The department has come under sharp criticism for its upkeep of the 40-year-old Interstate 35W bridge, even as an ongoing federal investigation has highlighted a design flaw and the weight of construction materials on the bridge, rather than maintenance, as critical factors in the collapse that killed 13 people.
"Financial considerations, we believe, did play a part in the decision-making" over repair of the bridge, said Robert Stein, who oversaw the report prepared for lawmakers by the law firm Gray Plant Mooty.
"Sometimes it's easier just to take the least expensive alternative or just commission another study," Stein said.
For example, instead of a $40,000 ground-penetrating radar survey of the bridge deck in 2006, engineers dragged a chain across the span to listen for unsound concrete. The radar test, an internal e-mail notes, "was not completed due to lack of funding."
That same year, officials from the state's bridge division examined rehabilitation and reconstruction options. In meeting minutes, they noted that a replacement bridge would cost $75 million or more, a project they concluded would be "cost prohibitive" and not in the cards for 20 years.
In 2004 and 2005, presentations assembled for top-level department meetings had the Interstate 35W bridge on a list of "budget buster" bridges, referring to the major spans that were due for costly renovations or replacements over the next 10 years.
The new bridge, expected to be completed by this fall, will cost at least $230 million.
Transportation Commissioner Tom Sorel, who took the job last month after previous leader Carol Molnau was ousted, said he was reviewing the report and couldn't comment in detail on many of its findings.
"Addressing the condition and safety needs of our bridge system has never been and never will be subject to question due to budgetary concern," Sorel said. "We rely on and invest in the expert opinions and recommendations of our bridge engineering professionals."
Republican Gov. Tim Pawlenty has asked Sorel to determine whether the report should lead to changes in organization of the transportation department. But Pawlenty spokesman Brian McClung said, "Until the cause of the collapse is determined, it is not possible to know whether anything in this report is relevant to the bridge collapse."
Much of the report was devoted to flaws in the way the state DOT carried out inspections, then reacted to what they found. The report noted a lag of as much as six months between an inspection and the writing of a report, raising concerns that "fading memories" might lead to a lack of useful detail.
The 35W bridge was rated in "serious to poor" condition for 17 consecutive years by the National Bridge Inventory Standards.
The report said state DOT guidelines called for the rust to be scraped off bridge trusses so the good steel could be measured precisely. But after 1993 precise measurements weren't included in yearly bridge reports. That meant that in 1998, transportation officials recalculating the bridge's weight capacity had to use the original design measurements rather than the amount of good steel that was really on the bridge, the report said.
Two DOT inspectors who wrote inspection reports said they had never even seen a written copy of the guidelines about measuring the remaining metal. And supervisors who should have made sure the reports were complete did not, the report said.
The National Transportation Safety Board's investigation of the collapse has found that some of the bridge gussets - the plates that helped connect its steel girders - were too thin because of a design error. The NTSB investigation also said that the weight of construction materials placed on the bridge during resurfacing also was a factor in the Aug. 1 collapse, which injured 145 people in addition to the 13 deaths.
The NTSB probe is expected to conclude later this year.
--- Associated Press writers Joshua Freed in Minneapolis and Gregg Aamot in St. Paul contributed to this report.
