Originally published May 26, 2013 at 9:21 PM | Page modified May 27, 2013 at 3:32 PM

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courtesy Washington State Department of Transportation

Computer-rendered visualization of the Skagit River bridge replacement span.

 Anatomy of the failed bridge

Mark Nowlin / The Seattle Times

 Emphasizing the importance of the Interstate 5 bridge over the Skagit River to the regions traffic flow and economy, state officials Sunday announced a plan to have a temporary fix for the collapsed span open by as soon as mid-June.

 A permanent fix could be done by September.

 The temporary fix will use steel girders and no trusses overhead. It will be placed where the section of the bridge collapsed and will consist of two 24-foot-wide structures with four lanes total (two in each direction).

 The four lanes will be narrower than what was previously there. The speed limit will be reduced and oversized vehicles will not be allowed on the temporary span.

 The temporary structures will be built off-site, then installed to minimize delays, state officials said.

Before the 160-foot section collapsed Thursday, about 71,000 vehicles a day used the bridge, which a National Transportation Safety Board official earlier Sunday said had a history of overheight vehicle hits.

 The section collapsed when an oversized truck struck one or more overhead crossbeams. Three people survived falls into the river with their vehicles.

 Gov. Jay Inslee said Sunday the plan for the temporary fix minimizes the closure time and keeps clear access to popular Skagit County retail business and destinations. If we can pull this off (by mid-June), thatll be great news.

 After the sections collapse, inspection crews gave the remaining span a good run-through, said state Department of Transportation spokesman Travis Phelps.

 Once the wreckage is removed, divers will be sent to determine the safety of the remaining bridge supports, but that cant occur until the NTSB finishes its investigation.

 As soon as the temporary fix is in place, work will begin on the permanent span. That work will take place just to the west of the temporary span.

 Crews will put temporary piers in the river to support a work platform.

 When that permanent section is completed, it will be rolled in and the temporary span removed.

 The permanent span will have lanes as wide as the current ones and will be able to handle oversized vehicles.

 The state has applied for federal money from an emergency fund to cover 100 percent of the cost of the temporary fix and 90 percent of the cost of the permanent span, said U.S. Sen. Maria Cantwell, D-Wash. The state would pay for the other 10 percent.

 Inslee's office has estimated the cost for temporary and permanent repairs at $15 million.

 The state has awarded the contract to remove the wreckage and build the temporary span to Atkinson Construction. It will put out a separate request for bids for the work on the permanent span, officials said.

 The permanent fix will have a life of 50 years, said Lynn Peterson, secretary of the Washington State Department of Transportation.

 But overall, the bridge including its older spans will still be considered functionally obsolete, a designation that means it cannot meet current traffic demands or does not meet current design standards.

 The bridge would be placed into a queue on a prioritized list of state bridges that need to be upgraded.

 The state of Washington does not lack for information about our bridges. We do not lack for designs for new bridges, Inslee said. We just lack the resources.

 One way or another, we have work to do to improve the states infrastructure, Inslee added.

 Earlier Sunday, NTSB Chairwoman Deborah Hersman said the I-5 Skagit bridge has a history of overheight vehicle hits.

 NTSB investigators came to that conclusion after looking over the past 10 years of inspection records for the bridge, Hersman said at a news conference Sunday morning in Burlington.

 The last documented hit was Oct. 22, 2012, and people can still see with the naked eye where the vehicle hit the bridge, she said. As you walk the bridge, you can see visible damage on other spans that are not so recent.

 The NTSB did not give a total figure for hits to the bridge from oversized vehicles, saying it was still looking over the past records.

 On Sunday, officials said they planned to interview witnesses and the driver of the pilot car that preceded the truck.

 The pilot car had a measuring pole attached, and the driver was supposed to alert the truck driver by radio if there were any height issues along the way.

 But that communication apparently didnt occur.

 Some witnesses apparently said they saw the pilot cars pole wagging as it was crossing the bridge. Hersman said her team was still putting together the complete picture of what happened.

 There are a lot of statements that will be put out there, she said. Some of those witness statements will be conflicting. Were going to work to corroborate all the interviews as well as look at videos shot from various vantage points.

 Whether the truck could have cleared the bridge if it had been in the left lane where the clearance was highest is very much the focus of our investigation, Hersman said.

 The truck is 15 feet 9 inches high. The height clearance at the center of the bridge is about 18 feet. The clearance at the fog line at the outside of the right lane is 15 feet 6 inches.

 The NTSBs preliminary report will be issued in 30 days.