Thurston County News


​Questions and inquiries regarding News Release content should be directed to the Thurston County Public Information Officer:

Meghan Porter

Bryan Dominique

Tuesday, September 6, 2022
Construction Starts Soon at US 12 and Sargent Rd in Grand Mound
Dana Bowers, Public Works Communications Specialist, 360-867-2358 or email

A rendering of what the completed project will look like. 

A contractor is scheduled to start work this summer on a roundabout to create a new intersection at US 12 and Sargent Road SW in Grand Mound. Construction will continue into next year and is expected to finish by Fall 2023. 

Two-way traffic will be maintained on US 12 throughout construction. Drivers can expect delays due to reduced speed limits in construction zones. Work is planned to take place from 7 a.m. - 6 p.m. Monday through Friday. As work is weather dependent and other issues may arise, this schedule is subject to change. 

US 12 is a major east-west highway that runs through southwest Thurston County. Travelers use this route to connect to I-5 and Grays Harbor County to the west. US 12 connects to SR 510 east of I-5 which is another vital highway carrying traffic to and from communities including Tenino, Bucoda, Rainier. Grand Mound's businesses and residences use US 12 daily to connect to I-5 and surrounding areas.

Increased development around this urban growth area is expected in the coming years. The completion of this roundabout adds an additional north south crossing of US 12 improving traffic flow for current and planned developments. Additional route options improve emergency response. This single-lane roundabout is designed to expand to a four-lane highway on US 12 in the future. 

Roundabouts have been found to reduce the severity of accidents while keeping traffic moving. Studies show that roundabouts provide: 

  • A 37 percent reduction in overall collisions 
  • A 75 percent reduction in injury collisions 
  • A 90 percent reduction in fatality collisions 
  • A 40 percent reduction in pedestrian collisions 
Development in Grand Mound provide services like banks, restaurants, and retail outlets which benefit residents. Local developers and the Chehalis Tribe have contributed funds for the construction of this project. 

Project updates will be provided on the US 12 and Sargent Road project page online

County Commissioners:

Carolina Mejia
District 1

Gary Edwards
District 2

Tye Menser
District 3