ST. PAUL, Minn. — The largest group of victims from the Interstate 35W bridge collapse two years ago filed lawsuits Thursday against two companies that worked on the structure, saying the rush-hour disaster in downtown Minneapolis was "entirely avoidable."

ST. PAUL, Minn. — The largest group of victims from the Interstate 35W bridge collapse two years ago filed lawsuits Thursday against two companies that worked on the structure, saying the rush-hour disaster in downtown Minneapolis was "entirely avoidable."

Lawyers for 93 survivors and families of victims filed 79 lawsuits in Hennepin County District Court against URS Corp., a consultant that analyzed the bridge, and Progressive Contractors Inc., the St. Michael, Minn., company whose crews were resurfacing the bridge when it fell into the Mississippi River.

The Aug. 1, 2007, collapse of one of the state's busiest bridges during the evening rush hour killed 13 people and injured 145.

The lawsuits allege that San Francisco-based URS was negligent for failing to identify problems with the bridge, including a locked roller bearing and too-thin gusset plates connecting bridge beams. The exhibits include a handwritten note with a URS logo that says, "Gusset Plate Buckling — If this occurs, it is not catastrophic"

URS spokesman Ron Low said the company does not comment on pending litigation.

Progressive Contractors is accused of negligence for placing construction equipment and materials weighing more than 500,000 ponds above vulnerable gusset plates.

An attorney for Progressive Contractors, Kyle Hart, said the company is not liable. Hart said Progressive Contractors' crews put less weight than was allowed on the bridge.

"Had it been properly designed, the weight would have had no effect on the bridge," he said. "We just are adamant that we have no liability for this."

The National Transportation Safety Board attributed the collapse to a 1960s design flaw in the gusset plates, which were half the thickness they should have been.

Experts hired by attorneys for a group of more than 100 survivors and families of victims dispute that. They say the failure of a horizontal beam initiated the collapse of the bridge, which fell into the Mississippi River.

Attorney Chris Messerly said the survivors and relatives of victims are seeking unspecified monetary damages, which could be in the tens of millions of dollars.

Lawsuits from 21 other survivors and relatives against URS and Progressive Contractors are already under way, alleging breach of contract and negligence. Messerly said it's unlikely the two sets of lawsuits would be combined because the basis of their claims are different.

None of the cases are expected to go to trial before late 2010.