Hamma Hamma River bridges

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The Hamma Hamma River Bridges are two three inch reinforced concrete through ribbed arch bridges that span the north and south forks of the Hamma Hamma River respectively. [1] [2] They were built as part of the Olympic Loop Highway, which is now U.S. Highway 101. [1] [2] Both bridges can be found on the National Register of Historic Places or National Register of Historic Places listings in Mason County, Washington. [3] [4] Each bridge is 154 feet long, and they both have 150 foot three hinged arch with a rise of 30 feet. [5]

Contents

North and South Hamma Hamma Bridges
North Bridge 5066.jpg
North Bridge
CarriesVehicular traffic
CrossesNorth and South Fork, Hamma Hamma River
Locale Eldon, Washington, U.S.
OwnerThe Washington State Department of Transportation
History
Engineering design byThe Washington State Department of Transportation
Fabrication byColonial Building Company of Spokane
BuiltNorth - 1923 South - 1924

History

Both bridges cross a marsh created by the Hamma Hamma River. Originally, U.S Highway 101 went around this marsh and crossed the river before it split off into two parts. [1] [2] [6]

In the early 1920s the Washington State Department of Transportation chose to cross the marsh, which shortened the alignment. [1] [2]

By spring of 1923, the engineers of these bridges finished designing it. In March of that year, State Highway Engineer, James Allen, signed off on the bridges. [1] [2] The State of Washington then applied for federal funding on March 24, which was provided by the Federal Aid Road Act of 1916. On the 8th of May, the project received formal United States Bureau of Public Roads approval. [1] [2]

The North Bridge finished being built in 1923 and the South in 1924. [1] [2] Since then, they've been modified twice. In 1970, the lowest overhead brace was removed to allow for more vehicle clearance and in the late 2000s, steel guard rails were added. [6]

Both bridges have some hints of deterioration such as leaching, spalls, nicks from vehicles, and an occasional exposed reinforcement bar. [1] [2]

South Bridge South Hamma Hamma River Bridge on US 101.jpg
South Bridge

See also

References

  1. 1 2 3 4 5 6 7 8 https://historicbridges.org/washington/us101hammahammariverbridgenorth/wa0451data.pdf Retrieved November 8, 2025.
  2. 1 2 3 4 5 6 7 8 https://historicbridges.org/washington/us101hammahammariverbridgesouth/wa0450data.pdf Retrieved November 8, 2025.
  3. ↑ "Bridges spanning north and south branches of the Hamma Hamma River op". www.historylink.org. Retrieved November 8, 2025.
  4. ↑ Record, Historic American Engineering. "North Hamma Hamma River Bridge, Spanning Hamma Hamma River Bridge at U.S. Route 101, Eldon, Mason County, WA". www.loc.gov. Retrieved November 8, 2025.
  5. ↑ "Revisiting Washington — Eldon" . Retrieved 2025-11-11.
  6. 1 2 "Hood Canal History: Bridging the Logo". Hama Hama Oyster Company. 2020-10-30. Retrieved November 8, 2025.
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