South Fork Snoqualmie River Bridge is completed by November 1, 1914.

  • By Priscilla Long
  • Posted 12/26/2007
  • Essay 8440

By November 1, 1914, construction of the South Fork Snoqualmie River Bridge (also called Denny Creek Bridge or Denny Camp Bridge) is completed. The 90-foot steel-truss bridge is located in eastern King County a few miles east of North Bend. Owned by the Washington State Highway Board and built by O. H. Stratton of Spokane, the bridge forms part of the new Sunset Highway, called Highway 2. The bridge will be maintained by the state until 1929, at which time Sunset Highway (now Highway 10, later Interstate 90) will be realigned with a new section that includes the concrete T-beam Denny Creek Bridge. King County will take over the now-bypassed road and bridge. Around 1937 King County will turn over the road and bridge to the United States Forest Service.

The bridge is located within the Mt Baker-Snoqualmie National Forest, part of a road now called USFR 58.  The Forest Service also operates Denny Creek Campground in the vicinity. The road and bridge served a few private homes and was occasionally used by road crews working on the highway through Snoqualmie Pass.

In 2002, Northwest Archaeological Associates made a National Register of Historic Places assessment of the South Fork Snoqualmie River Bridge. The report described the bridge as valuable from a historical perspective as part of the original Sunset Highway. The steel truss bridge illustrates a bridge type common in the late nineteenth and early twentieth century, with a truss structure derived from earlier wood-truss bridge designs. It is a pony truss, that is, one in which the two trusses lack lateral bracing above the traffic. It can also be called a through truss because the traffic flows at the same level as the bottom chords. The South Fork Snoqualmie River Bridge has a Pratt Truss, a configuration developed and patented by Thomas and Caleb Pratt in 1844.

The bridge is  constructed of five panels riveted together. It is not known whether the panels were prefabricated and brought to the site or built at the site. The bridge abutments are supported by rubble masonry. The South Fork Snoqualmie River Bridge is one of the very few bridges with a Pratt Truss of the pony type left in the state, and the only extant bridge with a Pratt truss in the National Forests of the state.

Sources: "National Register of Historic Places Assessment of the South Fork Snoqualmie River Bridge, Mount Baker-Snoqualmie National Forest," pdf document dated April 19, 2002, Northwest Archaeological Associates, Inc., Seattle, Washington.

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