WSDOT begins work to finish SR 520 Montlake Project

Just as the State Route 520 (SR 520) Montlake Project is about to wrap up, work is already underway on the final piece of the plan, getting across Portage Bay to Interstate 5 (I-5).

Six years of construction has already started on the SR 520 expansion from Montlake to I-5. Several neighbors have already hit me up, annoyed with all the noise from the pile-driving, but pile-driving is going to be a constant through 2030.

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The Washington Department of Transportation (WSDOT) is building two parallel bridges across Portage Bay. Pile-driving for the work platform for the northern of the two bridges started a few weeks ago.  The plan is to build the new northbound span first and then build the southbound span. WSDOT needs to install 700 piles during the entire project. There will be five pile-driving seasons, each between September and April through 2030.

Tree and vegetation removal is already underway. The contractor is working on the west side of Portage Bay right now. Work near the Montlake Playfield will begin in January.

Work on the new Roanoke Lid will begin in 2026.

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You can expect a bunch of day and nighttime closures, full closures and neighborhood closures over the next five-plus years of construction.

This project is still running more than 70% overestimates, with a price tag of $1.4 billion. The only contractor bid came in way high, but the state decided to move ahead anyway. The legislature is expected to ask WSDOT to trim the costs as construction moves forward, which could mean design changes or a reduction in scope.

Chris Sullivan covers transportation for KIRO Newsradio. Check out more of Chris’ Chokepoints.

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