A Low-Water Bridge on the Yusuhara River
The Koyagauchi Bridge (木屋ヶ内橋) is a reinforced concrete low-water bridge of 1953 in Koyagauchi, Shimanto Town, Takaoka District, Kochi Prefecture, and was registered as a Registered Tangible Cultural Property (structure) on March 7, 2008 (Agency for Cultural Affairs).
The Agency records a four-span reinforced concrete girder bridge, 27 metres long and 3.0 metres wide; registration number 39-0246.
A Low-Water Bridge on the Yusuhara River
The Koyagauchi Bridge is a low-water bridge, built to be submerged in floods, over the lower Yusuhara River in the Shimanto River system. It is a four-span reinforced concrete girder bridge set on bedrock, with its longest span, 8 metres, near the middle of the stream (Agency for Cultural Affairs).
Such bridges are built low and without parapets so that floodwater passes over them. Kochi Prefecture includes this one in its list of the low-water bridges of the Shimanto River.
Why It Was Registered
The Agency notes the care taken for floodwater, with sharply pointed cutwaters on the upstream side and curved faces on both sides of the girders, and registered it for its contribution to the historic landscape.
What to Look For
Look for the pointed cutwaters on the upstream side and the curved faces of the girders (Agency for Cultural Affairs). About 100 metres to the south is the Koyagauchi Tunnel of the former Taisho forest railway, registered on the same day.
Visiting
It is owned by Shimanto Town (Agency for Cultural Affairs). Low-water bridges become impassable in floods, so take care in wet weather. No official visiting information was found.
Q&A
- When was the bridge built?
- In 1953 (Agency for Cultural Affairs).
- What is a low-water bridge?
- A low bridge without parapets, built so that floods pass over it.
- What should I look for?
- The pointed cutwaters and the curved faces of the girders.
- Where is it?
- Over the lower Yusuhara River in Koyagauchi, Shimanto Town, Kochi Prefecture.
- When was the Koyagauchi Bridge registered?
- On March 7, 2008 (Agency for Cultural Affairs).
Basic Information
| Name | Koyagauchi Bridge (木屋ヶ内橋) |
|---|---|
| Location | Koyagauchi, Shimanto Town, Takaoka District, Kochi Prefecture |
| Designation | Registered Tangible Cultural Property (Structure) |
| Year Designated | Registered 2008/03/07 (Heisei 20) |
| Quantity | 1 structure |
| Dimensions | Reinforced concrete 4-span girder bridge, 27 m long, 3.0 m wide |
| Owner | Shimanto Town |
| Public Access | Low-water bridge (closed in floods; no official visiting information) |
References
- Koyagauchi Bridge (Database of National Cultural Properties, Agency for Cultural Affairs)
- https://kunishitei.bunka.go.jp/heritage/detail/101/00006947
- Low-water bridges of the Shimanto River (Kochi Prefecture, Japanese)
- https://www.pref.kochi.lg.jp/doc/2017100600137/file_contents/file_2016427315368_1.pdf
Last verified: 2026.10.20