Work continues on 156th Street overpass

The 156th Street overcrossing’s four pier caps will provide a foundation for the bridge’s superstructure, whose girders could be laid as early as late May.  - Kirk Boxleitner
The 156th Street overcrossing’s four pier caps will provide a foundation for the bridge’s superstructure, whose girders could be laid as early as late May.
— image credit: Kirk Boxleitner

MARYSVILLE — Motorists on I-5 near north Marysville might have noticed the bridge pillars are already up and the westside ramp leading up to the 156th Street overcrossing is nearing completion, which means that the project as a whole has hit its halfway mark, but those drivers can expect some traffic slowdowns between now and the expected opening of the overcrossing in the fall of this year.

After general contractor Guy F. Atkinson Construction started work in August of last year, the bridge’s substructure work was wrapped up by the end of December, as eight drilled shafts — two at each of the bridge’s four piers, each one seven feet in diameter and roughly 120 feet deep — were drilled to form the foundation of the bridge, by being filled with concrete and steel.

“It’s an unusual depth,” said city of Marysville Construction Inspector Rick Herzog. “We have a very high water table, though. We’re only about 100 feet above sea level. That same wet ground is what made this area such a great place to grow strawberries.”

Before February came to a close this year, the aboveground portions of the bridge columns had been poured and formed, while work on the “fascia wall” that will wrap around the bridge columns on the eastside of I-5 began with the start of April.

“This wall, unlike the others, is primarily being installed for aesthetic purposes,” said city of Marysville Public Information Officer Doug Buell. “It’s not a retaining wall so much as it is an architectural wall, installed in part to discourage camping up under the bridge abutment.”

Construction of the remaining six structural support earth retaining walls will likewise continue from now through June.

“It’s basically panels and rebar mats holding everything in,” Herzog said.

Storm drains and water mains have been installed along the seventh retaining wall, as well as the connector roadway between 156th Street NE and Twin Lakes Avenue that’s been built up to sit approximately 10 feet above the surrounding fields.

“We’ve got about 700-800 feet of sewer line left to go,” Herzog said. “We’re moving the existing sewer out from under the embankment section of the bridge, for easier access.”

In addition to the two city employees on site, Herzog estimated that nine construction workers are involved in the “dirt work” of road-building and wall panel construction, while about five carpenters and five steelworkers are involved in setting up the rebar.

Within the next couple of weeks, not only should the luminaries, curbs and gutters be installed, as well as the paving laid, but the pier caps sitting atop and connecting each pair of columns should provide enough of a foundation for the bridge’s superstructure that girders can be set over I-5 later this month.

“Our planners are still reviewing this stage,” said Mike Gallop, development construction engineer for the Washington State Department of Transportation. “We’ve generally looked at this as a city project with general permits for state right-of-ways. The girders will go up at night, probably in the middle of the week, and there will be lane closures.”

Gallop complimented the city of Marysville as “very cooperative” in working with WSDOT and characterized the 156th Street overcrossing as a project that’s gone well so far.

This project’s $13 million cost is being funded by a public/private partnership through a Local Improvement District with local property owners, and is intended to relieve traffic congestion on 172nd Street at Smokey Point.

For further updates on this story, check the city of Marysville’s website at


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