Sunday, April 24, 2016

Mendocino County, California Bridges: Albion River Bridge


October 2011 (39.2264, -123.7660) Albion River Bridge
You would think that public servants would be appreciated by the people they are trying to serve, but that is seldom the case. State bridge engineers have determined that the 71 year old Albion River Bridge needs to be replaced. It's in poor shape and it wasn't designed for large earthquakes. However, individuals pursuing their own interests have been trying to stop the replacement, even though their actions could result in casualties. A good article in the New York Times describes the main facts in the case.
 The Albion River Bridge is a 34 span simply supported timber truss bridge on timber tower bents. A single steel truss span on concrete towers crosses over the main channel. The bridge has a deteriorated timber deck, substandard wooded barrier rails, corroded steel members, and inadequate shoulders. Typically Caltrans would be getting complaints for allowing a functionally obsolete and structurally deficient bridge to remain on the highway. However, in this case Caltrans is being criticized for trying to remove a beautiful cultural artifact from the community.

Sunday, April 17, 2016

Sonoma County, California Bridges: NWP Haystack Landing Bridge across the Petaluma River (2)

April 2016 (38.2277, -122.6145) Petaluma River Bridge
Adjacent to the State Route 101 Bridge is a bascule bridge replacement for the Sonoma-Marin Area Rail Transit (SMART) and NWP Railroad.  The original Haystack Landing (Swing) Bridge across the Petaluma River (shown below) was built in 1903 by the Pennsylvania Steel Company and moved to Petaluma. The replacement, a railroad bridge across the Intercostal Waterway on Galveston Island, was sold to SMART as part of $70 million project to expand the railroad 40 miles between Santa Rosa to San Raphael.
The replacement bridge was built in Galveston in 1986 after the previous bridge was destroyed by a hurricane. In 2012 the 105 ft long bascule bridge was replaced with a much longer (300 ft long) lift bridge. The old bascule bridge was sold to SMART for $4 million. It was taken apart and carried by rail to California before being reassembled on Mare Island. The old swing bridge was sold for scrap and moved out of the way in September of 2015.
The replacement is a single leaf bascule with a Scherzer type of rolling lift span that has a quick and simple operation. The bridge can carry live loads without any mechanism and uses rack and pinion gears to raise and lower the span.
Creative Commons License
Sonoma County, California Bridges: NWP Haystack Landing Bridge across the Petaluma River (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Sunday, April 10, 2016

Sonoma County, California Bridges: State Route 101 Bridge across the Petaluma River (2)

April 2016 (38.2277, -122.6145) Petaluma River Bridge
I returned to Sonoma County to re-photograph a few bridges that had changed since I last visited in August 2014.

The State Route 101 Bridges across the Petaluma River confused me when I first saw them.  I eventually figured out that the two 1955 bridges on single column bents (shown below) were being replaced with a single T-girder bridge on three column bents (shown above).
The new bridge has a lot of architectural details (flared, ribbed columns, wavy lines representing the river on the bent caps, haunched girders, etc.). You can see the lost falsework (for pouring the deck) between the T girders in the photos above and below.
Creative Commons License
Sonoma County, California Bridges: State Route 101 Bridge across the Petaluma River (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Sunday, April 3, 2016

Marin County, California Bridges: San Rafael Viaduct

June 2010 (37.9686, -122.5208) San Rafael Viaduct
Just north of the S101-E580 Connector (on 101) is the San Rafael Viaduct (27-0035L/R/S), three long-span prestressed concrete box girder bridges that were built in 1965 and heavily retrofit in 1993.
The parallel bridges include column casings and link beams that can form plastic hinges and protect the columns during earthquakes.
This ends our study of the bridges in Marin County, a small but affluent region in California with an intense (and often gridlocked) network of transportation infrastructure along it's east coast and with very little infrastructure along it's rugged west coast.