Napa County, California Bridges: State Route 29 across Sulphur Creek

December 2013 (38.50285, -122.46615 Degrees) Main Street Bridge

Today's structure is another Sulphur Creek Bridge (21 0016) but on Main Street (SR 29) in the town of St Helena. It's very similar to the previous bridge: a 60 ft long stone arch span built at the beginning of the last century, but this bridge was widened on the west side with precast girders in 1975.

The original bridge was built by A. Martini, designed by G.H. Wallace, and it's owned by Caltrans. During the last inspection the bridge scored good for the deck, superstructure, and substructure, it had a sufficiency rating of 60, and it carried over 18,000 vehicles a day.

This bridge is on a 35 degree skew. I wonder if it's even possible to build a skewed arch? More likely they put the bridge deck on a skew. Also, I wonder if the quarry can cut stones so that they span the whole width of the arch? You just order the stones 30 ft long and place them on the wooden form? However, if you built a skewed arch every stone would have to be a different length.

Napa County, California Bridges: State Route 29 across Sulphur Creek by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.