Continued: Was Ohio bridge scare a warning?

When the Interstate 90 bridge over Ohio's Grand River buckled and nearly collapsed 12 years ago, painters under the deck scrambled for stable ground and highway officials ordered a shutdown that lasted through five months of repairs.

Investigators determined what was then a unique cause for the failure: Undersized and corroded gusset plates that were too thin to withstand an unusual load of construction vehicles and heavy equipment parked on the bridge that day.

With those factors eerily similar to preliminary findings in the I-35W bridge collapse in Minneapolis, victims and others are now asking why Minnesota transportation officials didn't learn lessons from the near-disaster in Ohio.

It is unclear exactly what MnDOT officials knew about the Ohio incident, which was not widely publicized at the time. The issue will go public Tuesday in a report by lawyers investigating the I-35W bridge collapse for the state Legislature.

Robert Stein, a former University of Minnesota Law School dean, has said his Gray Plant Mooty law firm was looking at the Ohio incident to learn "what was done there, and what was learned here."

"Decisions were made, certainly in Ohio and perhaps in other states and in Minnesota, based on that knowledge, and we're trying to trace and track those decisions," Stein said last month.

Phil Sieff, a Minneapolis lawyer helping to represent victims of the I-35W bridge collapse, said the record will show that gusset plates on steel truss bridges required close inspection.

"We simply don't buy the notion that neither the state of Minnesota nor any other agency didn't know that gusset plates could cause a major failure," Sieff said.

Ohio incident led to changes

According to interviews and documents, the Ohio incident received federal review, was discussed in open forums and led to changes in Ohio. But the federal government's finding that "the design thickness of the gusset plate was marginal, at best" never resulted in the kind of nationwide technical alert that followed a similar finding last year in the investigation of the I-35W bridge collapse.

Dean Palmer, a principal at Richland Engineering in Ohio, helped investigate the I-90 bridge buckling and later presented findings at a conference. He also co-authored a 1997 trade journal article in Civil Engineering titled, "Grand Gusset Failure."

He said the crucial gusset plates on the fracture-critical Ohio bridge buckled downward and laterally by several inches because of three primary factors: Corrosion of the gusset plates, trucks and equipment parked atop the bridge as part of a painting project, and evidence that the 7/16th-inch-wide gusset plates were too thin when originally designed.

Richland Engineering estimated that at the time of the failure, the load on the bridge was approximately equal to or slightly greater than the full load capacity of the structure. The load included a line of parked construction trucks and heavy abrasive blasting, painting and lead-abatement equipment.

By comparison, the I-35W bridge was loaded with 287 tons of construction vehicles, sand and gravel for a repaving project when it collapsed last Aug. 1, killing 13 people and injuring 145. The highway administration later warned states not to overload bridges during construction jobs and to check the strength of gusset plates on steel truss bridges.

The National Transportation Safety Board has said the 1/2-inch-thick gusset plates on the I-35W bridge were too thin due to a design error.

Back then, it was an anomaly

But back in the late 1990s, Palmer said, the prevalent feeling among experts was that the I-90 bridge buckling was an anomaly. Federal officials, particularly those at the highway administration, seemed to be more interested in how long the bridge would be out of service and what would be done to fix it, he said.

"It shut down the interstate," said Palmer. "That was the big deal."

He said determining the cause of the buckling was "kind of an afterthought," partly because the damage to the bridge was limited and there were no injuries.

'A loud, sudden noise'

The federal highway administration's written report said painters heard a "loud, sudden noise" when the Ohio bridge buckled. One of the failed gusset plates was seriously corroded as a result of a leaking downspout, the report said.

Ian Grossman, a spokesman for the federal highway administration, said his agency did not put out any formal advisory about its findings. But he said the information was "informally shared among bridge and state leaders throughout the highway community."

Scott Varner, a spokesman for the Ohio Department of Transportation, said the information became a regular part of training for bridge inspectors in the state. But he said he didn't know whether federal or state officials passed the information to other state transportation agencies.

Lucy Kender, a spokeswoman for the Minnesota Department of Transportation, declined to comment on what, if anything, MnDOT learned from the Ohio incident.

Tom Sorel, MnDOT's new commissioner, said he's a firm believer in learning lessons from engineering mistakes. But being new to MnDOT, he's not sure what, if any, details of the Ohio accident were assimilated by MnDOT.

Until April 28, Sorel headed the federal highway administration office in Minneapolis. He said he recalled the Ohio bridge incident. If MnDOT got the findings, he said, he's not sure what they did with them. "So that's something I need to take a look at, to have a better understanding of what the reaction was here."

Sorel said that after the I-35W bridge collapsed, the federal highway administration office in Minneapolis talked to MnDOT about the Ohio incident. He said he was not part of those discussions. Separately, investigators with the NTSB looked for relevance to the I-35W bridge collapse by interviewing engineers who investigated the Ohio case.

Extra construction equipment

In 1997, Palmer gave a presentation at the International Bridge Conference in Pittsburgh. Besides commenting on the original thinness of the damaged gusset plates and related corrosion, he talked about the construction loading. "The gusset plates failed because the applied loads of the contractor's equipment and a legal truck load (traveling across the bridge when it buckled) exceeded the actual capacity of the gusset plates," Palmer said in a paper handed out at his presentation.

According to the list of attendees at the bridge conference, MnDOT sent a single representative, Thomas Merritt of the Bridge Office. But Merritt said he didn't attend Palmer's presentation. "I was looking for some of the gosh, wow new construction things," he said.

Even if he had attended the presentation on the Ohio bridge problem, he said he's fairly certain he wouldn't have done anything with the information.

"I might have said, 'Well, somebody made a mistake,'" Merritt said recently. "That's probably as far as it would have gone."

Tony Kennedy • 612-673-4213 Mike Kaszuba • 612-673-4388