Sunday, May 29, 2016

Monterey County, California Bridges: Bixby Creek Bridge

March 1999 (36.37192, -121.90197) Bixby Creek Bridge
Continuing down Highway 1 we arrive at the iconic Bixby Creek Bridge. I last wrote about this bridge in my blog of February, 2009. In the photo above Caltrans and Lawrence Livermore Labs are installing sensors to obtain the modal frequencies of the bridge before it is retrofit.
All of the sensors were installed in the morning and in the afternoon a truck filled with electronic equipment recorded the modal frequencies using the ambient vibration of passing vehicles.

Creative Commons License
Monterey County, California Bridges: Bixby Creek Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Sunday, May 22, 2016

Monterey County, California Bridges: Big Creek Bridge

(36.07000-121.59833) Big Creek Bridge
Continuing along Highway 1 on the Pacific Coast we arrived at the Big Creek Bridge, a 600 ft long bridge with two 180 ft long arch spans. This bridge was designed in 1938 by Christian Gutleben who made a specialty of designing arch bridges in California.
Like most of the bridges along the coast, the Big Creek Bridge is a 24 ft wide bridge with two traffic lanes and no shoulders. And like most of these bridges along the coast, the concrete is in poor shape due to the marine environment.

Sunday, May 15, 2016

Monterey County, California Bridges: The New Dolan Creek Bridge

(36.106, -121.625) New Dolan Creek Bridge
In 1960 the old Dolan Creek Bridge was replaced with a precast girder bridge. This two lane bridge is 400 ft long and supported on single column hammerhead bents. The bridge got a seismic retrofit in 1986 that consisted of cable restrainers. In 1996 a second seismic retrofit provided triangular shear walls at Bent 2 and Bent 3. However, erosion of the slope and deterioration of the concrete suggest that this bridge may need to be replaced again before too long.

Sunday, May 8, 2016

Monterey County, California Bridges: The Old Dolan Creek Bridge

(36.106, -121.625) Old Dolan Creek Bridge
Not all the arch bridges built along Highway 1 in the 1930s were made of reinforced concrete. The Dolan Creek Bridge was a three-pinned arch designed with redwood timber members. The bridge was built by H.L. McCready and designed by T.K. May who took a model of the bridge to the 1939 World's Fair.
A photo of the bridge model (shown above) illustrates the shallow deck over the arch and the deep truss supporting the deck for the support spans. The arch span was 180 ft in length and over 150 ft tall. Note the well designed pin supports at the ends of the arch. This was one of the first timber bridges built by Caltrans that used metal ring connectors to transfer the load between the members (making the joints stronger than the members). The bridge sections were prefabricated in Monterey and then shipped to the site for assembly.

After about 30 years the bridge was the worse for wear and it was replaced by a concrete bridge in 1961. However, the bridge timbers are still being used in a Big Sur house that the architect Will Shaw had built in 1974.

Read more here:

Sunday, May 1, 2016

Monterey County, California Bridges: Rocky Creek Bridge

June 2013 (36.37960-121.90221) Rocky Creek Bridge
Along coastal Highway 1 in Monterey County are six open spandrel arch bridges that were built in the 1930s.  The Rocky Creek Bridge is typical of these bridges with T girder approach spans, two arch ribs for the main span, and a deck supported by spandrel columns. It was built in 1932 with a 240 ft long arch span.
This bridge is substandard in many ways. It's only 24 ft wide and the reinforcement is corroded. Moreover, the coast consists of bluffs and headlands and so the highway is often closed due to landslides and flooding during the winter.

The bridges weren't designed for earthquakes and so they were all retrofitted by Buckland and Taylor in the 1990s. The retrofit was to tie the superstructure to the abutments (to act as a strut) and to strengthen the spandrel columns with casings, all without changing the appearance of these historic bridges.