Evaluation of Bridge Rail Systems to Confirm AASHTO MASH Compliance (2022)

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2022 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 RESEARCH REPORT 1024 Evaluation of Bridge Rail Systems to Conrm AASHTO MASH Compliance William Williams Nathan Schulz Akram Abu-Odeh Texas A&M Transportation Institute The Texas A&M University System College Station, TX Subscriber Categories Highways • Bridges and Other Structures • Safety and Human Factors Research sponsored by the American Association of State Highway and Transportation Ofcials in cooperation with the Federal Highway Administration

NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed, and implementable research is the most effective way to solve many problems facing state departments of transportation (DOTs) administrators and engineers. Often, highway problems are of local or regional interest and can best be studied by state DOTs individually or in cooperation with their state universities and others. However, the accelerating growth of highway transporta- tion results in increasingly complex problems of wide interest to high- way authorities. These problems are best studied through a coordinated program of cooperative research. Recognizing this need, the leadership of the American Association of State Highway and Transportation Officials (AASHTO) in 1962 ini- tiated an objective national highway research program using modern scientific techniques—the National Cooperative Highway Research Program (NCHRP). NCHRP is supported on a continuing basis by funds from participating member states of AASHTO and receives the full cooperation and support of the Federal Highway Administration (FHWA), United States Department of Transportation, under Agree- ment No. 693JJ31950003. The Transportation Research Board (TRB) of the National Academies of Sciences, Engineering, and Medicine was requested by AASHTO to administer the research program because of TRB’s recognized objectivity and understanding of modern research practices. TRB is uniquely suited for this purpose for many reasons: TRB maintains an extensive com- mittee structure from which authorities on any highway transportation subject may be drawn; TRB possesses avenues of communications and cooperation with federal, state, and local governmental agencies, univer- sities, and industry; TRB’s relationship to the National Academies is an insurance of objectivity; and TRB maintains a full-time staff of special- ists in highway transportation matters to bring the findings of research directly to those in a position to use them. The program is developed on the basis of research needs iden- tified by chief administrators and other staff of the highway and transportation departments, by committees of AASHTO, and by the FHWA. Topics of the highest merit are selected by the AASHTO Special Committee on Research and Innovation (R&I), and each year R&I’s recommendations are proposed to the AASHTO Board of Direc- tors and the National Academies. Research projects to address these topics are defined by NCHRP, and qualified research agencies are selected from submitted proposals. Administration and surveillance of research contracts are the responsibilities of the National Academies and TRB. The needs for highway research are many, and NCHRP can make significant contributions to solving 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 research 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 by going to https://www.mytrb.org/MyTRB/Store/default.aspx Printed in the United States of America NCHRP RESEARCH REPORT 1024 Project 22-35 ISSN 2572-3766 (Print) ISSN 2572-3774 (Online) ISBN 978-0-309-68764-5 Library of Congress Control Number 2022949456 © 2022 by the National Academy of Sciences. National Academies of Sciences, Engineering, and Medicine and the graphical logo are trade- marks of the 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, APTA, FAA, FHWA, FTA, GHSA, or NHTSA 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 research 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 National Academies of Sciences, Engineering, and Medicine. 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 Academies of Sciences, Engineering, and Medicine; the FHWA; or the program sponsors. The Transportation Research Board does not develop, issue, or publish standards or speci- fications. The Transportation Research Board manages applied research projects which provide the scientific foundation that may be used by Transportation Research Board sponsors, industry associations, or other organizations as the basis for revised practices, procedures, or specifications. The Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; and the sponsors of the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturers’ names or logos appear herein solely because they are considered essential to the object of the report.

e National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, non- governmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Marcia McNutt is president. e National Academy of Engineering was established in 1964 under the charter of the National Academy of Sciences to bring the practices of engineering to advising the nation. Members are elected by their peers for extraordinary contributions to engineering. Dr. John L. Anderson is president. e National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president. e three Academies work together as the National Academies of Sciences, Engineering, and Medicine to provide independent, objective analysis and advice to the nation and conduct other activities to solve complex problems and inform public policy decisions. e National Academies also encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine. Learn more about the National Academies of Sciences, Engineering, and Medicine at www.nationalacademies.org. e Transportation Research Board is one of seven major programs of the National Academies of Sciences, Engineering, and Medicine. e mission of the Transportation Research Board is to provide leadership in transportation improvements and innovation through trusted, timely, impartial, and evidence-based information exchange, research, and advice regarding all modes of transportation. e Board’s varied activities annually engage about 8,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. e program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individuals interested in the development of transportation. Learn more about the Transportation Research Board at www.TRB.org.

