Oregon City Arch Bridge
This is an historic arch bridge that connects Oregon City and West Linn across the Willamette River. Designed by the famed Oregon engineer, Conde B. McCullough, and built in 1922, it serves as a vital transportation route for Highway 43. Though the 755-foot-long bridge appears to be a concrete structure, it is actually made of structural steel covered with shotcrete, cast-in-place concrete, and other coatings.
Over the years, leaking expansion joints caused deterioration of the steel elements, and general weathering of the concrete portions of the bridge left protective coatings in poor condition. This extensive structural rehabilitation project involved removing and replacing all deteriorated or damaged steel and concrete, as well as seismic retrofit measures to increase the historic bridge’s resiliency in the event of an earthquake.
- It is the only bridge in Oregon to be encased in gunite, originally meant to protect it from corrosion due to the sulfur dioxide emissions from paper mills south of the bridge.
- The need to re-coat the steel bridge required the team to solve the shotcrete mix design and application procedure challenges to provide effective adhesion and durability.
- The 1922 bridge included many elements, such as luminaires and railings, that no longer met current design and safety standards, so the design team developed new elements that met historic aesthetic requirements while also bringing it up to code.
- ODOT-certified OBEC inspectors used specialized “confined space” techniques to safely inspect the entire interior of the steel arch spans, including monitoring equipment for insufficient oxygen and lead hazards.