Seven years before the Interstate 35W bridge fell, a consulting firm sent Minnesota officials a proposal to shore up the aging structure that included examining its gusset plates — the connections that federal investigators now believe likely played a role in the collapse.

The preliminary plan from HNTB Corp. of Kansas City, which was buried among hundreds of documents released at a recent legislative hearing, has gone largely unnoticed in the debate over the disaster. The company did its study at no cost in an attempt to gain a state contract for the bridge work but, in the end, wasn’t hired by the Minnesota Department of Transportation (MnDOT).

A series of follow-up memos in 2000 and 2001 featured drawings of how HNTB planned to strengthen areas immediately surrounding the gusset plates and included renderings of “supplemental plates” and a “new oversize gusset.” Other drawings called for adding supplemental supports in the vicinity of the gusset plates.

Although a top HNTB official said recently that it’s impossible to say whether the company would have found the critical gusset plate problems now under investigation, the proposal is a rare documented instance in which experts explicitly planned to examine gusset plates.

“You have to check connections,” Ray McCabe, HNTB’s national bridge and tunnel director, said in describing what the company intended. “When you say connections, you naturally are describing the connections of these [large steel] members, which connect to gusset plates,” he said. “You can’t separate the bolts and the gusset; they form the connection.”

McCabe said the study mirrored what MnDOT was also seeking — a plan to add redundancy to a bridge that could collapse if one critical part failed.

“If the redundant scheme required a new gusset plate, or [it was needed] to facilitate a connection, most likely that would have been” done, McCabe said of HNTB’s plan.

Piqued investigators’ interest

The plan did pique the interest of Gray Plant Mooty, the law firm hired by a joint legislative panel to investigate issues surrounding the Aug. 1 collapse.

In its report to a legislative committee last month, the law firm contrasted HNTB’s proposal with one from URS Inc., another national consulting firm that was eventually hired by MnDOT.

“Importantly … the scope of the work under the URS contract did not include the analysis of the gusset plates that had been proposed by HNTB,” Gray Plant Mooty said.

In addition, according to the law firm, HNTB last month confirmed that the company’s cost estimate in its follow-up proposal “includes an item for the analysis of the ‘connections,’” a term that includes the gusset plates, the firm said.

Documents released to the Legislature show that HNTB’s preliminary report sat for more than a year before MnDOT decided to formally award a contract to study the bridge.

When it did so in 2003, MnDOT chose URS, which only a short time before had hired Don Flemming, formerly the longtime state bridge engineer at MnDOT.

Flemming left MnDOT in December 2000, seven months after HNTB made its initial proposal. He told the law firm that he “wanted to retire at the top of my game.” A month later Flemming was hired by URS.

Flemming said that before MnDOT issued a request for proposals that led to URS’ hiring, he made calls to MnDOT officials and talked with them about the services that he and URS could provide.

A URS spokesman last week said the company would not comment on the HNTB study, Flemming or the company’s own study of the bridge.

MnDOT spokeswoman Lucy Kender likewise declined to comment on the matter, including what role, if any, Flemming’s hiring by URS played in that company being hired.

She said MnDOT was preparing a detailed response to the Gray Plant Mooty findings, which she said would be released soon.

Hard to gauge ‘level of concern’

Bruce Mooty, a lead attorney in the law firm’s investigation, said it is difficult to speculate whether state officials missed an opportunity by not hiring HNTB. He said he could not gauge HNTB’s “level of concern” regarding the gusset plates.

As it studied the bridge over four years, URS settled on a complicated steel replating plan for the bridge’s main members that was ultimately set aside by MnDOT. How much the company focused on gusset plates is unclear, and URS officials have generally declined comment since the collapse.

One URS memo, written in 2005, said simply: “Gusset plate buckling — if this occurs, it is not catastrophic.”

Ed Zhou, a URS official, told Gray Plant Mooty investigators that the statement was hypothetical and related to the company’s study of a similar bridge in Cleveland.

Zhou told the law firm that URS did discuss how to evaluate the strength of the connections on the 35W bridge, but added that “we determined that it’s not necessary for us to get into the level of details of reexamining the gusset plate if they were designed properly.”

Although the official investigation of the bridge collapse by the National Transportation Safety Board isn’t expected to be completed until later this year, the NTSB has tentatively concluded that undersized gusset plates ordered in the original design of the bridge likely played a role.

Gray Plant Mooty records show that some MnDOT officials wanted to go ahead with hiring HNTB in late 2001. Notes from a December 2001 meeting at MnDOT, for example, show state bridge officials concluded that since replacing the bridge would not occur until at least 2016 “[we] decided to proceed with study HNTB/Dexter proposed.”

MnDOT officials told the law firm that the delay between HNTB’s late 2001 report and the decision to formally hire a consultant in early 2003 came because the agency could not hire the company without seeking competitive bids and had lingering questions about whether HNTB’s plan would fix the bridge’s weaknesses.

Dan Dorgan, who succeeded Flemming as state bridge engineer, acknowledged that “it appears that we made a choice not to push it that quickly.” He said that MnDOT had competing priorities at the time, including building Minnesota’s first light-rail line.

“They were very busy years for us,” said Dorgan. “It was one of those things we intended to do, but it wasn’t in our list of things.”

Mike Kaszuba • 612-673-4388