tain components were "beyond tolerable limits," and one of the bridge's piers had "tilted to the north," they reported.

By 2000, the inspectors wrote that "eventual replacement of the entire structure would be preferable" to redecking the bridge. They added: "If bridge replacement is significantly delayed, the bridge should be re-decked."

That recommendation was repeated in every report afterward, but it never happened.

Since the collapse, public attention has focused on consultant reports in 2006 and 2007 that expressed serious reservations about the bridge. But a Star Tribune review of older reports by state inspectors shows that their concerns had been growing since the mid-'90s.

Gov. Tim Pawlenty said on Tuesday that the earliest suggested date for replacement by Minnesota Department of Transportation (MnDOT) engineers had been 2020.

Pawlenty defended the decisions made about the bridge.

"At no point did anyone say the bridge needed to be closed, or that there was imminent danger of failure," he said. "If they had, then certainly the commissioner and the MnDOT team certainly would have closed the bridge."We have to rely on the experts," the governor added. "They expressed concerns about the bridge, but at no point, as far as I know, did anyone ever say 'close the bridge.' "

However, in every report since 2000, inspectors urged the state to replace bolts in a specific area of the bridge, a job listed each year under "Immediate Maintenance Recommendations."

And since 2004 the reports repeatedly cited fatigue cracking in two girders as another problem requiring immediate maintenance, possibly including measures to relieve stress.

The precise significance of the problems cited by the inspectors over the years is unclear. More than 11,000 comparable bridges in the nation have deficiency ratings similar to those of the I-35W bridge. Experts and bridge inspectors have offered divergent opinions about what should have been done with the bridge.

Spokesmen for the governor and MnDOT said that Commissioner Carol Molnau, who also is lieutenant governor, was not available Tuesday to answer questions about the earlier inspection reports. Agency officials would only respond to written questions regarding the significance of the annual reports and how transportation officials reacted to them.

"The fatigue cracks in the approach spans that occurred in the late 1990s were addressed by repairs and retrofitting of connections," MnDOT spokesman Kevin Gutknecht said in a written statement. He added that early replacement of the bridge was not considered in part because "no fatigue cracks had occurred in the main truss spans."

Taken as a whole, the inspection reports dating to the mid-1990s portray an aging bridge in need of mounting repairs.

IN 1996, REPORTS TOOK ON AN URGENT TONE

In many cases the reports simply lay out a long list of problems found rather than rating their severity, but in 1996 the inspectors began to take an urgent tone. Noting that a pier supporting steel spans had tilted to the north, the inspectors warned then, "As this will not be repaired in the near future, this area should be closely inspected!"

In 1998, inspectors wrote that "numerous fatigue cracks were found" in the approach spans on the north and south sides of the bridge, which was then three decades old. The report said the cracks were drilled out and the fractured beams reinforced with bolted plates.

In each subsequent annual report, inspectors repeated their reference to the fatigue cracks found in 1998.

The 1999 report said those cracks were among "areas of major concern," adding that "due to the widespread cracking these areas will now be inspected on six-month intervals."

Later reports recommended only annual inspections. Gutknecht said no further cracking was reported after November 2000, so the monitoring cycle was increased.

While the MnDOT inspectors were drawing attention to the cracking, the state sponsored a study by the University of Minnesota that offered some reassurances to public officials who were concerned about the expense of replacing the bridge.

The university's research concluded in 2001 that "fatigue cracking of the deck truss is not likely, which means that the bridge should not have any problems with fatigue cracking in the foreseeable future."As a result, MnDOT does not need to prematurely replace this bridge because of fatigue cracking, avoiding the high cost associated with such a large project."

Elwyn Tinklenberg, who was transportation commissioner at the time under Gov. Jesse Ventura, said that the university report is all he remembers of the I-35W bridge during his tenure.

'IT SOUNDED PRETTY CONFIDENT'

Tinklenberg said he was "comforted" by what he called "an outside review that represented the state of the art in the field. ... It sounded pretty confident. It was not hedging at all."

But MnDOT inspectors continued to express concern about fatigue cracking after the university report and the department asked the engineering design consultant URS to review the bridge's condition.

URS in 2006 expressed concerns that a serious fatigue crack might go undetected because of the difficulty in inspecting parts of the bridge that were difficult to reach. URS recommended steel plating as a fix.

But MnDOT engineers asked URS to come up with other options and the department ultimately chose an alternative that called for increased inspections and repairing any problems found. URS called that option the "most cost efficient," but warned that "the critical issue of this approach is to ensure" that inspectors don't miss any measurable flaws.

Chief bridge engineer Dan Dorgan said previously that MnDOT chose the inspection option because it worried that drilling to add plates might weaken the bridge.

"Things can change day to day," said Roberto Ballarini, a civil engineering professor at the University of Minnesota. "A crack could grow very little for a year. [It] could grow 10 times longer overnight. You see that in your windshield."

That potential problem was acknowledged by Dorgan last week.

"There are occasions when a crack grows very rapidly," he said.

Pat Doyle • 612-673-4504 • pdoyle@startribune.com Mike Kaszuba • 612-673-4388 • mkaszuba@startribune.com Laurie Blake • 612-673-1711 • lblake@startribune.com Dan Browning • 612-673-4493 • dbrowning@startribune.com

http://www.startribune.com/10204/story/1350090.html