The Smallest Arch on the Line
The Former JNR Shihoro Line Isamigawa Bridge (旧国鉄士幌線勇川橋梁) is a small concrete arch bridge of 1936 in Kamishihoro, Kato District, Hokkaido, and was registered as a Registered Tangible Cultural Property (structure) on August 23, 1999 (Agency for Cultural Affairs).
The Agency records a concrete arch bridge 4 metres long overall; registration number 01-0010.
A Culvert Under the Embankment
The Former JNR Shihoro Line Isamigawa Bridge is a concrete culvert bridge that carried a small stream under the railway embankment (Agency for Cultural Affairs). The section from Kamishihoro to Tokachi-Mitsumata was built as the Otofuke Line and opened in 1939; the Isamigawa Bridge was built during that work, in 1936.
The name is read Isamigawa (Agency for Cultural Affairs). It stands in the 黒石平 district of Kamishihoro, the same area as the much larger Third Otofuke River Bridge.
Why It Was Registered
The Agency counts the Isamigawa Bridge among the Higashi-Taisetsu railway arch bridges and notes that, though only 4 metres long, its arch follows a parabolic curve rather than a simple circle. It was registered for its contribution to the historic landscape.
The long arches over the larger rivers draw most of the attention on this line. The Isamigawa Bridge shows that the builders gave even a small stream crossing a carefully shaped arch.
What to Look For
The thing to look for is the line of the arch, which traces a parabola rather than a half circle (Agency for Cultural Affairs). It rises more steeply towards the crown than a round arch would.
It shares a district with the 71-metre Third Otofuke River Bridge, and the contrast shows how the size of each bridge on the line followed the size of the water it crossed.
Visiting
It is a small culvert under the embankment, and no official information on a viewing path or signboard was found. Published sources do not confirm whether it can be seen from the road.
This is also brown bear country, so take great care if you go down to the stream.
Q&A
- How is the Isamigawa Bridge name read?
- Isamigawa (Agency for Cultural Affairs).
- When was the Former JNR Shihoro Line Isamigawa Bridge built?
- In 1936 (Agency for Cultural Affairs).
- How big is the Isamigawa Bridge?
- It is a small concrete arch bridge, 4 metres long overall.
- What is special about the Isamigawa Bridge?
- Its arch follows a parabolic curve rather than a circle (Agency for Cultural Affairs).
- When was the Former JNR Shihoro Line Isamigawa Bridge registered?
- On August 23, 1999 (Agency for Cultural Affairs).
Basic Information
| Name | Former JNR Shihoro Line Isamigawa Bridge (旧国鉄士幌線勇川橋梁) |
|---|---|
| Location | Lots 48-2 and 49, Kamishihoro, Kato District, Hokkaido |
| Designation | Registered Tangible Cultural Property (Structure) |
| Year Designated | Registered 1999/08/23 (Heisei 11) |
| Quantity | 1 structure |
| Dimensions | Concrete arch bridge, 4 m long overall |
| Owner | Kamishihoro Town |
| Public Access | No official viewing information |
References
- Former JNR Shihoro Line Isamigawa Bridge (Database of National Cultural Properties, Agency for Cultural Affairs)
- https://kunishitei.bunka.go.jp/heritage/detail/101/00001210
Last verified: 2026.10.19
