Los Angeles County, California Bridges: Slauson Avenue and Randolph Street Metro Bridges across the Los Angeles River

August 1999 (33.9797 Degrees, -118.1690 Degrees) Los Angeles River Bridges

Past the Atlantic Blvd. Bridge I turned around to photograph the Randolph Street Metro Railroad Bridge. It's a four span through girder structure. Looking back in the distance is the East Slauson Avenue Bridge (53C0445), a 5 span steel girder bridge built in 1942.

The railroad bridges are covered in graffiti, perhaps due to gang activity south of Los Angeles and also because the railroads may not have the resources to cover or remove graffiti.

Los Angeles County, California Bridges: Slauson Avenue and Randolph Street Metro Bridges across the Los Angeles River by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Los Angeles County, California Bridges: Winnetka Avenue Bridge across the Los Angeles River

August 2009 (34.1906 Degrees, -118.5710 Degrees) Los Angeles River Bridges

Continuing downstream along the Los Angeles River to the Winnetka Avenue Bridge (53C1388), a two span steel stringer bridge that was built in 1958. As can be seen in the photo, the nicest thing about these bridges is the barrier, the lampposts, and the surrounding vegetation. So far, the LA River is just a concrete channel with a deeper channel in its center.

Los Angeles County, California Bridges: Winnetka Avenue Bridge across the Los Angeles River by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Sonoma County, California Bridges: State Route 37 Bridge across the Petaluma River

August 2014 (38.11500 Degrees, -122.50500 Degrees) State Route 37 Bridge

Just north of the NWP Railroad Bridge is the State Route 37 Bridge (27 0013) across the Petaluma River. River crossings can be quite lively during earthquakes because they are so tall and flexible over the river. As the tall piers move back and forth the shorter piers can become overstressed and collapse. 

Note how today's bridge is composed of flexible two column piers with an occasional stiff four column pier to resist the large displacements. These stiff piers were retrofitted with steel casings on the longitudinal struts. Instead of retrofitting the columns to form plastic hinges the lateral members were designed to be ductile instead. The steel casings ensure that the struts can form reliable plastic hinges as the piers move back and forth.

Sonoma County: California Bridges: State Route 37 Bridge across the Petaluma River by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Calaveras County, California Bridges; Douglas Flat Bridge across Coyote Creek

May 2013 (38.11389 Degrees, -120.45278 Degrees) Douglas Flat Bridge

Continuing north along Coyote Creek we came to an old (1935) steel girder bridge with a timber deck. The Douglas Flat Bridge (30C0021) is a two span, 40 ft long, steel stringer bridge on end diaphragm abutments and a pier wall.

The bridge is 11.8 feet wide, carries about 50 vehicles a day, and has a sufficiency rating of 22.

Calaveras County, California Bridges; Douglas Flat Bridge across Coyote Creek by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Placer County, California's Bridges: State Route 49 Bridge across the North Fork of the American River

November 2012 (38.9155 Degrees, -121.0404 Degrees) State Route 49 Bridge

The next two bridges straddle the Placer/El Dorado County Line because the Middle Fork (the natural border between the counties) joins the North Fork just upstream of today's bridge.

The State Route 49 Bridge (19 0035) crosses what is still called the North Fork south of the confluence of the two rivers. It is a three span steel stringer bridge on concrete pier walls and seat-type abutments. It is 348.1 ft long with a 173.9 ft center span across the river.

We can see the remains of the previous bridge (from 1948) lying in the river beneath the current bridge (from 1965). I recall a big flood in 1964 that caused a lot of damage all along the west coast of the US.

In the photo above, we can see that the State Route 49 ends in a 'T at the end of the bridge. Travelers can make a left to continue on State Route 49 north into Nevada County or make a right onto old Foresthill Road that takes them east along the canyons of the North Fork of the American River to Soda Springs.

Placer County, California's Bridges: State Route 49 Bridge across the North Fork of the American River by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License.

Placer County, California's Bridges: Old Foresthill Road Bridge (2)

November 2012 (38.9166 Degrees, -121.0360 Degrees) Old Foresthill Road Bridge

The North Fork of the American River merges with the Middle Fork just downstream from today's bridge. This is a five span steel girder bridge on tall, hammerhead single column bents. The river must get very high to need such tall bents. Perhaps the last bridge at this site was washed away. 

On the Google earth photo below, we can see that the Old Foresthill Road makes an almost 180 degree turn as it crosses the North Fork of the American River. Thus, the Old Forest Hill Road Bridge is on a small radius horizontal curve. The Middle Fork of the American River flows just south of the bridge and it also marks the southern border for Placer County.

Placer County, California's Bridges: Old Foresthill Road Bridge (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License.

Ibaraki, Japan's Bridges: The Hatasome Bridge across the Satogawa (2)

June 2011 (36.536 Degrees, 140.540 Degrees) Hatasome Bridge

It may seem strange to shore up a bridge, remove the existing abutments and piers, and pour a new substructure in its place, but it's probably a lot less trouble then finding a place to put the girders while you rebuild.

It looks like they used the existing foundations, which remained undamaged (although either they moved or the ground around them moved as seen in the photo below).

