I-5 - SR 510 Interchange - Reconstruct Interchange

Project news​

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Why is WSDOT reconstructing the I-5 and Marvin Road (SR 510) interchange in Lacey?

Crews have reconfigured the interchange to create a diverging diamond interchange. The rebuilt interchange is intended to help ease congestion and reduce the potential for crashes. The project is being constructed ahead of planned major development in Lacey north of I-5.

When construction is complete, a diverging diamond interchange improves traffic flow by allowing drivers to make a free left turn onto the highway without stopping at a traffic signal.

The project also includes a new frontage road and extended Marvin Road on-ramp to southbound I-5. The frontage road will provide access into and out of planned development in the area adjacent to southbound I-5. Access will remain closed until the City of Lacey builds the local connecting streets.

The End Result
This project will benefit all users of the I-5/Marvin Road interchange and all modes of transportation. In addition to helping drivers, pedestrians and cyclists will also see improvements. The improvements will also help accommodate economic development for the Hawks Prairie community. This project will expand on previous improvements that have been implemented by the City of Lacey and WSDOT.

Needs & benefits

A diverging diamond interchange is a proven way to move more people and reduce the potential for collisions by reducing conflict points.


  • Late 2015 – Finalize project scope and determine project delivery method.
  • 2016 – Acquire right-of-way and environmental permits.
  • Early 2016 – Begin preliminary design.
  • Early 2017 – Begin final design.
  • July 9, 2018 - Project advertised for competitive bidding
  • Sept. 6, 2018 - Project awarded to Scarsella Bros, Inc.
  • Oct. 2018 – Begin construction.
  • Aug. 2, 2020 - Marvin Road overpass opened as a diverging diamond interchange.
  • Late fall 2020 – Complete construction.


Financial Data for PIN 300502C
Funding Source Amount ($ in thousands)
2003 Gas Tax (Nickel Funding) $0
2005 Gas Tax (TPA) $0
Pre-Existing Funds (PEF) $268
CWA $45,605
Total $45,872


Brian Whitehouse 
Project Office 

Doug Adamson
Media Relations  

I-5 - SR 510 Interchange locational map