Friday, November 25, 2011

Japan's Bridges: Naruse Okumatsushima Bridge in Miyagi Prefecture

June 2011 (38.414 Degrees, 141.141 Degrees) Naruse Arch Bridge
A little north (upstream) of today's bridge the Naruse and Yoshida Rivers come together and then flow side by side into the Pacific. Just south of the rivers' mouth, Japan's coastline undergoes a complete change from mountains to a flat plain. The fact that this is where the epicenter of the March earthquake occurred may just be a coincidence.

The Naruse Okumatsushima Bridge carries the Sanriku Expressway over the Yoshida and Naruse Rivers. The bridge includes a tied arch segment between the two river spans. The arch appears to be slightly kinked, it is tied to the closer pier with a steel cable, but this is apparently a design or construction problem.

When I first saw this bridge during a recent trip around Miyagi Prefecture I assumed the tilt to the arch was due to the earthquake. However, three or four different engineers assured me that this bridge has always been this way. I guess that a twisted arch is just as stable as a symmetric arch but it does seem odd.
Creative Commons License
Japan's Bridges: Naruse Okumatsushima Bridge in Miyagi Prefecture by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.

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