Bridge Railing Design Requirements (2024)
Chapter: Front Matter
Bridge Railing Design Requirements
TRANSPORTATION RESEARCH BOARD 2024 EXECUTIVE COMMITTEE*
OFFICERS
CHAIR: Carol A. Lewis, Professor, Transportation Studies, Texas Southern University, Houston
VICE CHAIR: Leslie S. Richards, General Manager, Southeastern Pennsylvania Transportation Authority (SEPTA), Philadelphia
EXECUTIVE DIRECTOR: Victoria Sheehan, Transportation Research Board, Washington, DC
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Ashby Johnson, Executive Director, Capital Area Metropolitan Planning Organization (CAMPO), Austin, TX
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Hani S. Mahmassani, W.A. Patterson Distinguished Chair in Transportation; Director, Transportation Center, Northwestern University, Evanston, IL
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Steward T.A. Pickett, Distinguished Senior Scientist, Cary Institute of Ecosystem Studies, Millbrook, NY
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Marc Williams, Executive Director, Texas Department of Transportation, Austin
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Shailen Bhatt, Administrator, Federal Highway Administration, U.S. Department of Transportation, Washington, DC
Amit Bose, Administrator, Federal Railroad Administration, Washington, DC
Tristan Brown, Deputy Administrator, Pipeline and Hazardous Materials Safety Administration, U.S. Department of Transportation, Washington, DC
Steven Cliff, Executive Officer, California Air Resources Board, Sacramento
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LeRoy Gishi, Chief, Division of Transportation, Bureau of Indian Affairs, U.S. Department of the Interior, Germantown, MD
William H. Graham, Jr. (Major General, U.S. Army), Deputy Commanding General for Civil and Emergency Operations, U.S. Army Corps of Engineers, Washington, DC
Robert C. Hampshire, Deputy Assistant Secretary for Research and Technology, U.S. Department of Transportation, Washington, DC
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Niloo Parvashtiani, Engineer, Mobility Consultant Solutions, Iteris Inc., Fairfax, VA, and Chair, TRB Young Members Coordinating Council
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___________________
* Membership as of May 2024.
NATIONAL COOPERATIVE RESEARCH PROGRAM
NCHRP RESEARCH REPORT 1109
Bridge Railing Design Requirements
John M. Holt
Maria D. Lopez
Thomas P. Murphy
MODJESKI AND MASTERS, INC.
Mechanicsburg, PA
Joshua S. Steelman
Scott K. Rosenbaugh
Andrew E. Loken
Ronald K. Faller
UNIVERSITY OF NEBRASKA-LINCOLN
Lincoln, NE
Marcus Galvan
FORESIGHT PLANNING AND ENGINEERING SERVICES, LLC
Austin, TX
Mark Bloschock
VRX, INC.
Plano, TX
Subscriber Categories
Highways • Bridges and Other Structures • Safety and Human Factors
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, 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 transportation results in increasingly complex problems of wide interest to highway 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 initiated 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 Agreement 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 committee 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, universities, and industry; TRB’s relationship to the National Academies is an insurance of objectivity; and TRB maintains a full-time staff of specialists 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 identified 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 Directors 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.
NCHRP RESEARCH REPORT 1109
Project 22-41
ISSN 2572-3766 (Print)
ISSN 2572-3774 (Online)
ISBN 978-0-309-70994-1
Library of Congress Control Number 2024939957
© 2024 by the National Academy of Sciences. National Academies of Sciences, Engineering, and Medicine and the graphical logo are trademarks of the National Academy of Sciences. All rights reserved.
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NOTICE
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COOPERATIVE RESEARCH PROGRAMS
CRP STAFF FOR NCHRP RESEARCH REPORT 1109
Waseem Dekelbab, Deputy Director, Cooperative Research Programs, and Manager, 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
NCHRP PROJECT 22-41 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., Louisiana Department of Transportation and Development, Baton Rouge, LA
Monique Hite Head, University of Delaware, Newark, DE
Timothy J. Keller, Ohio Department of Transportation, Columbus, OH
Taya Retterer, Texas Department of Transportation, Austin, TX
Eduardo Arispe, FHWA Liaison
AUTHOR ACKNOWLEDGMENTS
This research report was prepared under NCHRP Project 22-41 by a research team led by Modjeski and Masters, Inc., with John Holt as the Principal Investigator, supported by Dr. Thomas Murphy, Akshay Randiwe, Avinash Shaw, and Dr. Maria Lopez. The team consisted of Dr. Joshua Steelman, Andrew Loken, Scott Rosenbaugh, and Dr. Ronald Faller of the University of Nebraska-Lincoln/Midwest Roadside Safety Facility; Mark Bloschock of VRX, Inc.; and Marcus Galvan of Foresight Planning and Engineering Services, LLC.
FOREWORD
By Ahmad Abu-Hawash
Staff Officer
Transportation Research Board
NCHRP Research Report 1109: Bridge Railing Design Requirements presents an update to bridge railing design requirements to ensure consistency with the state of knowledge. The update incorporates the guidelines from NCHRP Research Report 1024: Evaluation of Bridge Rail Systems to Confirm AASHTO MASH [Manual for Assessing Safety Hardware] Compliance and NCHRP Research Report 1078: MASH Railing Load Requirements for Bridge Deck Overhang. The research findings will be used by state departments of transportation structural engineers responsible for designing and evaluating bridge railing systems.
The language of “Section 13: Railing” in the AASHTO LRFD [Load and Resistance Factor Design] Bridge Design Specifications, published in 2007, has not had a major revision since LRFD specifications were adopted. Some of the text date back to the 1989 AASHTO Guide Specifications for Bridge Railings. Then, in 2009, MASH replaced the 1993 NCHRP Report 350: Recommended Procedures for the Safety Performance Evaluation of Highway Features. Finally, on January 7, 2016, AASHTO and FHWA signed a joint implementation agreement requiring all new permanent installation and full replacement of bridge rails on the national highway system in contracts let after December 31, 2019, to be compliant with MASH.
Therefore, there was an immediate need to update the bridge railing design requirements to incorporate MASH requirements and address outdated language and areas of ambiguity particularly related to loads, load distribution to bridge barriers and deck overhangs, railing geometry, and analysis methods for determining the demand and capacity of bridge barriers.
Under NCHRP Project 22-41, “Proposed Modification to AASHTO LRFD Bridge Design Specifications, Section 13—Railing,” Modjeski and Masters, Inc. was asked to (1) propose updates to bridge railing design requirements and (2) develop examples to demonstrate the application of the proposed updates. The research team suggested draft language for consideration by AASHTO in the next update of the LRFD Bridge Design Specifications and provided analysis and design examples to illustrate the proposed updates.
An appendix containing the analysis and design examples is available by searching for NCHRP Research Report 1109: Bridge Railing Design Requirements on the National Academies Press website (nap.nationalacademies.org).
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CONTENTS
Evolution of AASHTO Bridge Rail Specifications
Comparison of NCHRP Report 350 to MASH 2016 Criteria
Impact Force Estimation Methods
AASHTO LRFD BDS Design Parameters
Design and Analysis of Bridge Rail Systems
Design and Analysis of Bridge Deck Overhangs
Barrier Geometry Considerations
Chapter 3 Synthesis of Literature Review
Accounting for Deck Flexibility
Dynamic and Static Increase Factors
Static Equivalent Design Loads
Static Equivalent Design Loads
Concrete Bridge Rail Design Methods
Transmission of Impact Loads to Deck Structure
Effect of Deck Flexibility on Barrier Capacity
Required Deck Overhang Strength
