Historic Bridgeport Covered Bridge

Penn Valley, CA

The longest single-span covered wooden bridge in the nation, the historic Bridgeport Covered Bridge was deemed unsafe to cross by the State of California in 2011 following a comprehensive timber survey. The bridge was originally constructed in 1862 and features a Howe Truss with an auxiliary Burr arch — a structural system originally patented in 1817. The Howe Truss design consisted of X-braced compression-only members coupled with wrought iron tension rods at panel points connected to laminated double-staggered plank chords. Due to the nature of historic rehabilitation work, advanced analytical modeling was required to study the performance of this system and determine viable rehabilitation measures that preserved the character of the original design. The project involved replacement of fracture-critical elements (including wrought iron tension elements), replacement of decayed wood sections, resetting of structural members into cast iron footings, and rehabilitation of existing abutments. All repairs were reviewed and approved by a California State Parks Historian for conformance to Department of Interior Historical Standards for Historical Preservation strategies.