Sunday, April 30, 2017

San Luis Obispo County, California Bridges: Salinas and Estrella River Bridges

July 2016 (35.7532, -120.6893) Salinas and Estrella River Bridges
We studied several Salinas River Bridges in our survey of Monterey County. We drove past another Salinas River bridge just south of the border in San Luis Obispo County (on our way to the coast). The River Road Bridge (49C0444) across the Salinas River is an eight span prestressed box girder bridge on single column bents that was built in 2005. The bridge is composed of 145 ft long spans for an 1150 ft long bridge without any skew or curve.

The Salinas River is usually a narrow channel surrounded by a broad floodplain and so the River Road Bridge was designed to be long enough to span the floodplain. This bridge carries traffic from the east into the town of San Miguel just north of Paso Robles.
Continuing south we followed the Estrella River (a tributary of the Salinas River) until we reached two bridges that carry State Route 46 traffic just west of Paso Robles. These are prestressed, 6-span, box girder bridges that were built in 2012. Note that the Estrella River Bridges have stone decorations on the wing walls, the railing, and on the column flares.
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Sunday, April 23, 2017

Monterey County, California Bridges: Bridges Near the Town of Bradley

July 2016 (35.80806, -120.85556) Nacimiento Lake Drive Bridge
I wanted to acknowledge a few bridges that we missed in our survey of Monterey County. The Nacimiento Lake Drive Bridge (44C0009) over the San Antonio River is a single lane Pratt truss bridge (with a steel deck) that was built by the Jones and Laughlin Steel Company in 1921. Note the guides on the deck to keep vehicles from banging into the truss members. Photos of details and modifications to the truss provided by Craig Philpott are on the Bridgehunter Website.

State Highway 101 is carried over a county road on the Jolon Road Bridges (44 0009R/L) in Bradley. The parallel bridges have three span haunched T beam superstructures and were built in 1936.
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Sunday, April 16, 2017

Monterey County, California Bridges: Pfeiffer Canyon Bridge South of Big Sur

February 2017 (36.239, -121.775) Pfeiffer Canyon Bridge (44-0060)
Readers may recall my mentioning that Highway 1 is slowly sliding into the sea. I've shown several examples of roads that have been turned into bridges to step over these slides. However, in February a bridge (the Pfeiffer Canyon Bridge (44 0060) on Highway 1) began sliding downhill and this part of Highway 1 is now closed.
The Pfeiffer Canyon Bridge was a three span, reinforced concrete, continuous box girder bridge on single column bents.
The bridge was built in 1968 and it got a seismic retrofit in 1996. However, what was done to protect this bridge from earthquakes wasn't enough to prevent it from moving once the ground that supported it started to slide downhill.
The trouble and expense of keeping Highway 1 open is perfectly illustrated by this bridge damage. The heavy rains caused accelerated sliding of the fragile slopes. There are several locations of road closure due to slides on Highway 1 on both sides of this bridge.
The California Conservation Corp completed a trail for residents to get around the damaged bridge which was removed in March (see photo below).
A new 300 ft long, single span, steel girder bridge has already be selected as a replacement. The long span will allow the bridge to step over the slide. The girders are already being fabricated and the new bridge will be completed by the end of September. Photos and videos of the damage and the bridge demolition are available from Caltrans and also on YouTube.
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