Sonoma County, California Bridges: Napa Slough Bridge during the South Napa Earthquake

September 2014 (38.1599 Degrees, -122.3802 Degrees) Napa Slough Bridge

Most bridges performed well during last month's South Napa Earthquake. One exception was the Napa Slough Bridge. This bridge is supported on battered pile extensions that were damaged during the earthquake. Caltrans has long been concerned about battered piles since they resist lateral load axially rather than in flexure. Also, these piles are in poorly consolidated soft sediments that can move like a bowl of Jello when shaken. In contrast to the poor performance of the Napa Slough Bridge was the nearby Sonoma Creek Bridge that we studied in my blog of August 11, 2014. That bridge had similar battered pile extensions and similar poor soil, but the bridge had been retrofitted with big CISS piles and there was no damage during the earthquake.

Sonoma County, California Bridges: Napa Slough Bridge during the South Napa Earthquake by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Sonoma County, California Bridges: State Route 1 Bridge across the Russian River

September 2014 (38.4333 Degrees, -123.1000 Degrees) SR 1 Bridge

Continuing west on State Route 116 we arrived at the Pacific Coast Highway (SR 1) and the last bridge across the Russian River.  We've been traveling forward in time and so today's structure is a prestressed concrete continuous box girder bridge that was built in 1984. It's a six span bridge on single column bents and it's 910 ft long. 

This bridge has a coastal aesthetic. It's extremely streamlined and with a partially open railing to enjoy the scenic views. 

Sonoma County, California Bridges: State Route 1 Bridge across the Russian River by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Sonoma County, California Bridges: State Route 116 Bridge across Austin Creek

September 2014 (38.46722 Degrees, -123.04944 Degrees) Austin Creek Bridge

Just downstream from yesterday's bridge is the State Route 116 Bridge (20 0012) across Austin Creek. We've traveled from the 1920s to the 1960s and from truss bridges to continuous concrete box girder bridges. Today's structure is a four span bridge on single column bents and it's 380 ft in length. The creek bed must widen as it approaches the Russian River because the Old Duncan's Road Bridge was only 265 ft long. It looks like the bridge's foundations have been scoured by the creek. Also, the creek is barely flowing due to the drought.

Sonoma County, California Bridges: State Route 116 Bridge across Austin Creek by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.