Salmon Creek-area commuters are used to change by now. They’ve been introduced to a new park-and-ride lot, local street improvements and more spacious freeways in just the past two years.
Now comes the biggest change yet.
Construction crews are laying the foundations for a new bridge that will carry Northeast 139th Street up and over Interstate 5 and Interstate 205 — adding another east-west crossing to an often clogged interchange. Support structures are now taking shape as workers make progress on the 1,300-foot-long span.
The work is part of the Salmon Creek Interchange Project, a $133 million effort to remake the northern convergence of I-5 and I-205. The new 139th Street bridge is the last, largest stage of the four-phase project that aims to relieve congestion and improve safety in the area. Preliminary planning goes back as far as 1997, according to the Washington State Department of Transportation.
“It’s awesome,” WSDOT project manager Allen Hendy said of recent progress. “It’s definitely nice to see it finally come out of the ground. It’s been a long process to get here.”
Of the 54 shafts that will hold the bridge’s support columns, nine were complete as of Friday, Hendy said. Shafts go down as far as 130 feet into the ground, and are as wide as 9 feet in diameter. Inside goes a combination of steel, rebar and concrete designed to give bridge supports as much stability as possible, said WSDOT spokeswoman Heidi Sause. “That’s a huge portion of the bridge fixture that’s underground, so it’s anchored in bedrock,” she said.
To the west of I-5, several cylinder-shaped rebar cages — weighing about 100,000 pounds each — show the skeleton of those supports. By the time they’re all fortified with concrete, the supports will carry 139th Street over the freeways with the help of dozens of steel girders.
For now, crews under lead contractor Max J. Kuney Company don’t have to worry about avoiding traffic impacts. The bulk of
the work is happening well off the freeways, where no road exists yet. But that will change as the project makes its way over I-5 and I-205, Hendy said. It will also require periodic closures on both freeways (not simultaneously) when the time comes.
“We’re going to be dealing with it soon,” Hendy said.
Drivers to the east of the freeway will notice a change starting today. WSDOT will close a section of Northeast 17th Avenue for good, cutting off access to Northeast 139th Street at 20th Avenue. The closure will make way for the east end of the 139th Street bridge.
Drivers can still use other connecting streets between 17th and 20th Avenues. For affected businesses, particularly an Albertsons grocery store, crews are also rebuilding a parking lot to make more room for freight trucks delivering loads, Hendy said.
The 139th Street bridge could be mostly in place by the end of next year. Last week, Kuney Company superintendent Barry Gentle described it as “still in the very early stages.”
But once the bridge is open, drivers should see the benefits of the full project and its previous three phases, Sause said.
“This last piece is really the linchpin,” she said. “It really is the cornerstone of the project.”
The entire Salmon Creek Interchange Project is expected to be finished in 2014.