Bridge Collapse

MINNEAPOLIS (AP) ― Experts hired by attorneys for victims of the Interstate 35W bridge collapse say the National Transportation Safety Board got the cause of the disaster wrong, their lead attorney said Wednesday.

Attorney Chris Messerly said experts from the engineering firm Thornton Tomasetti Inc. told survivors and families of victims Tuesday night the "initiating event" wasn't the fracture of a key gusset plate in the bridge, but the failure of a horizontal beam called a chord.

Messerly leads a group of attorneys representing 117 families of victims and survivors for free. The engineers' conclusions give them legal grounds for suing two contractors that worked on the bridge before it collapsed Aug. 1. 2007, killing 13 people and injuring 145.

The experts concluded the "L9-L11 west" chord buckled because of heat stress on the bridge that day, the weight of construction materials on it, and frozen roller bearings that prevented the bridge from expanding as it should have to handle the heat. The engineers said the chord failure then caused the "U10 west" gusset to fail, Messerly said.

"This is the first time anyone has explained exactly why the bridge fell and why it fell at that time," Messerly said.

The NTSB concluded last November that the bridge collapsed because the gusset plate was half as thick as it should have been, due to a flaw in the original design from the 1960s.

That conclusion pointed to the bridge's designer, Sverdrup & Parcel, which can't be sued because the firm has dissolved and the statute of limitations on design errors has run out.

Messerly said they plan use the Thornton Tomasetti study when they file suit, probably in May, against URS Corp., an engineering consultant that analyzed the bridge before it fell, and Progressive Contractors Inc., which was resurfacing it.

They can't sue the state, which owned the bridge, because their clients gave up that right when they accepted compensation from a $36.4 million fund set up by the Legislature, though other victims have until April 16 to decide whether to take the state money.

Kyle Hart, an attorney for PCI, expressed skepticism about Thornton Tomasetti's conclusions.

"Obviously I'm interested in hearing anybody else's theories but I would tend to doubt the validity of that one," Hart said.

NTSB spokesman Terry Williams declined comment, as did URS.

Four other victims have already sued URS and PCI. PCI is seeking to add the state and Jacobs Engineering Group Inc., the successor company of the bridge's designer, as defendants in that lawsuit.

Messerly said they have photographic evidence that the state and URS knew the roller bearings where the bridge sat on its concrete supports were corroded and couldn't move. And he said PCI piled construction materials on the bridge that weighed as much as a Boeing 747, when it should have stored the materials for the resurfacing project elsewhere.

Hart said PCI doesn't accept all the NTSB's findings, but that the company contends its not at fault.

"It's not surprising that they're going to name everybody -- that's to be expected," Hart said. "But the key thing is nobody has demonstrated the amount of weight we had on the bridge was improper. ... If the bridge had not been improperly designed everybody says it would have held up that weight easily."

For now, Messerly said, the survivors and attorneys are calling for a nationwide inspection of roller bearings on all similarly designed bridges, and that any roller bearings found to be frozen should be fixed.

About 140 people packed a conference room to hear the engineers' presentation Tuesday night, he said. Some wept, while others were relieved to hear "the whole truth as revealed by these experts," he said.

"This painfully proved to everyone on the bridge that this was something that never should have happened, that it was easily preventable," he said.

-------

The original I-35W bridge over the Mississippi River opened in November 1967 and was 1,907 feet in length. The replacement bridge opened in September 2008 and measures 1,216 feet in length.

(© 2009 CBS Broadcasting Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)