MINNEAPOLIS (AP) Investigators have a “working theory” that a poorly designed gusset plate and excessive weight on the Interstate 35W bridge led to the bridge’s fatal collapse on Aug. 1, U.S. Transportation Secretary Mary Peters said

Peters’ remarks, made Nov. 1 during a formal address to the White House Transportation Legislative Leaders Summit in Washington, D.C., mirrored statements she made in August, a week after the Minneapolis bridge collapse.

The National Transportation Safety Board, which is investigating the collapse, has said it will be at least a year before a formal finding is available.

NTSB spokesman Peter Knudson acknowledged the board is looking at design issues and the gusset plates, which connected steel beams, as well as the weight of construction materials and equipment on the bridge, among other factors.

“We’re also looking at the maintenance and repair history. We’re looking at the de-icing fluids — any role they may have played. We basically haven’t ruled anything out yet,” Knudson said.

State Sen. Steve Murphy, DFL-Red Wing, who chairs the Minnesota Senate Transportation Committee, said Peters told the Washington gathering that he attended that “a finding of fault was not going to be lack of inspection or lack of maintenance” by state officials.

“I think it taints the findings,” he said.

A spokesman for Peters, Brian Turmail, said the NTSB “would want to look into whether lack of maintenance was a factor in the collapse of the bridge.”

But Turmail added that “the working theory at the NTSB is that it is not a lack of inspections, but a design flaw and weight.”

A design flaw would give administration critics less of an opening to hold current officials at the Minnesota Department of Transportation or Gov. Tim Pawlenty responsible for the collapse, which killed 13 people and injured more than 100.

Construction of a replacement bridge began Nov. 1.