Tuesday, September 2, 2014

Sonoma County, California Bridges: Guerneville Bridge across the Russian River (2)

August 2014 (38.50096 Degrees, -122.99556 Degrees) Guerneville Bridge
Here's the view from the deck of the Guerneville Bridge. On the Historical Bridges Website they criticized the 'cyclone fencing,' which was erected when they converted the bridge to pedestrian use. I would imagine the lampposts were also put on the deck after the bridge was retired from 'active' service. You can appreciate how long these Parker truss spans are in this view looking down the bridge deck. The vertical clearance is 16 ft and so the truss must have about a 22 ft section depth, which provides a 180 ft length (with additional truss members at mid-span). The depth becomes higher and higher to increase the length until a truss span is no longer economical at about 600 ft.
Creative Commons License
Sonoma County, California Bridges: Guerneville Bridge across the Russian River (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Monday, September 1, 2014

Sonoma County, California Bridges: Guerneville Bridge across the Russian River (1)

August 2014 (38.50096 Degrees, -122.99556 Degrees) Guerneville Bridge
The Guerneville Bridge (20 0091) used to be the State Route 116 Bridge across the Russian River. It replaced an even older truss bridge in 1922 and it was replaced by a concrete box girder bridge in 1998. This bridge is still in good shape but it's only 17 ft wide and not appropriate for two way traffic.

The Guerneville Bridge is composed of concrete T-beam approach spans on pile extensions and three Parker truss main spans on pier walls. As we've discussed before, a Parker truss is a Pratt truss with a rounded upper chord and with more segments than on a Camelback truss. If you look closely at the above photo you can see the trusses are composed of 10 panels with 10 top chord segments. The trusses include 'X' bracing across the middle panels, some laced truss members, and also cross bracing at the end of each panel with 'X' bracing. The bridge is 980 ft long with 180 ft long truss spans.
Creative Commons License
Sonoma County, California Bridges: Guerneville Bridge across the Russian River (1) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.