The headwaters of the Shimanto River start in Miyama and it winds 196 kilometers down into Tosa Bay.
Throughout Japan it is affectionately called “the clear river”.
The Chinkabashi bridge is famous for its special design.
It has no railings, and sinks with the water level to prevent it being washed away when the river floods.


http://www.city.shimanto.lg.jp/simanto/chinka/misato.jpg

http://www.city.shimanto.lg.jp/simanto/chinka/takase.jpg

http://static.flickr.com/215/484952324_a113e63046.jpg

http://www.civil.kumamoto-u.ac.jp/river/gallery/image-0/nakahage-3.jpg

http://www.water-e.co.jp/kyukei01/images/img001.jpg

http://fukuiten-yoo.web.infoseek.co.jp/gallery/ds17/bg-13.jpg

http://www.attaka.or.jp/photoDB/5715ba814d5ac8d54caf847d0bd7eb80/b5159e3562e8c0cfdadb72ad936f2192/40861c01819ed05bbf05a0d861cc0567.jpg


http://photoimg.enjoyjapan.naver.com/view/enjoybbs/viewphoto/ptravel/56000/20070919119021180954249400.jpg

http://upload.wikimedia.org/wikipedia/ja/3/32/Sata-chinka2.jpg

The river also has 67
chinkabashi (沈下橋 'sinking bridge') including those of tributaries in kochi pref. Chinkabashi are bridges without parapets in order not to be washed away by floods. The prefecuture decided to preserve them as cultural heritages.
there are also 68 chinkabashi in Oita pref.

That's really interesting. I've been interested in bridges for many years, but I've never heard of these. Thank you for sharing them with us.

Wow, that really is interesting. Are there any photos of these actually submerged?

Also, are they regulated? Is there a point when traffic is no longer allowed to cross or is it at the driver's discretion? Finally, how often does the water reach the road and/or submerge it?

Thank you for posting this, it is very interesting!!

But if the bridge goes under water, can it not then be flushed away?

Thanks for sharing these great pictures ! A question though : in which prefecture do you find these bridges ? Near the Japanese Alps ?

There are two bridges like this in my city - The river is smaller than those, but it does occasionally flood. Even when it's just unusually deep, the bridges can get flooded. But since they're very stoutly built - a pair of concrete blocks set into the riverbed with a series of big metal pipes to let the water through - they don't get washed away in floods. The bridges used to be open to car traffic one-way, but the road had to be demolished to make way for a flood-control project, so now it's foot traffic only. There wasn't much traffic to begin with, because the road just went through a park and there are higher-capacity roads going the same direction nearby.

I've just come back from a trip to Shikoku was just doing a search to find our about Chinkabashi and this thread is the top search result.
Here's a photo of one of the bridges on the Shimanto river in Kochi prefecture when submerged. This is at Katsuma,
https://picasaweb.google.com/lh/photo/41n1L2xgXN7aQyLQ1UOtTs8dTXVtp1EWL-_WU3LeIH4?feat=directlink


and this is another one slightly less submerged

https://picasaweb.google.com/lh/photo/oQ5Qfg1hQJyGC0-mjvbXCc8dTXVtp1EWL-_WU3LeIH4?feat=directlink

and I found the Japanese Wiki very good for more examples http://ja.wikipedia.org/wiki/%E6%B2%88%E4%B8%8B%E6%A9%8B