42nd Ave Bridge Replacement Project

Project Overview

The 42nd Ave S Bridge is an important arterial for the City of Tukwila and surrounding communities. The bridge, built in 1949, is reaching the end of its design lifespan and needs to be replaced. The current 42nd Ave S Bridge consists of a 3-span 280-foot-long bridge with a sufficiency rating of 7.56 out of 100 and is considered both Structurally Deficient and Functionally Obsolete by the Federal Highway Authority (FHWA). The 2018 average daily traffic volume (ADT) was 10,300 vehicles per day with 30% of those vehicles being heavy truck traffic.

A consultant team has been brought onboard by the City to develop a design for a new bridge. A component of the design work will involve gathering feedback from community stakeholders to guide portions of the design process. There will be multiple opportunities for the public to share their thoughts on bridge design and other project features. The project is funded by federal and local sources.

To stay up to date on the project and learn about upcoming feedback opportunities, please sign up for the project mailing list below.


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Project Status Update

Crews are currently onsite conducting survey and geotechnical work. The measurements and research done by surveyors will inform engineers of existing site conditions and property boundaries. Crews will be working through the end of the year.

Crews will also be in the area clearing vegetation, so surveyors have access to locations where they need to take measurements. A drill rig will be used later this year to take soil samples of the land.



The project is currently in the design phase which will continue through 2021.


Contact Information

For immediate project questions, contact Cyndy Knighton at 206-431-2450 or email

For general project questions, please contact Adam Cox at 206-431-2446 or email