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 AUTHOR ACKNOWLEDGMENTS The research team would like to thank the TTI Proving Ground for their support in performing the two full-scale crash tests. The information obtained from these crash tests provided significant value to the project. The computer simulations were performed using the Texas A&M High Performance Research Com- puting resources. The ability to use the Terra and Grace supercomputers allowed the research team to evaluate many different bridge rail systems. CRP STAFF FOR NCHRP RESEARCH REPORT 1024 Christopher J. Hedges, Director, Cooperative Research Programs Waseem Dekelbab, Deputy Director, Cooperative Research Programs, and Manager, National Cooperative Highway Research Program Sid Mohan, Associate Program Manager, Implementation and Technology Transfer, National Cooperative Highway Research Program Ahmad Abu-Hawash, Senior Program Officer Sheila A. Moore, Program Associate Natalie Barnes, Director of Publications Heather DiAngelis, Associate Director of Publications Claire Aelion-Moss, Editor NCHRP PROJECT 22-35 PANEL Field of Design—Area of Vehicle Barrier Systems Alexander K. Bardow, Massachusetts Department of Transportation, Boston, MA (Chair) Arielle Ehrlich, Minnesota Department of Transportation, Oakdale, MN Paul Fossier, Jr., Baton Rouge, LA Monique Hite Head, University of Delaware, Newark, DE Timothy J. Keller, Ohio Department of Transportation, Columbus, OH Dhafer Marzougui, George Mason University, Fairfax, VA Taya Retterer, Texas Department of Transportation, Austin, TX William B. Wilson, Wyoming Department of Transportation, Cheyenne, WY Victoria Brinkly, FHWA Liaison Kelly K. Hardy, AASHTO Liaison Stephen F. Maher, TRB Liaison

NCHRP Research Report 1024 presents an evaluation of bridge rail systems to confirm their compliance with the AASHTO Manual for Assessing Safety Hardware (MASH). The report recommends important revisions for consideration by AASHTO in the next update of the LRFD Bridge Design Specifications. The research findings will be used by structural and safety engineers responsible for designing and evaluating bridge rail systems at state departments of transportation. MASH is the latest in a series of documents that provides guidelines on testing and evalu- ating roadside safety features. Initially published in 2009 and updated in 2016, it represents a comprehensive update to crash-test and evaluation procedures to reflect changes in the vehicle fleet, operating conditions, and roadside safety knowledge and technology. The AASHTO Technical Committee on Roadside Safety (TCRS) and the FHWA have adopted a new MASH implementation plan with compliance dates by hardware category for installing MASH-compliant hardware. After December 31, 2019, all new installations of bridge rails on the National Highway System (NHS) must have been successfully evaluated according to the 2016 edition of MASH. Similar to NCHRP Report 350, MASH defines six test levels for longitudinal barriers. With respect to the LRFD Bridge Design Specifications, each test level places an increasing level of demand on the structural capacity of a barrier system. There was a need to evaluate the most common nonproprietary bridge rail systems used across the country to determine the level of evaluation required to demonstrate MASH compliance. Under NCHRP Project 22-35, the Texas A&M Transportation Institute research team was asked to review the research and assumptions supporting the AASHTO LRFD Bridge Design Specifications and Roadside Design Guide for bridge rail geometric design for MASH. The evaluation used finite element computer simulations and full-scale crash testing to validate the results. The research team developed modified geometric curves using the MASH specifi- cations similar to what is currently shown in section 13 of the LRFD Bridge Design Specifica- tions for minimizing vehicle interaction with bridge rail posts. These new geometric curves can help designers design MASH-compliant bridge rail systems. Appendices A through H are available on the National Academies Press website (nap.nationalacademies.org) by searching for NCHRP Research Report 1024: Evaluation of Bridge Rail Systems to Confirm AASHTO MASH Compliance. F O R E W O R D By Ahmad Abu-Hawash Staff Officer Transportation Research Board

Note: Photographs, figures, and tables in this report may have been converted from color to grayscale for printing. The electronic version of the report (posted on the web at nap.nationalacademies.org) retains the color versions. 1 Summary 3 Chapter 1 Background and Objective 3 Introduction 3 Research Objective 4 General Discussions 6 NCHRP Project 20-07/Task 395 19 Chapter 2 Preliminary Evaluation of AASHTO Geometric Curves 19 Introduction 19 Intermediate Validation 35 Evaluation of AASHTO Post Setback and Snag Potential Relationships 64 Chapter 3 Full-Scale Crash Testing 64 Introduction 64 Test Requirements and Evaluation Criteria 64 Test Conditions 68 MASH-2016 Test 3-10 on Bridge Rail on Deck 72 MASH-2016 Test 3-10 on Bridge Rail on Curb 83 Summary and Conclusions 85 Chapter 4 Validation of the Small Car Vehicle Model 85 Development of Bridge Rail Models 85 1100C Vehicle Model Modifications 90 Validation of Deck-Mounted System 101 Validation of Curb-Mounted System 112 Summary 113 Chapter 5 Final Evaluation of AASHTO Geometric Curves 113 Computer Simulation Results 125 MASH Crash-Test Data 129 Evaluation of New Geometric Curves 132 Assessment of NCHRP Project 20-07 Marginal Bridge Rail Systems 134 Chapter 6 Summary 134 Conclusions 134 Recommendations 135 References 136 Appendices A–H C O N T E N T S