Nevada County, California Bridges: Bridgeport Covered Bridge across the South Yuba River (2)

December 2012 (39.2927 Degrees, -121.1949 Degrees) Bridgeport Covered Bridge

A look inside the Bridgeport Covered Bridge. It's called a Burr Arch Truss (patented by Theodore Burr in 1817) because the 'X' members of the Howe truss keep the bridge rigid while the timber arch carries the vertical load. However, computer models suggest that it is actually the truss carrying the load while the arch maintains stability. Whatever the case, the arch/truss structure can carry a longer, heavier span than either the truss or the arch bridge could carry alone. The structural members are Douglas Fir (and steel rods) while the 27,000 shingles are made from Sugar Pine.

The bridge model in the nearby museum shows the truss supported on the top of the stone abutments while the arch springs from the bottom of the abutments.

Nevada County, California Bridges: Bridgeport Covered Bridge across the South Yuba River (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License.