Ibaraki, Japan's Bridges: The Hatasome Bridge across the Satogawa (2) by Mark Yashisnky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Ibaraki, Japan's Bridges: The Hatasome Bridge across the Satogawa (1)

June 2011 (36.536 Degrees, 140.540 Degrees) Hatasome Bridge

The Hatasome Bridge is a110.9 meter long, five span steel girder bridge on pier walls next to a footbridge. It was built in 1951 and it's also over the Satogawa River. Both this bridge and the previously studied Satogawa Bridge experienced strong shaking and damage during the earthquake. In this photo (three months after the earthquake) the superstructure is on shoring, all the piers have been removed, and some piers have been replaced while other piers (and the abutments) are about to be cast. 

Ibaraki, Japan's Bridges: The Hatasome Bridge across the Satogawa (1) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Ibaraki, Japan's Bridges: Rokko Bridge across Kitaura Lake (4)

June 2011 (36.086 Degrees, 140.540 Degrees) Rokko Bridge

A last look at the partially collapsed Rokko Bridge (on our left) and the new bridge being constructed on our right. Geotechnical engineers often measure the width of cracks on the river bank to determine how much lateral spreading occurred during an earthquake. However, if there was lateral spreading at this site, it must have occurred in the middle of the lake.

Perhaps there was just a loss of bearing capacity during the earthquake that allowed the pile bents to sink below the water's surface. My feeling is that this is an old, locally owned bridge that wasn't designed or retrofit to the standards of Japan's highway bridges.

Ibaraki, Japan's Bridges: Rokko Bridge across Kitaura Lake (4) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Ibaraki, Japan's Bridges: Rokko Bridge across Kitaura Lake (3)

June 2011 (36.086 Degrees, 140.540 Degrees) Rokko Bridge

The Rokko Bridge is so skinny that I would imagine most people used a wider bridge to cross the lake (there are several locations where the bridge is wider to accomodate passing vehicles).

The approach settled about a meter but the pile bents held the bridge up (except where they disappeared in the middle of the lake). You can see the new bridge they were building at the time of the earthquake on the right. If you go to Google Earth, you can see that the new bridge now looks complete while the old bridge still is sitting with three spans missing. Maybe the authorities are considering what to do (if anything) about the old bridge.

Prof Fujino had us pose in front of the dropped spans for a group photo with his colleagues. It may seem a little strange posing in front of a collapsed bridge, but it took considerable effort for us (especially me) to get to this spot. There were only two bridges that collapsed due to ground shaking during the 2011 Tohoku Earthquake and the other bridge was in Fukushima Prefecture (where we weren't allowed to go).

Ibaraki, Japan's Bridges: Rokko Bridge across Kitaura Lake (3) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Ibaraki, Japan's Bridges: Rokko Bridge across Kitaura Lake (2)

June 2011 (36.086 Degrees, 140.540 Degrees) Rokko Bridge

The Rokko Bridge lost two piers and three spans during the Tohoku Earthquake. Apparently the pipe piles weren't driven deep enough through the liquefiable soil. The bridge crosses a very long lake and so we had an hour’s drive to look at both approaches. There is a new bridge being built across the lake, but for now there is a long detour for people using Route 354.


A driver was going across the bridge and drowned when he drove off the bridge. He must have come from the north because the south approach had over a meter of settlement. The photo below shows details of the damage to the end diaphragm and bearings as the spans in the center of the lake were dragged away during the earthquake.

Ibaraki, Japan's Bridges: Rokko Bridge across Kitaura Lake (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Ibaraki, Japan's Bridges: Rokko Bridge across Kitaura Lake (1)

June 2011 (36.086 Degrees, 140.540 Degrees) Rokko Bridge

The Rokko Bridge is a 405 m long steel girder bridge on piers composed of four battered steel piles.  The approaches settled (see photo below) and the bridge lost two piers and three spans during the Tohoku earthquake. This was similar to the damage that occurred to the Showa Bridge during the 1964 Niigata earthquake and probably had the same cause: loss of strength and stiffness of the soil due to liquefaction.

Ibaraki, Japan's Bridges: Rokko Bridge across Kitaura Lake (1) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Tokyo, Japan's Bridges: Yanagishima Bridge across the Yoko Jikkengawa

March 2012 (35.708 Degrees, 139.819 Degrees) Yanagishima Bridge

Another view of the Yanagishima Bridge as we turn towards the Yoko Jikkengawa Canal. This bridge is about 80 ft wide and so the steel girder spans are supported by multicolumn, reinforced concrete bents. A blue water main is on the south side of the bridge. The recently studied Pedestrian Overcrossing and the Jikken Bashi can be seen in the Google Earth photo below.

Tokyo, Japan's Bridges: Yanagishima Bridge across the Yoko Jikkengawa by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Japan's Bridges: Kouzaki Bridges across Tonegawa in Ibaraki

June 2011 (35.9105 Degrees 140.396 Degrees) Kouzaki Bridges

Today we went to Ibaraki Prefecture to look at bridge damage from the March 11, 2011 Tohoku Earthquake. Japan is divided into prefectures like Ibaraki and also into regions like Kanto, Kansai, and Tohoku, which is in northeast Honshu (one of the four islands in Japan).

The Kousaki Bridges had minor damage from an earthquake that stretched 700 km from Iwate Prefecture in the northeast to Chiba Prefecture in the southwest.  The bridges were open for two months and then an engineer discovered some of the piles were broken (due to lateral spreading) and closed the highway bridge (the pedestrian bridge remains open).

Japan's Bridges: Kouzaki Bridges across Tonegawa in Ibaraki by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.

Alaska's Bridges: Salcha River Bridge

December 2002 Salcha River Bridge on Richardson Highway (lat. 64.470· long. -146.932·)

Alaska's Bridges: Salcha River Bridge in Alaska by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.