Nevada County, California Bridges: Banner Ridge Road Bridge across SR 49

October 1990 (39.2428 Degrees, -121.0310 Degrees) Banner Ridge Road Bridge

I previously wrote about State Route 49, the Golden Chain Highway that follows the steps of the first gold miners in California. Route 49 continues north from Placer County all the way through Nevada County. There are many interesting bridges that are either on or near SR 49 in Nevada County.

The Banner Ridge Road Bridge is a continuous four span reinforced concrete bridge that carries State Route 20 over State Route 49 between Grass Valley and Nevada City. I like this bridge because of the unique and interesting 'X' shaped two column bents that support the box girder superstructure.

Nevada County, California Bridges: Banner Ridge Road Bridge across SR 49 by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License.

Nevada County, California Bridges: Truckee River Bridge (2)

December 2012 (39.3331 Degrees, -120.1626 Degrees) Truckee River Bridge

After doing a little digging around, I found that the Truckee River Bridge was one of eight bridges that won the '2002 Award for Excellence' from the Portland Cement Association.

Jury Comments: This is a terrific example of how to accomplish a lot with very simple elements. Assemble just the right shapes, give them just the right proportions, and the effect is an extremely elegant bridge that fits its environment very well.

More information about the bridge and the award can be obtained by going to the PCA website.

I thought it was interesting that no individual was given credit for the bridge design. The engineer is Caltrans Office of Engineering Services and the architect is Caltrans Bridge Architecture and Aesthetics Branch.

Nevada County, California Bridges: Truckee River Bridge (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License.

Nevada County, California Bridges: Truckee River Bridge (1)

December 2012 (39.3331 Degrees, -120.1626 Degrees) Truckee River Bridge

The Truckee River Bridge is a pretty viaduct that was built in 2003. It looks like one continuous structure, but since it has seven spans and it's 1525.7 ft long, it probably has an in-span hinge.

Caltrans architects must have helped design the interesting transition between the single column bents and the box girder superstructure. The bridge carries State Route 267 over Glenshire Drive, the Union Pacific Railroad, and the Truckee River.

Part of what makes this bridge so great is the spectacular scenery. At an elevation of over 5000 ft the bridge is dwarfed by the mountains and pine forests that surround it. We'll take a closer look tomorrow.

Nevada County, California Bridges: Truckee River Bridge (1) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License.

Niigata, Japan's Bridges: Heisei O'Hashi across the Sabaishi River (5)

August 2007 (N37.3888° E138.5767°) Heisei O'Hashi

In the photo above we are standing on the point bar island of the meandering Sabaishi River looking southeast across the Heisei O'Hashi Bridge. The abutment is supported on piles and it's undamaged but the approach has settled due to liquefaction and lateral spreading. The expansion joint is between the abutment and the superstructure and so it remains undamaged.

This is the best possible behavior from a bridge engineer's point of view. However, the bridge remained inaccessible until a road crew could rebuild the approach. Whether it's possible to design and build a connection between the road and the bridge that can remain in service following earthquakes has not been determined. Caltrans builds 30 ft long seismic approach slabs that should support traffic even if the ground beneath them fails, but they haven't been tested by a large earthquake.

This island is made of un-compacted alluvial material that liquefied and the roadway had to be repaired before traffic could get to the bridge.

Niigata, Japan's Bridges: Heisei O'Hashi across the Sabaishi River (5) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Niigata, Japan's Bridges: Heisei O'Hashi across the Sabaishi River (4)

August 2007 (N37.3888° E138.5767°) Heisei O'Hashi

Another view of the Heisei O'Hashi Bridge across the Sabaishi River. The bridge was impassable after the Kashiwazaki Earthquake until road crews placed asphalt at the approaches. Considering how much the approach settled (see green rails on approach) I wonder if they used a mud pump to raise the roadway?

Niigata, Japan's Bridges: Heisei O'Hashi across the Sabaishi River (4) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Niigata, Japan's Bridges: Heisei O'Hashi across the Sabaishi River (3)

August 2007 (N37.3888° E138.5767°) Heisei O'Hashi

Another view of the Heisei O'Hashi across the Sabaishi River. A simple design: a long concrete box girder, deepest at the center support and tapering at the ends sitting in front of the abutment backwall.

Like the nearby Kaiun Bridge, the abutments support plinths with panels providing scenes from nature, in this case flying waterfowl.

Niigata, Japan's Bridges: Heisei O'Hashi across the Sabaishi River (3) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Niigata, Japan's Bridges: Heisei O'Hashi across the Sabaishi River (2)

August 2007 (N37.3888° E138.5767°) Heisei O'Hashi

Another photo of the Heisei OHashi, a continuous two span prestressed concrete box girder bridge over the Sabaishi River.

Niigata, Japan's Bridges: Heisei O'Hashi across the Sabaishi River (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.