U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
202-366-4000
Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
| REPORT |
| This report is an archived publication and may contain dated technical, contact, and link information |
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| Publication Number: FHWA-HRT-17-039 Date: January 2016 |
Publication Number: FHWA-HRT-17-039 Date: January 2016 |
The bridge collapse occurred on August 1, 2007. The recommendation was issued January 15, 2008, and it was closed on November 14, 2013. The correspondence below took place between the FHWA and the NTSB as Recommendation H-08-001 was being developed and discussed. This content is taken from the H-08-001 Safety Recommendation History.(5)
| Correspondents | Date | Message |
|---|---|---|
| From: FHWA To: NTSB |
4/30/2008 | Letter Mail Controlled 5/5/2008 10:08:10 AM MC# 2080230: - From James D. Ray, Acting Administrator: The FHWA agreed with the safety recommendation and immediately issued Technical Advisory (TA) T5140.29 (Load-Carrying Capacity Considerations of Gusset Plates in Non-Load-Path-Redundant Steel Truss Bridges), dated January 15, 2008. I am enclosing a copy of the TA. Soon after the issuance of the TA, the FHWA Acting Executive Director held a teleconference with our field offices to discuss background information concerning the TA and provide an opportunity for questions and answers. Since then, the FHWA Office of Bridge Technology, in collaboration with the American Association of State Highway and Transportation Officials (AASHTO), has been providing technical assistance and guidance to the FHWA field offices and bridge owners in load rating and evaluation of gusset plates of steel truss bridges. Several teleconferences have been held with FHWA field offices and the State departments of transportation to resolve issues and answer questions. In response to NTSB Safety Recommendation H-08-1 in the Interim Report dated January 15, 2008, FHWA has taken actions within our legal authority. The States are taking positive steps to implement recommendations in the FHWA TA. We will continue to work with AASHTO, our State transportation partners, and other government agencies to assure continued compliance with the recommendation. We will consider any additional recommendations from NTSB when the final report on the investigation is issued and assess the progress of the States to determine whether additional actions are needed. We appreciate the NTSB’s efforts to address this safety concern promptly. We believe the issuance of the TA fulfills the intent of Safety Recommendation H-08-1, and recommend that H-08-1 be classified as Closed-Acceptable Action. For additional information, please contact Director Myint Lwin of the Office of Bridge Technology by telephone at 202–366–4589 or e-mail at myint.lwin@dot.gov or Mr. Firas I. Ibrahim of the Office by telephone at 202–366–4598 or e-mail at firas.ibrahim@dot.gov |
| From: NTSB To: FHWA |
7/23/2008 | The Safety Board commends the FHWA for its prompt issuance of Technical Advisory (TA) T 5140.29, Load-Carrying Capacity Considerations of Gusset Plates in Non-Load-Path-Redundant Steel Truss Bridges, on January 15, 2008, to supplement the American Association of State Highway and Transportation Officials’ (AASHTO’s) procedures for load rating steel truss bridges with respect to gusset plate considerations. The Board notes that, since the TA was issued, the FHWA, in collaboration with AASHTO, has been providing technical assistance and guidance to FHWA field offices, bridge owners, and State departments of transportation in load rating and the evaluation of gusset plates of steel-truss bridges. We are pleased that the transportation community is working together to implement this recommendation. Although the FHWA’s TA is currently receiving much publicity, resulting in subsequent actions by the States and other transportation agencies, the Safety Board believes that the advisory information should be codified through rulemaking and/or through inclusion in the AASHTO procedures or another appropriate document to ensure that this type of catastrophic accident does not recur. Although this is the only bridge failure of this type of which the Board is aware, we cannot dismiss the possibility that other steel truss bridges having nonredundant load paths may also have similar undetected design errors. By revising FHWA regulations and/or AASHTO procedures to include the advisory information, the FHWA will assist bridge owners in locating information they need to ensure the accuracy of original design calculations for this type of bridge before any future major modifications or operational changes are accomplished. Because AASHTO procedures have the effective force of an FHWA rule, but can be accomplished more quickly, an AASHTO procedure would satisfy the intent of the recommendation in an acceptable alternate manner. Pending final action, Safety Recommendation H-08-1 is classified OPEN -- ACCEPTABLE RESPONSE. |
| From: NTSB To: FHWA |
