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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2010. Criteria for Restoration of Longitudinal Barriers. Washington, DC: The National Academies Press. doi: 10.17226/14374.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2010. Criteria for Restoration of Longitudinal Barriers. Washington, DC: The National Academies Press. doi: 10.17226/14374.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2010. Criteria for Restoration of Longitudinal Barriers. Washington, DC: The National Academies Press. doi: 10.17226/14374.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2010. Criteria for Restoration of Longitudinal Barriers. Washington, DC: The National Academies Press. doi: 10.17226/14374.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2010. Criteria for Restoration of Longitudinal Barriers. Washington, DC: The National Academies Press. doi: 10.17226/14374.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2010. Criteria for Restoration of Longitudinal Barriers. Washington, DC: The National Academies Press. doi: 10.17226/14374.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2010. Criteria for Restoration of Longitudinal Barriers. Washington, DC: The National Academies Press. doi: 10.17226/14374.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2010. Criteria for Restoration of Longitudinal Barriers. Washington, DC: The National Academies Press. doi: 10.17226/14374.
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Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

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 656 Subscriber Categories Maintenance and Preservation Criteria for Restoration of Longitudinal Barriers Hampton C. Gabler Douglas J. Gabauer Carolyn E. Hampton VIRGINIA POLYTECHNIC INSTITUTE AND STATE UNIVERSITY Blacksburg, VA 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. The Board is uniquely suited for this purpose as it maintains an extensive committee structure from which authorities on any highway transportation subject may be drawn; it possesses avenues of communications and cooperation with federal, state and local governmental agencies, universities, and industry; its relationship to the National Research Council is an insurance of objectivity; it maintains a full-time research correlation staff of specialists in highway transportation matters to bring the findings of research directly to those who are in a position to use them. The program is developed on the basis of research needs identified by chief administrators of the highway and transportation departments and by committees of AASHTO. Each year, specific areas of research needs to be included in the program are proposed to the National Research Council and the Board by the American Association of State Highway and Transportation Officials. 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 656 Project 22-23 ISSN 0077-5614 ISBN 978-0-309-11837-8 Library of Congress Control Number 2010926946 © 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 656 Christopher W. Jenks, Director, Cooperative Research Programs Crawford F. Jencks, Deputy Director, Cooperative Research Programs Charles W. Niessner, Senior Program Officer Emily R. Greenwood, Senior Program Assistant Eileen P. Delaney, Director of Publications Maria Sabin Crawford, Assistant Editor NCHRP PROJECT 22-23 PANEL Field of Design—Area of Vehicle Barrier Systems John C. Durkos, Road Systems, Inc., Stow, OH (Chair) David L. Little, Iowa DOT, Mason City, IA Roger P. Bligh, Texas A&M University, College Station, TX Bernie L. Clocksin, South Dakota DOT, Pierre, SD Dan DeMaria, Pennoni Associates, King of Prussia, PA Edward J. Denehy, Transportation Maintenance Division, Albany, NY Dean A. Focke, Dublin, OH J. Michael McManus, California DOT, San Diego, CA Carl M. Ochoa, Vista Engineering Services, Inc., Plano, TX Michael P. Pillsbury, New Hampshire DOT, Concord, NH Harry W. Taylor, Jr., Taylor Consulting, Washington, DC Kenneth S. Opiela, FHWA Liaison Frank N. Lisle, TRB Liaison 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 provides guidance to assist maintenance personnel in identifying levels of damage and deterioration to longitudinal barriers that require repairs to restore operational performance. Using pendulum testing, full-scale crash testing, and finite element simula- tions, the research team developed a “Field Guide for Criteria for Restoration of Longitu- dinal Barriers.” The report will be of particular interest to maintenance personnel respon- sible for the maintenance and repair of damaged longitudinal barriers. Transportation agencies expend resources to ensure that all longitudinal barriers meet the safety performance guidelines to which they were constructed. Barrier systems are dam- aged by a wide variety of activities and factors, including minor crashes, snow plowing, mowing operations, and deterioration due to environmental conditions. Such damage may or may not be repaired by maintenance forces. For example, snowplows often bend W- beam guardrails and sometimes bend or break the posts. Even seemingly insignificant bar- rier damage or deterioration may compromise a barrier’s safety performance. With limited maintenance budgets, state highway agencies often have large backlogs of needed safety-feature repairs. These agencies cannot afford to repair damage that does not alter a barrier’s safety performance, but significant barrier damage must be repaired to pro- vide adequate protection for the motoring public. Unfortunately, in the absence of objec- tive criteria for determining when repair is not required, highway agencies may be held to the unachievable standard of maintaining all safety features in as-built condition to avoid tort liability. Therefore, there is a need for objective, quantitative criteria in the form of guidelines for assessing damage and deterioration and determining when a longitudinal barrier requires repair or can remain in service. Under NCHRP Project 22-23, “Criteria for Restoration of Longitudinal Barriers,” Vir- ginia Polytechnic Institute and State University reviewed the current criteria for repair of longitudinal barriers and evaluated the crash performance of barriers with minor damage using pendulum testing, full-scale crash testing, and finite element simulations. Based on these evaluations, recommended repair guidelines were developed. The guidelines are presented in a format designed for use in the field by highway main- tenance personnel. The guidelines include the damage mode, quantitative repair thresholds, the relative priority of making the repair, and a sketch of the damage mode. F O R E W O R D By Charles W. Niessner Staff Officer Transportation Research Board

