SR 99 - Cloverdale St & SR 509 - 112th St to Duwamish River - Paving & ADA

Project news

  • This project will be advertised for competitive bidding in January 2018.
  • Construction is scheduled to begin in spring 2018.
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Needs and Benefits

SR 99 between South Cloverdale Street and First Avenue South and SR 509 between South 112th Street and the Duwamish River are deteriorating, with ruts and cracks caused by years of heavy traffic. This project also will replace the ADA ramps between the sidewalk and the street at some locations, which will provide better sidewalk connections for people of all abilities. Repaving these sections of SR 99 and SR 509 will have several benefits:

  • Safety: This work will eliminate ruts and cracks where water can collect, which can reduce traction for vehicles.
  • Economic/Preservation: Repaving these areas of SR 99 and SR 509 will preserve the highways and their supporting layers, reducing the need for costly repairs.

What to expect

The paving work on SR 99 and SR 509 will require single lane closures and take place at night, when traffic volumes are lowest. On- and off-ramps also will close for a few nights for repaving; signed detours will be in place. About 32,000 vehicles use this section of SR 99 each day and up to 70,000 use this part of SR 509 daily.

Working in sections, crews will grind off about two inches of the existing asphalt surface and repave about two inches of new asphalt. Drivers should expect rough pavement and bumps in the areas that have been ground.

Work on the sidewalk/crosswalk transitions will take place during the day. Crews will use jackhammers, concrete saws and other equipment to remove the old sidewalk/crosswalk transitions, then install new transitions. People who use sidewalks may have to use detours during this work.

Project Timeline

  • January 2018: This project will be advertised for competitive bidding.
  • Late winter 2018: Project will be awarded.
  • Spring 2018: Construction will begin.
  • Fall 2018: Work will be completed.


The estimated total cost of this project is $6.9 million. The funding sources including pre-existing state funds and Connecting Washington.


Tom Pearce
WSDOT Communications
Phone: 206-440-4696