11/21/2008 | On January 15, 2008, the Safety Board issued the following safety recommendation to the FHWA: H-08-1 For all non-load-path-redundant steel truss bridges within the National Bridge Inventory, require that bridge owners conduct load capacity calculations to verify that the stress levels in all structural elements, including gusset plates, remain within applicable requirements whenever planned modifications or operational changes may significantly increase stresses. Safety Recommendation H-08-1 is currently classified OPEN -- ACCEPTABLE RESPONSE. Also on January 15, 2008, the FHWA issued Technical Advisory T 5140.29, Load-carrying Capacity Considerations of Gusset Plates in Non-load-path-redundant Steel Truss Bridges, which referenced-08-1 and advised bridge owners to take certain actions to supplement the AASHTO Manual for Condition Evaluation of Bridges. For new or replaced non-load-path-redundant steel truss bridges, bridge owners strongly encouraged to check the capacity of gusset plates as part of the initial load ratings. For non-load-path-redundant steel truss strongly encouraged to check bridges, bridge the capacity of gusset plates when performing load ratings condition or dead load, before making permit or posting decisions, or when necessary to account for bridge alterations that would increase stress levels in the structure. Finally, bridge owners were advised to review previous load rating calculations to ensure that the capacities of gusset plates had been adequately considered. In May 2008, the FHWA and AASHTO proposed a joint study of gusset plates, with the intent, among other things, of further developing and refining the guidance for bridge engineers in the proper design and rating of gusset plates, and guidelines, specifications, of developing and examples for the load and resistance factor design and rating of gusset connections. The Safety Board finds both of these timely responses commendable and takes particular note of the efforts of both the FHWA and AASHTO in providing technical assistance and guidance to FHWA field offices, bridge owners, and State departments of transportation in the load rating and evaluation of gusset plates of steel truss bridges. But while acknowledging the short-term effectiveness of the FHWA technical advisory, the Safety Board is concerned about the long-term implementation of the second action item in the advisory: (2) Future recalculations of load capacity on existing non-load-path-redundant steel truss bridges. Bridge owners are strongly encouraged to check the capacity of gusset plates as part of the load rating calculations conducted to reflect changes in condition or dead load, to make permit or posting decisions, or to account for structural modifications or other alterations that result in significant changes in stress levels. In the view of the Safety Board, this guidance would go further in preventing another gusset-plate-related catastrophic bridge collapse if it were codified through rulemaking or through appropriate guidance documents. Because the National Bridge Inspection Standards incorporate by reference3 the AASHTO Manual for Condition Evaluation of Bridges, in 23 Code of Federal Regulations 650.313©, a provision in that manual would have, for State bridge authorities, the force of a regulation. However, though the Manual for Condition Evaluation of Bridges was current at the time of the bridge collapse, it has since been replaced by the recently adopted Manual for Bridge Evaluation. The Safety Board therefore believes that AASHTO should modify the guidance and procedures in its Manual for Bridge Evaluation to include evaluating the capacity of gusset plates as part of the load rating calculations performed for non-load-path-redundant steel truss bridges. The Safety Board further believes that, when the findings of the FHWA AASHTO joint study on gusset plates become available, AASHTO should update the Manual for Bridge Evaluation accordingly. |
| From: FHWA To: NTSB |
9/24/2009 | Letter Mail Controlled 10/9/2009 2:43:14 PM MC# 2090631 - From Victor M. Mendez, Administrator: In reference to your Recommendation H-08-1 of the investigation of the failure of the I–35W bridge over the Mississippi River in Minneapolis, Minnesota, we respectfully request that H-08-1 be classified as: "Closed-Acceptable" for the following reasons. We addressed this recommendation in the letter dated April 30, 2008, noting that we had issued Technical Advisory TA 5140.29 in January ("Load-Carrying Capacity Considerations of Gusset Planes in Non-Load-Redundant Steel Truss Bridges) and taken several followup steps to implement the advisory (see enclosure 1). In response, the NTSB classified Recommendation H-08-1 as "Open-Acceptable Response" pending final action (enclosure 2). Since then, FHWA has prepared and published Load Rating Guidance and Examples, for Bolted and Riveted Gusset Plates in Truss Bridges (February 2009, copy enclosed) using both the LRFR (load and resistance factor rating) and the LFR (load factor rating) method with illustrated examples. We also sponsored several national teleconferences to familiarize FHWA and State bridge engineers with the use of the FHWA guidance. In addition, FHWA organized a seminar in June 2009 on "Load Rating of Gusset Plates of Connections of Steel Truss Bridges" at the International Bridge Conference (IBC) held in Pittsburgh, Pennsylvania. The seminar drew the largest crowd of all the seminars held at IBC this year. During the seminar: FHWA discussed the new guidance.