warn- ing system designs, materials, durability, and testing. As part of this review, information on commonly used products, deterioration mechanisms, and performance was obtained through a survey of state and municipal departments of transportation. The important properties for functional performance of detectable warning systems are color contrast, slip resistance, mechanical integrity, and dimensional stability. Degradation mechanisms that affect these aspects of functional performance are freezing and thawing, abrasion, ultravio- let radiation, moisture, extreme temperatures, as well as physical stresses caused by impact, snow removal, and foot and vehicular traffic. The research also included an extensive laboratory testing program to evaluate the effects of specific exposure regimes on detectable warning systems and to develop test methods for evaluating durability of these systems. These exposure regimes covered a range of freeze- thaw, high temperature thermal cycling, ultraviolet exposure, and abrasion exposure. The evaluations included visual and microscopic examination, color measurement, dome shape and geometry measurement, slip resistance, coating and single dome bond, resistance to impact from falling objects, wear resistance, and resistance to impact from simulated snow- plow operations. These exposures were combined and performed cyclically to better simu- late the effects of in-service exposure. Test results provided the basis for the recommended set of thirteen tests. The research also provided guidance on the use and interpretation of the test results to help select those systems that will provide long-term performance and durability when used under specific environmental conditions. The appendix contained in the research agency’s final report provides further elabora- tion on the work performed in this project. This appendix titled “Research Leading to the Development of Methodology for Durability Assessment of Detectable Warning Systems” is not published herein; but is available on the NCHRP Report 670 summary web page at http://www.trb.org/Main/Blurbs/163989.aspx.

C O N T E N T S 1 Summary 3 Chapter 1 Background 3 Detectable Warning Systems Performance and Deterioration Mechanisms 5 Objectives and Scope of Completed Research 5 Organization of Project Documents 6 Chapter 2 Research Approach 6 Summary of Tasks 6 Phase I Approach 6 Phase II Approach 9 Chapter 3 Findings and Applications 9 Findings of Literature Review 11 Findings of Survey of State and Municipal Departments of Transportation 13 Discussion of Findings of Literature Review and Survey 14 Summary of Proposed Test Methods 22 Guidance on Interpretation of Test Results 25 Application of Test Protocol 26 Chapter 4 Conclusions and Recommendations 26 Conclusions 26 Recommendations for Future Research 28 References 29 Attachment Recommended Methods of Test for Evaluating Durability of Detectable Warning Systems 105 Appendix Research Leading to the Development of Methodology for Durability Assessment of Detectable Warning Systems Note: Many of the photographs, figures, and tables in this report have been converted from color to grayscale for printing. The electronic version of the report (posted on the web at www.trb.org) retains the color versions.