A permanent replacement for the section of a Washington state freeway bridge that collapsed last week is expected in place by early autumn, and a temporary span could be up by mid-June, Washington state Governor Jay Inslee said on Sunday.
A 160-foot (48-meter) section of the Interstate 5 bridge over the Skagit River about 55 miles north of Seattle collapsed on Thursday after being struck by a truck carrying an oversize load. Two vehicles behind the truck plunged into the frigid waters below, and three people were plucked from the river with non-life-threatening injuries.
The remaining portion of the bridge has been inspected and will not need to be replaced, Inslee said in a statement.
"We will install a temporary span on the bridge that will restore traffic while we build a safe and durable permanent span adjacent to it," Inslee said.
The temporary span will accommodate fewer vehicles traveling slower than the normal limit of 60 miles per hour, the governor said.
Once the temporary span is in place, crews will begin working on the permanent replacement.
"The home stretch will be a two week total closure of I-5 likely in September as crews remove the temporary structure and move the permanent bridge into place," Washington State Department of Transportation Secretary Lynn Peterson said in a statement.
Inspection records show the bridge had been struck multiple times by vehicles over the past 10 years, National Transportation Safety Board Chairman Deborah Hersman said on Sunday.
Before Thursday, the most recent documented vehicle strike occurred in October, leaving visible gouge marks in the steel truss.
"This bridge has a history of over-height vehicle hits," Hersman said.
The flatbed truck that caused the collapse, operated by Mullen Trucking, of Alberta, Canada, was permitted by the Washington State Department of Transportation to carry a load with a height of 15 feet and 9 inches.
The truck driver told investigators he repeatedly measured the height of his load at 15 feet, 9 inches Hersman said. The truck was traveling southbound in the right lane when it struck the bridge, she said.
The bridge clearance was shorter on the sides than in the middle. Its lowest clearance point was 14 feet, 6 inches while the highest point was in the middle, measuring 18 feet, Hersman said.