James “Scott” Groenier
Project Leader
Merv Eriksson
Project Leader
Sharon Kosmalski
Project Assistant
USDA Forest Service
Technology and Development Program
Missoula, MT
7E72H69—FHWA Fiber-Reinforced Polymer
Trail Bridges
July 2006
This document was produced in cooperation with the Recreational Trails Program of the
Federal Highway Administration, U.S. Department of Transportation.
This document is disseminated under the sponsorship of the U.S. Department of
Transportation in the interest of information exchange. The United States Government
assumes no liability for its contents or use thereof.
The contents of this report reflect the views of the authors, who are responsible for the
accuracy of the data presented herein. The contents do not necessarily reflect the official
policy of the Department of Transportation.
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This report does not constitute a standard, specification, or regulation. The United States
Government does not endorse products or manufacturers. Trade or manufacturer’s names
appear herein only because they are considered essential to the object of this document.
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The Forest Service, United States Department of Agriculture (USDA), has developed this
information for the guidance of its employees, its contractors, and its cooperating Federal
and State agencies, and is not responsible for the interpretation or use of this information
by anyone except its own employees. The use of trade, firm, or corporation names in this
document is for the information and convenience of the reader, and does not constitute an
endorsement by the Department of any product or service to the exclusion of others that
may be suitable.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and
activities on the basis of race, color, national origin, age, disability, and where applicable,
sex, marital status, familial status, parental status, religion, sexual orientation, genetic
information, political beliefs, reprisal, or because all or part of an individual’s income
is derived from any public assistance program. (Not all prohibited bases apply to all
programs.) Persons with disabilities who require alternative means for communication of
program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET
Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to
USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C.
20250-9410, or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal
opportunity provider and employer.
i
Acknowledgments
For reviewing the manuscript:
Gary Jakovich, U.S. Department of Transportation Federal Highway Administration
Eric Johansen, E.T. Techtonics, Inc.
Cam Lockwood, Trails Unlimited
Kathie Snodgrass, Missoula Technology and Development Center
Brian Vachowski, Missoula Technology and Development Center
Jim Wacker, Forest Products Laboratory
Dan Witcher, Strongwell
For assistance with bridge inspections:
David E. Michael, Tahoe National Forest
Randall K. Nielsen, Wallowa-Whitman National Forest
Marcia J. Rose-Ritchie, Medicine Bow-Routt National Forests
Kathryn Van Hecke, Pacific Northwest Region
For photos used in this report:
Trails Unlimited, E.T. Techtonics, Inc., and Strongwell
ii
Contents
Introduction ___________________________________________________________ 1
Background on FRP Trail Bridges _________________________________________ 3
Composites at a Glance ______________________________________________________3
Pultrusion _________________________________________________________________4
Advantages of FRP Materials __________________________________________________4
Disadvantages of FRP Materials _______________________________________________5
Cost ______________________________________________________________________5
Planning, Ordering, and Installing FRP Trail Bridges _________________________ 6
Planning __________________________________________________________________6
Types of Composite Bridges __________________________________________________6
Delivery Methods ___________________________________________________________7
Ordering an FRP Bridge ______________________________________________________8
Transportation, Handling, and Storage _________________________________________9
Construction and Installation _________________________________________________9
Safety and Tools ___________________________________________________________ 15
Design of FRP Bridges _________________________________________________ 16
Design Specifications for FRP Pedestrian Bridges _______________________________16
Design Concerns __________________________________________________________16
Other Concerns ___________________________________________________________ 17
Inspecting and Maintaining FRP Bridges __________________________________ 18
Visual Testing _____________________________________________________________18
Tap Testing _______________________________________________________________18
Thermal Testing ___________________________________________________________18
Acoustic Testing ___________________________________________________________ 19
Ultrasonic Testing _________________________________________________________ 19
Radiography ______________________________________________________________ 19
Modal Analysis ____________________________________________________________ 19
Load Testing ______________________________________________________________ 19
Comparison of Inspection Methods ___________________________________________20
Qualifications for Inspectors _________________________________________________20
Visual Signs of Damage and Defects___________________________________________20
Side Trusses ___________________________________________________________20
Deflection ____________________________________________________________21
Connections __________________________________________________________21
Blistering _____________________________________________________________21
Voids and Delaminations ________________________________________________21
Discoloration __________________________________________________________22
Wrinkling _____________________________________________________________22
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Contents
Fiber Exposure ________________________________________________________22
Cracks _______________________________________________________________22
Scratches _____________________________________________________________23
Repair and Maintenance ____________________________________________________23
Bridges Tested at the Forest Products Laboratory __________________________ 24
Design Overview __________________________________________________________24
Materials _________________________________________________________________24
Simulated Design Live Load Testing ___________________________________________25
Analysis of Test Data _______________________________________________________26
Disassembly and Installation at Field Sites______________________________________27
Falls Creek Trail Bridge _________________________________________________27
Peavine Creek Trail Bridge ______________________________________________28
Reinspection ______________________________________________________________28
Case Studies and Failures ______________________________________________ 29
Transportation and Storage Problems _________________________________________29
Construction Problems _____________________________________________________29
Environmental Problems ____________________________________________________ 31
FRP Trail Bridge Failures ____________________________________________________32
Redwood National Park _________________________________________________32
Olympic National Park __________________________________________________33
Aquarium of the Americas _______________________________________________33
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Contents
Recommendations ____________________________________________________ 34
Selection Considerations ____________________________________________________34
Materials, Testing, Specifications, and Standardization ___________________________34
References ___________________________________________________________ 37
Appendix A—Glossary _________________________________________________ 37
Appendix B—Proposed Guide Specifications for the Design of
FRP Pedestrian Bridges _____________________________________________ 51
Appendix C—CSI Specifications for FRP Pedestrian Bridges_________________60
Appendix D—Test Data for Bridges at the Forest Products Laboratory _________65
Appendix E—FRP Trail Bridges in the United States ________________________ 70
Appendix F—Web Sites ________________________________________________ 76
Appendix G—FRP Suppliers, Designers, and Associations __________________ 75
Appendix H—Design of the Falls Creek Trail Bridge ________________________77
Appendix I—Example Installation Instructions _____________________________ 92
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Contents
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