Plans are underway to construct a pair of temporary steel bridges over the Skagit River at Mount Vernon where a highway span collapsed into the water last Thursday.

The Everett Herald reported that the Associated Press had learned from an official who spoke on the condition of anonymity ahead of a formal announcement that the bridges will go up next to the original span and will allow limited travel over I-5.

Planners hope to have the temporary structures in place within three weeks. Repair work would then begin on the damaged bridge, with a goal of finishing that work by fall.

It is expected the federal government will cover 90 percent of the cost of the temporary bridge and the replacement.

A semi-truck carrying an oversize load clipped a steel truss, starting the collapse of the span and sending cars and people into the cold river waters, authorities said. The three people in the cars survived with non-life threatening injuries.

On Saturday, barges arrived at the river with equipment ready to remove the mangled steel, pavement and cars in the water.

The AP story quoted National Transportation Safety Board Chairwoman Debbie Hersman who said, on Sunday, that the bridge had withstood other over height collisions with vehicles in the past, with the most recent reported collision happening last October. She also said evidence of other collisions can be seen in the spans still standing over the water.