* The Pennsylvania Department of Transportation (PennDOT) described its use of the LFR method in load rating of gusset plates. The New York State Department of Transportation explained how it is using LRFR in the load rating of gusset plates, and shared some lessons learned from retrofitting or strengthening connections. A consultant showed how to use finite element analysis to load rate gusset plates.* A software developer demonstrated how his software could be used for load rating of gusset plates. The FHWA is holding a series of Webinars on the inspection and load rating of gusset plates using the FHWA guidance and the methods the States are using. On September 24, 2009, the Webinar will focus on the spreadsheet being used by PennDOT in load rating gusset plates. Further, FHWA is cooperating with the American Association of State Highway and Transportation Officials in a full-scale testing of gusset plates to gain a better understanding of the performance of gusset plates. The goal is to issue guidance and specifications in the design, construction, and evaluation of connections in steel truss bridges. With the above completed activities and the ongoing research, deployment, and education activities, we believe that Recommendation H-08-1 has been put into practice and research. For additional technical information, please contact Mr. Myint Lwin, Director of the Office of Bridge Technology, by telephone at 202–366–4589. If I can provide further information or assistance, please feel free to call me. |
| From: NTSB To: FHWA |
8/19/2010 | The NTSB is aware that the FHWA issued Technical Advisory 5140.29008 in January 2009, published Load Rating Guidance and Examples for Bolted and Riveted Gusset Plates in Truss Bridges in February 2009, organized a seminar on "Load Rating of Gusset Plates of Connections of Steel Truss Bridges" at the International Bridge Conference (IBC) held in Pittsburgh, Pennsylvania, in June 2009, and held a series of webinars on this issue. The NTSB is pleased that, in addition to these actions, the FHWA has been working with the American Association of State Highway and Transportation Officials (AASHTO) to conduct a full-scale testing of gusset plates to gain a better understanding of their performance and, by the end of 2010, will issue guidance and specifications in the design, construction, and evaluation of connections in steel truss bridges. In 2008, the NTSB advised the FHWA that, because issuance of the AASHTO procedures would have the force of the issuance of an FHWA rule, it would satisfy the intent of the recommendation in an acceptable alternate manner. Accordingly, pending publication of the AASHTO procedures, Safety Recommendation H-08-1 remains classified OPEN – ACCEPTABLE RESPONSE. |
| From: FHWA To: NTSB |
9/11/2013 | From Victor M. Mendez, Administrator: The Federal Highway Administration worked with the American Association of State Highway Transportation Officials (AASHTO) on this recommendation. In July 2013, voting members of the AASHTO Subcommittee on Bridges and Structures voted unanimously to adopt the following: (1) Ballot Item 25, Make revisions to Articles 6.2,.6.3, 6.5.4.2, 6.7.3, 6.13.6.1.5, 6.14.2.8 and 6.17 of the LRFD Bridge Design specifications to provide comprehensive and more unified design approach for gusset plate designs, and (2) Ballot Item 41, Make revisions to the Manual for Bridge Evaluation: Section 1, Article 1.6; Section 6, Articles C6A.4 & C6A.6; Part B, articles C6B.5.2.1 & C6B.5.3.1; and Appendix L6B to provide specifications for the load rating of gusset plates. Documentation describing these two ballot items is attached. The July 2013 changes to the LRFD Bridge Design specifications and the Manual for Bridge Evaluation direct bridge owners to conduct load capacity calculations to verify the stress levels in structural elements, including gusset plates. These revisions will be included in the next publications of interim specifications or new editions of the AASHTO specifications. Meanwhile, bridge owners may begin to use the AASHTO LRFD Bridge Design Specifications and the Manual of Bridge Evaluation to design and load rate gusset plates, bridge owners may begin to use the AASHTO LRFD Bridge Design Specifications and the Manual of Bridge Evaluation to design and load rate gusset plates. Given the above described actions, we respectfully request that recommendation H-08-01 be classified as "Closed- Acceptable Action." |
| From: NTSB To: FHWA |
11/14/2013 | We are pleased that the FHWA worked with the American Association of State Highway and Transportation Officials (AASHTO) to develop gusset plate load rating specifications and improve gusset plate design. We are further pleased that the AASHTO Subcommittee on Bridges and Structures approved revisions, currently available on the AASHTO website, that will be incorporated into the 2014 update of both the LRFD Bridge Design Specifications and the Manual for Bridge Evaluation. These actions have the force of an FHWA rule and satisfy the intent of this recommendation in an acceptable alternate manner. Accordingly, Safety Recommendation H-08-1 is classified CLOSED—ACCEPTABLE ALTERNATE ACTION. |
