The Line's Other Five-Centred Arch

The Kumagawa Railway Hirahara Arch Bridge (くま川鉄道平原アーチ橋) is a concrete arch in Hirahara, Taragi Town, Kuma District, Kumamoto Prefecture, completed in 1924 and registered as a Registered Tangible Cultural Property on 19 December 2014. It is 3.7 metres long and 8.1 metres wide, about 2 kilometres north-east of the Miyata Bridge.

It is a small arch carrying water under the railway, with a span of 6 feet. The only other arch among the registered structures is the Iwashimizu Arch Bridge in Hitoyoshi.

A Skewed Arch with an Invert

The profile follows circular No. 1007, the standard five-centred arch: arcs from five centres joined into an outline that rises higher at the crown than a semicircle and has a distinctive look.

The Kumagawa Railway Hirahara Arch Bridge is built as a skew bridge, the whole arch set at an angle to the track. Its floor is lined with concrete, known as an invert, to protect the bed, and stone wing walls flank the abutments. It was registered as difficult to reproduce.

The Iwashimizu Arch Bridge, built to the same No. 1007 design, runs 43 metres through a large embankment. Set against the 8.1-metre width here, it shows one standard design stretched or shortened to suit the size of the bank above.

What to Look For

Look for the five-centred outline of the portal and the skewed axis of the arch. Standing square in front of the portal, you cannot see straight through to the far end, because the bore runs at an angle to the track.

In dry spells the concrete invert may be visible on the floor. Note, too, where the concrete portal meets the stone wing walls.

Visiting

The Kumagawa Railway Hirahara Arch Bridge is part of a working line, and the track and embankment are off limits. View the portal from nearby, free of charge. It lies between Taragi and Taragi-Shorenji (formerly Higashi-Taragi) stations, about 1.2 kilometres west of Taragi-Shorenji. Adult fares from Hitoyoshi Onsen are 590 yen to Taragi and 650 yen to Taragi-Shorenji.

Stay out of the watercourse, the fields and private land.

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Q&A

QWhere is the Kumagawa Railway Hirahara Arch Bridge?
AIn Hirahara, Taragi Town, between Taragi and Taragi-Shorenji stations, about 1.2 kilometres west of Taragi-Shorenji.
QWhat kind of structure is the Kumagawa Railway Hirahara Arch Bridge?
AA concrete single arch of 1924, 3.7 metres long and 8.1 metres wide, with a 6-foot span.
QWhat should I look for at the Kumagawa Railway Hirahara Arch Bridge?
AThe five-centred arch outline to design No. 1007, the skewed axis, and the concrete invert on the floor.
QHow does the Kumagawa Railway Hirahara Arch Bridge differ from the Iwashimizu Arch Bridge?
ABoth are five-centred No. 1007 arches, but Iwashimizu runs 43 metres through a large embankment, while Hirahara is a skewed arch 8.1 metres wide.
QCan I take photographs of the Kumagawa Railway Hirahara Arch Bridge?
ANo specific restriction on photography from public roads and other permitted places has been announced. Do not enter the track, fields or private land. Commercial filming and press coverage go through the Kumagawa Railway's filming and coverage request page.

Basic Information

NameKumagawa Railway Hirahara Arch Bridge (くま川鉄道平原アーチ橋)
LocationHirahara, Taragi, Taragi Town, Kuma District, Kumamoto Prefecture
DesignationRegistered Tangible Cultural Property (structure), registration No. 43-0144
Year DesignatedRegistered 2014/12/19 (Heisei 26)
Quantity1 structure
DimensionsConcrete single-arch bridge, 3.7 metres long, 8.1 metres wide, with wing walls
OwnerKumagawa Railway Co., Ltd.
Public AccessIn railway service; no access to the track or embankment, the arch portals can be viewed from nearby

References

National Cultural Properties Database, Agency for Cultural Affairs: Kumagawa Railway Hirahara Arch Bridge
https://kunishitei.bunka.go.jp/heritage/detail/101/00010401
Kumagawa Railway: Historic and Cultural Heritage
https://kumagawa-rail.com/cultural-property/
Kumagawa Railway: Timetable and Fares
https://kumagawa-rail.com/time-fare/

Last verified: 2026.09.24