"The NTSB reported none of these facts," says LePatner. "It dismissed any connection between the bridge's collapse and MN/DOT's maintenance of the bridge, or its poor condition for sixteen years prior to its failure. The report said nothing about MN/DOT's decision-making process or whether MN/DOT had acted prudently in light of the engineering consultants' recommendations to protect the well-documented fragility of the bridge."
The NTSB report ignored the bridge's inspection reports. The NTSB's findings were subjected to criticism even before they were published in November 2008.
In January of that year, after NTSB Chairman Mark Rosenker made a preliminary announcement that an error in the design of the gusset plates was the critical factor in the collapse of the bridge, James Oberstar of Minnesota -- chairman of the House Committee on Transportation and Infrastructure, who had promptly introduced a bill to overhaul national bridge inspection procedures following the I-35W disaster -- angrily accused the NTSB of rushing to judgment. That same month, in the Minneapolis-St. Paul Star Tribune, Jim Carlson, a member of the Minnesota legislature's joint committee on the I-35W Bridge collapse wrote, "The collapse was not an act of God; it was an error of oversight. Something was missed."
The NTSB report was negatively influenced by politics. On August 14, 2007, the Minnesota legislature appointed a joint committee to investigate the bridge collapse, which hired the law firm Gray Plant Mooty to produce its own report. One possible factor in the Minnesota legislature's decision to launch its own investigation was the suspicion aroused by NTSB's announcement, only a week after the I-35W Bridge fell, that a possible design flaw in the bridge's gusset plates caused the collapse.
Months later, NTSB Chairman Rosenker appeared at a press conference. Although in his opening statement he was careful to state that, "We have not yet determined the probable cause of the accident," he went on to call sixteen under-designed gusset plates the "critical factor that began the process of this collapse." This statement earned him a sharp rebuke from Rep. Oberstar, who wrote in a letter to Rosenker that, "Such announcements undermine the process and create the potential for committing the Board to conclusions which will be difficult to change if subsequent investigation suggests other possible conclusions."
Rosenker retracted his statements, but found himself at loggerheads with Oberstar again after the NTSB announced, in late March, that it would not hold an interim public hearing on the I-35W Bridge collapse. The three NTSB members -- all Republicans -- who voted against holding an interim public hearing explained their decision by stating that NTSB staff feared that holding such a hearing would take time and resources away from their investigation.
Oberstar and the two Democratic members of the NTSB (who issued a dissent from the majority's decision) replied by arguing that performing a thorough and trustworthy investigation was more important than speed. It was no small matter that the head of MN/DOT was Governor Tim Pawlenty's lieutenant governor, Carol Molnau, who herself was not an engineer experienced in infrastructure management.
"The politics surrounding the NTSB investigation certainly provide much fodder for speculation as to the possible political motivation of the board's leadership and findings," says LePatner. "But it does not require a political orientation to observe that the NTSB report has significant flaws, including errors of apparent neglect or omission as well as of technical understanding."
The NTSB report wrongly placed blame on the engineers. According to the NTSB report, a forty-year-old engineering error was the main cause of the bridge's failure. "The reality is that there has been a mass exodus of engineers out of the public sector," says LePatner. "It is likely the lack of engineers, not the decades-old design of the bridge, that contributed to its collapse. The Gray Plant Mooty report, which was commissioned by the Minnesota legislature following the collapse, pointed to various organizational weaknesses within MN/DOT that compromised the safety of the bridge: a poor flow of information; bad use of expert advice; and an organizational structure that impeded the maintenance process.