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Muddy Fork Bridge

After extreme flood events washed out the riverbank and eastern approach of the Muddy Fork Bridge in 1964 and 2006, there was a clear need for a long-term solution at this challenging site. Mount Hood National Forest worked with OBEC to fast-track the design of a replacement bridge that could be constructed deep in the forest.

Hydraulic clearance was the critical issue for the design. The primary goals were to span the river to the limits of the 1964 flood event, increase vertical clearance under the bridge, and eliminate the pier in the channel. OBEC selected a 170-foot-long prefabricated weathering steel truss bridge, as it offered the most benefits in addressing the significant conveyance needs at this site. Additionally, off-site pre-fabrication allowed for a fast-track schedule by considerably reducing the construction time.

  • Truss structures support loads within their rigid triangle shapes above the deck, rather than below. This bridge type is ideal for long, clear spans with no in-water piers and higher decks – improving hydraulic clearance.
  • Over time, the weathering steel turns dark orange, as it develops a protective layer of rust that covers the bridge.