Local Information

Replacement bridge construction begins on SR 508 near Onalaska

Monday, April 16, 2018 - 09:54

Tamara Greenwell, communications, 360-905-2056
Joanna Lowrey, project engineer, 360-442-1350 

Historic pony truss bridge to be relocated in Washington State  

ONALASKA – Over the last three years, travelers on State Route 508 have used a temporary Bailey bridge to cross the Newaukum River east of Onalaska in Lewis County. However, the use of the temporary single-lane bridge will be ending soon.

On Tuesday, April 24, the Washington State Department of Transportation and its contractor Oregon State Bridge Construction Inc. will begin work to replace the aging structure with a new two-lane concrete bridge.

“We’re excited that this project will not only build a new bridge that can safely carry the weight of modern day traffic,” said Project Engineer Joanna Lowrey, “but it will also maintain a link to Washington’s past, by preserving the steel pony trusses from the historic bridge.” 

The existing South Fork Newaukum River Bridge is at the end of its useful life. To keep traffic moving safely until a replacement work is complete, WSDOT first weight restricted the bridge by prohibiting heavy loads to reduce stress on the steel support structure. A routine inspection found additional deterioration and a temporary Bailey bridge was placed over the top of the aging bridge span three years ago.    

Preserving historic bridges  

  • Built in 1930, the 197-foot steel pony truss bridge served the community for nearly 90 years.
  • Following a nationwide search, WSDOT identified a new owner who is committed to preserving the historic nature of the structure. 
  • The new owner plans to keep the bridge in Washington State. 

Construction details 

  • During construction, travelers should plan for delays of up to 20 minutes. 
  • Traffic will continue to alternate through a single lane across the bridge. 
  • To minimize delays, travelers will continue using the current bridge, until the new concrete structure is open to traffic. 
  • More significant traffic delays are expected later this year, during girder installation and then when shift traffic to the new bridge.

Construction on this $8.5 million project is scheduled for completion in late 2018.

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