Revised May 2011
0623-2824P-MTDC
This document was produced in cooperation with the Recreational Trails
Program of the Federal Highway Administration, U.S. Department of
Transportation.
Notice
This document is disseminated under the sponsorship of the U.S.
Department of Transportation in the interest of information exchange. The
U. S. Government assumes no liability for the use of information contained
in this document.
The United States Government does not endorse products or
manufacturers. Trademarks or manufacturer’s names appear in this report
only because they are considered essential to the object of this document.
The contents of this report reflect the views of the authors, who are
responsible for the facts and accuracy of the data presented herein.
The contents do not necessarily reflect the official policy of the U.S.
Department of Transportation.
This report does not constitute a standard, specification, or regulation.
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
Revised May 2011
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
iii
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
iv
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
v
Contents
vi