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I-5 - Grand Mound to Maytown Stage Two - Replace Interchange

Project vicinity map. View entire map. Project area is at the I-5 interchange with US 12 (Grand Mound). 


Proposed interchange and realignment of I-5.


September 2014

  • This project is functionally complete but there are a few punch-list items to complete.
  • WSDOT awarded the contract to Tri-State Construction. Construction began January 2011.
  • Traffic over I-5 from US 12 or Old Highway 99 is on the new bridge across I-5.  
  • Three lanes of I-5  are open to traffic in each direction at 70 MPH. 
  • Six new cameras came online in December 2012 between Grand Mound and Maytown.

Why is WSDOT replacing this interchange?
Rebuilding the I-5/US 12 interchange at Grand Mound improves mobility and safety.

The End Result

The project modifies the interchange configuration. Both loop ramps are eliminated. Traffic signals are installed at both ramp intersections resulting in a typical "diamond" interchange configuration. On the east side of the interchange, the two existing exits from northbound I-5 are consolidated to one exit point.

The alignment of the US 12 roadway across the interchange is shifted to the north. This allows both bridges (over I-5 and the railroad) to be replaced with minimal impact to traffic.

Project Benefits

  • Safety. The project realigns and lengthens on- and and off-ramps at the interchange to provide the more room for vehicles to safely enter and exit the highway, adds signals and improves driver sight distance.

What is the project timeline?
The project is currently under construction and scheduled for completion October 2012.

Financial Information

Financial Data for PIN 300581B
Funding Source Amount ($ in thousands)
2003 Gas Tax (Nickel Funding) $26,965
2005 Gas Tax (TPA) $0
Pre-Existing Funds (PEF) $0
Total $26,965

Project signage will reflect the cost of construction engineering, project bid award and sales tax.

How can I get more information?
Steve Fuchs
Project Engineer
WSDOT Tumwater Project Office
821 Airport Court SE
Tumwater, WA 98501-6805
Phone: 360-570-6750

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