NTSB chief backs statement on Minneapolis bridge flaw

The chairman of the National Transportation Safety Board is defending his decision to call an engineering flaw a “critical factor” in the collapse of the Minneapolis bridge that killed 13 persons and injured 145 others last summer.

The NTSB came under criticism last week from Rep. James L. Oberstar, Minnesota Democrat and chairman of the House Transportation and Infrastructure Committee.

Mr. Oberstar has said the NTSB’s Jan. 15 announcement that poorly designed steel plates played a role in the Interstate 35W collapse was “highly inappropriate” because the agency hasn’t concluded its investigation.

  • NTSB_REPORT.pdf”>NTSB report (PDF)

    But NTSB Chairman Mark V. Rosenker yesterday said investigators continue to “consider all evidence” in their probe of the collapse.

    “Although there is no reason to believe that any other bridge in the country has a design error of this magnitude, we do not want to proceed under such a hopeful assumption,” Mr. Rosenker said in a letter to Mr. Oberstar yesterday.

    Mr. Rosenker also met with Mr. Oberstar yesterday, in what a NTSB spokesman called a “cordial” exchange.

    Jim Berard, a spokesman for Mr. Oberstar, said the congressman was satisfied with Mr. Rosenker’s response.

    “He seemed to get the message [Mr. Oberstar] was trying to convey,” he said.

    Sixteen of the bridge’s 224 so-called gusset plates, which help connect steel beams supporting the bridge, were designed too thin, according to the NTSB. There are more than 400 steel-truss bridges similar to the I-35W collapse across the country, though Mr. Rosenker said he doesn’t think gusset plate design errors are a systemic problem.

    In his Jan. 23 letter to Mr. Rosenker, Mr. Oberstar said he was concerned that the announcement could undermine the NTSB’s investigation and “create the potential for committing the board to conclusions which will be difficult to change if the subsequent investigation suggests other possible conclusions.”

    Mr. Rosenker said it’s not uncommon for the NTSB to disclose safety concerns during an investigation.

    “Please be assured that it was not my intent to get ahead of the ongoing NTSB investigation or to hypothesize about the root and contributing causes of the bridge collapse,” he wrote.

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