C O N T E N T S ix Acknowledgments 1 Chapter 1 Introduction 1 1.1 Research Problem Statement 1 1.2 Objectives and Scope 2 1.3 Organization of Report 3 Chapter 2 Synthesis of Current Repair Criteria for Longitudinal Barriers with Crash Damage 3 2.1 Objective 3 2.2 Methodology 3 2.3 Results 10 2.4 Discussion 10 2.5 Conclusions 11 Chapter 3 Research Approach 11 3.1 Research Plan 13 3.2 Pendulum Testing Plan 16 3.3 Full-Scale Crash Test Plan 16 3.4 Finite Element Modeling Approach 20 3.5 Validation of the Finite Element Models 21 3.6 Extensions to Other Damage Modes and Barrier Types 23 Chapter 4 Evaluation of Vertical Tear Damage 23 4.1 Baseline Tests 24 4.2 Method of Introducing the Vertical Tear 25 4.3 Results 25 4.4 Recommendation 28 Chapter 5 Evaluation of Horizontal Tear Damage 28 5.1 Method of Introducing the Damage 28 5.2 Results 29 5.3 Recommendation 31 Chapter 6 Evaluation of Splice Damage 31 6.1 Results 31 6.2 Recommendation 33 Chapter 7 Evaluation of Twisted Blockout Damage 33 7.1 Results 33 7.2 Recommendation 35 Chapter 8 Evaluation of Missing Blockout Damage 35 8.1 Results 35 8.2 Recommendation

39 Chapter 9 Evaluation of Hole in Rail 39 9.1 Results 39 9.2 Recommendation 42 Chapter 10 Evaluation of Crash-Induced Rail and Post Deflection 42 10.1 Objective 42 10.2 Evaluation Through Crash Tests 45 10.3 Evaluation Through Finite Element Modeling 49 10.4 Discussion 51 10.5 Conclusions 52 10.6 Recommendation 54 Chapter 11 Evaluation of Missing or Broken Posts 54 11.1 Approach 54 11.2 Validation of Finite Element Model 55 11.3 Results 56 11.4 Discussion 59 11.5 Recommendation 61 Chapter 12 Evaluation of Post Separation from Rail 61 12.1 Approach 61 12.2 Results 61 12.3 Discussion 65 12.4 Recommendation 66 Chapter 13 Evaluation of Rail Flattening 66 13.1 Approach 66 13.2 Results 67 13.3 Discussion 73 13.4 Recommendation 75 Chapter 14 Generic End Terminal Guidance 75 14.1 Generic End Terminal Damage Modes 76 14.2 Recommendation 78 Chapter 15 Conclusions 78 15.1 Summary of Current Practices 78 15.2 Method of Evaluation of Guidelines 79 15.3 Recommended Criteria for Restoration of Longitudinal Barriers 83 15.4 Guideline Format for Maintenance Personnel 84 Chapter 16 A Field Guide for the Restoration of Longitudinal Barriers 90 References

ACKNOWLEDGMENTS This research project was sponsored by the National Academy of Sciences under the NCHRP Project 22-23, “Criteria for Restoration of Longitudinal Barriers.” The authors wish to acknowledge the guidance of Charles W. Niessner, Program Office for NCHRP Project 22-23. We owe a special debt to the mem- bers of the NCHRP Project 22-23 Panel who were active participants throughout the research effort. The Project Panel provided the research team with many of the barrier damage photographs in this report, gave invaluable feedback on our project findings, and helped us develop and fine-tune our strategy for making this a project which could be readily implemented by the highway maintenance community. We thank Ken Opiela and the FHWA for making the FOIL facility available for the pendulum testing at no cost to the project. We gratefully acknowledge Trinity Industries, Inc., and Gregory Industries, Inc., for contributing the guardrail materials for the pendulum and full-scale crash tests at no cost. We also wish to thank Dhafer Marzougui, Pradeep K. Mohan, Chris Story, Scott Mosser, and Eduardo Arispe, the contract staff of the National Crash Analysis Center (NCAC) from George Washington University, for their assistance in the setup and execution of the tests. We wish to thank David Little and the Iowa DOT for hosting a workshop in Mason City, IA, in May 2009 on the proposed guidelines. The workshop allowed the research team to obtain invaluable feedback from actual maintenance practitioners which we have used to fine-tune the guidelines for improved read- ability and practicality. We wish to acknowledge Virginia Tech graduate students Craig Thor, Greg Webster, and Kristofer Kusano for assisting with the pendulum experiments; Qian Wang, graduate student, for his contribution to the weak-post analysis; and Weijia Wu, post-doctoral fellow, for his development of the preliminary finite element models for this project. The majority of the finite element analysis in this project was conducted by Carolyn Hampton and reported in her M.S. thesis, “Limits of Permissible Damage in Strong-Post W-Beam Guardrail.” The authors wish to thank Roger Bligh for providing TTI crash test data and Karla Polivka-Lechtenberg for providing the test reports and data for the UNL long-span crash tests. We also gratefully acknowledge LSTC and Altair Engineering for providing the academic software licenses used to develop the models.

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TRB’s National Cooperative Highway Research Program (NCHRP) Report 656: Criteria for Restoration of Longitudinal Barriers explores the identification of levels of damage and deterioration to longitudinal barriers that require repairs to restore operational performance.

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