When Washington state Sen. Tracey Eide heard Thursday that a bridge had collapsed, she thought immediately of the Interstate 5 span over the Columbia River.

"I've been on that bridge and it shakes and it scares me," she said. "It's built on wood pilings and when you talk about an old bridge, that is it."

Eide, D-Federal Way, co-chairs the Senate Transportation Committee. She sees the failure of what turned out to be the Skagit I-5 bridge as a wake-up call for funding the proposed $3.4 billion Columbia River Crossing. Her committee is assembling a multi-billion-dollar package expected by Washington Gov. Jay Inslee to include the state's $450 million share of the CRC.

The Senate vote next month on that package is expected to be so tight -- a tie, at last count -- that the Skagit collapse could enhance the CRC's odds of survival. The prospect of vehicles plunging off the Columbia River's I-5 bridge is highly unlikely in the short term, but perhaps horrifying enough to jolt a Washington legislator or two into a vote in favor.

Yet CRC opponents remain adamant, perhaps no one more so than Sen. Curtis King, R-Yakima -- Eide's counterpart co-chairing the key transportation panel. He insists that, because of opposition to light rail's extension into Vancouver, the transport package won't make it out of committee if it includes CRC funds.

"That," Eide said, "would be a tragedy."

Great divide

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Partisans on either side of the CRC issue agreed on a few points Friday: It was a miracle no one died in the Skagit collapse, and

north of Seattle and

is urgent. Beyond that, the divide only deepened between those who see the CRC as a boondoggle and plot to extend light rail, and those who support the project to improve safety and cut congestion.

But politically, the edge Friday appeared to go to bridge proponents, who until now had emphasized the CRC's benefits more than potential disasters. Scenarios include geologists' predictions that the existing span will collapse or sustain major damage when a big subduction-zone earthquake hits the region.

Oregon Gov. John Kitzhaber raised the issue Friday after signing an agreement in Portland with U.S. Interior Secretary Sally Jewell to speed up infrastructure projects.

"Can you imagine what would have happened if the I-5 Bridge had collapsed at 5 o'clock on a Thursday night?" Kitzhaber asked. "We just need to get this moving. I hope my colleagues in Olympia will head there."

Opponents in Washington's Legislature resist any connection -- structural or political -- between the steel-truss Skagit and Portland-Vancouver bridges. They predict the CRC will die during the special session ending June 12.

Washington has until Sept. 30 to appropriate $450 million, matching Oregon's commitment, for the project to go forward. The CRC also depends on the U.S. Coast Guard issuing a bridge permit by that date, enabling officials to apply for $850 million in federal light-rail funds.

CRC managers say that missing these deadlines would bump the project from a federal funding queue, meaning it couldn't be revived for at least another decade.

Obsolete bridges

The existing Interstate 5 bridge connecting Portland and Vancouver is actually two bridges. The northbound span was built in 1917 and rehabilitated in 1958. The southbound bridge was built in 1958. Both got new decks in 1988.

Nine full-time Oregon state employees tend the bridges, performing regular maintenance.

The Federal Highway Administration rates both bridges functionally obsolete, meaning their design is outdated, such as having narrow shoulders and low vertical clearance. Neither bridge is rated structurally deficient, which means that a span needs work.

The Skagit bridge, built in 1955, was also listed as functionally obsolete. The bridge had a sufficiency rating of 47 out of 100 at its November 2012 inspection. The state average is 80, according to an Associated Press analysis.

The northbound Portland-Vancouver bridge's sufficiency rating is far lower -- 18.5, according to CRC managers. Its minimum vertical clearance is 15 feet, 3 inches, a foot higher than the Skagit bridge, where a truck hauling a tall load of drilling equipment hit overhead girders.

The southbound span over the Columbia River has a federal sufficiency rating of 51. Its minimum vertical clearance is 15 feet, 9 inches.

Both Portland-Vancouver bridges rest on wooden pilings that extend 60 to 70 feet into the liquefiable soils of the river bed, far short of Troutdale Formation rock at a depth of about 200 feet.

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More than 120,000 vehicles cross the river each day on the adjoining spans. About 11,000 of those were trucks, as of 2005, according to CRC officials.

CRC opponent Don Benton, a Republican state senator from Vancouver, said that an Oregon Transportation Department report concluded in 2005 that the existing bridge was good for another 60 years.

That's false, said Patrick Cooney, the transportation agency's communications director. He said the 60-year reference was one sentence in a report on an electrical upgrade. "No engineer gave an overall assessment of the bridge condition to be 60 years," Cooney said.

Benton expects the Skagit collapse won't change a single CRC vote. "This horrible incident is totally unrelated," Benton said. "The bridge sustained damage -- a truck hit it and broke it."

Judy Clibborn, D-Mercer Island, disagrees. She chairs Washington's House Transportation Committee.

Clibborn said, "It backs up what we're saying."

Staff Writer Scott Learn contributed to this report.