Possible Minneapolis Bridge Flaw Found

The National Transportation Safety Board said it found issues with the collapsed Minnesota bridge's design, specifically its gusset plates — the steel plates that tie steel beams together — and said they would look into reports of wobbling.

The finding preceded a warning by the head of the U.S. transportation system, who cautioned that states consider the additional stress placed on bridges during construction projects.

"Given the questions being raised by the NTSB, it is vital that states remain mindful of the extra weight construction projects place on bridges," Transportation Secretary Mary Peters said Wednesday.

A construction crew was repairing the surface of the eight-lane Interstate 35W bridge over the Mississippi River when it collapsed on Aug. 1.

The NTSB said helicopter observations had found several "tensile fractures" in the superstructure on the north side of the bridge, but nothing that appeared to show where the collapse began. Investigators were verifying loads and stresses on the beams, as well as materials in the plates.

The specter of wobbling was raised by a worker who claimed to have noticed unusual swaying of the bridge in the days before its collapse. The company that was doing the work, Progressive Contractors Inc., rejected that report Wednesday. The company had said it didn't believe any of its work contributed to the bridge failure but hadn't responded directly to claims of wobbling.

"We have now met with every single worker who was on the bridge when it collapsed," Tom Sloan, vice president of the company's bridge division, said in a statement. "None of them observed or reported any unusual swaying."

Officials of the Minnesota Department of Transportation wouldn't comment to the Associated Press on the significance of the gussets in the bridge's collapse.

Gary Peterson, Minnesota's assistant bridge engineer, told The New York Times "I don't know what this could be," Mr. Peterson said. "I'm frankly surprised at this point. I can't even begin to speculate."

Meanwhile, Navy divers continued probing the wreckage of the collapsed bridge for bodies, and officials said they expected removal of heavy debris to begin later than expected to give the divers more time.

Five people are confirmed dead in the collapse, with at least eight others missing and presumed dead. At least eight people were still hospitalized Wednesday, one in critical condition.

Divers were carrying out "a very meticulous, hand-over-hand search of the scene," said their spokesman, Senior Chief Dave Nagle.

Navy and FBI dive teams are trying to go deeper into the debris of the bridge than the local dive teams that have been working since the collapse, police Capt. Mike Martin said. He expects it to be at least a week before cranes start regularly hauling out large pieces of debris.

Martin told reporters the recovery operation was a "very dangerous, very tenuous situation down there. The current is constantly changing," reported CBS News reporter Jim Krasula.

The FBI team had to abandon using the larger of its two unmanned submarines. The remote-controlled vehicle — equipped with a camera, sonar, lights and a grabbing arm — was too big to maneuver amid the unstable, twisted bridge wreckage and vehicles in the cloudy water, agent Paul McCabe said Wednesday.

Instead, FBI divers will try their smaller sub, a shoe-box-size vehicle equipped only with lights and a camera. It is more difficult for the sub to navigate the Mississippi River's stiff river currents because of the sub's smaller thrusters. The water where the divers are working ranges from 2 to 14 feet deep.

Debris removal had been expected to begin this week. The State Patrol said 88 vehicles have been located at the collapse site, including those in the Mississippi River.

Flags flew at half-staff at the Minnesota Capitol on Wednesday in honor of the victims, a week after the bridge collapse.

Thousands of people continued to flock to the site Wednesday. Police report a handful of arrests of people who have crossed security cordons around the bridge. But officials said most people are keeping a respectful distance.

Flying flags at half-staff at the Capitol in St. Paul followed observances Tuesday in which church bells tolled in downtown Minneapolis as residents observed a moment of silence for victims of the Interstate 35W bridge collapse.