Sending crumbling granite over the track
The Watarase Keikoku Railway Yoshinozawa Aqueduct is a railway structure of 1935 at Sori in Higashimachi, Midori City, Gunma Prefecture, listed as a Registered Tangible Cultural Property in 2009. A kakehi is a trough set on supports, and this one is thrown across the track itself, to stop rainwater and debris from reaching the rails.
The hillside here is granite, the stone quarried locally and known as Sori mikage. Granite weathers to coarse sand, and every heavy rain brings some of it down the slope. The Yoshinozawa Aqueduct gathers that sand and water together and carries them over the top of the line.
The construction is plain and hard to miss. A steel assembly of posts and girder made in one piece from second hand rail supports a reinforced concrete trough 14 metres long and 2.7 metres wide. Thin iron legs stand beside the track, a grey box crosses above them, and the result looks less like railway equipment than like a small aqueduct.
Protecting a line cut through stone country
What the Watarase Keikoku Railway Yoshinozawa Aqueduct shows is a direct answer to a specific piece of ground. Sori has long been known for its granite, and the railway runs along a slope cut into that rock. Faced with stone that is hard but weathers badly, the engineers chose neither a retaining wall nor a rockfall shed but a way of taking the water high and letting it pass overhead. The Teburiyama Aqueduct further down the line dates from 1930 and this one from 1935, the same idea applied to two very different slopes.
Registration came on 2 November 2009, with public notice on the 19th, when 38 structures from Kiryu to Mato were listed together. No Japanese line had previously been listed in full across two prefectures. The criterion was contribution to the historic landscape of the country, and the group was recognised as a Civil Engineering Heritage in 2016.
Four minutes out of Sori, short of the long tunnel
The Watarase Keikoku Railway Yoshinozawa Aqueduct stands about 1,000 metres southwest of the Kasamatsu Tunnel. Going north from Sori towards Mato it comes up about four minutes after departure; from Harumukai towards Kiryu the wait is roughly three and a half minutes. The train is past it in a second, so watch the upper part of the window once the hillside starts to look pale.
That pallor is weathered granite, and against it the rusted supports and the grey trough draw a level line. For a moment the underside of the trough passes directly overhead. Some 1,400 metres back to the south lies the Nagoshi Tunnel; ahead is the Kasamatsu Tunnel, the longest bore on the line.
Visiting
The Watarase Keikoku Railway Yoshinozawa Aqueduct is part of a working railway and the track area is closed, so it is seen from trains between Sori and Harumukai. Since it passes overhead, an open sided Torokko carriage gives the clearer view. Those trains require a Torokko seat coupon in addition to the ordinary fare, priced from 1 September 2026 at 700 yen for adults and 350 yen for children, and seats are worth reserving in advance.
The one day free pass, 1,880 yen for adults and 940 yen for children, suits a plan that involves getting off at Sori and waiting for the next service. The line runs 44.1 kilometres from Kiryu to Mato in about an hour and a half. Photography from inside the carriage is unrestricted, while drone filming of trains and the track area is prohibited. Ticket information is published by the operator; fares here were checked on 13 September 2026.
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Q&A
- What is the Watarase Keikoku Railway Yoshinozawa Aqueduct for?
- It keeps weathered granite sand and rainwater off the track by carrying them across the line in a trough set above the rails.
- How big is the Watarase Keikoku Railway Yoshinozawa Aqueduct?
- The reinforced concrete trough measures 14 metres by 2.7 metres, carried on a steel assembly whose posts and girder are made in one piece from old rail.
- When was the Watarase Keikoku Railway Yoshinozawa Aqueduct built?
- In 1935. It was listed in 2009 together with 38 structures along the line between Kiryu and Mato.
- Where is the Watarase Keikoku Railway Yoshinozawa Aqueduct seen from?
- From trains between Sori and Harumukai, about four minutes north of Sori or three and a half minutes from Harumukai heading south.
- What is the pale rock around the Watarase Keikoku Railway Yoshinozawa Aqueduct?
- Granite known as Sori mikage. It weathers into sand that slips down the slope, which is exactly what the aqueduct diverts.
Basic Information
| Name | Watarase Keikoku Railway Yoshinozawa Aqueduct |
|---|---|
| Location | Sori, Higashimachi, Midori City, Gunma Prefecture |
| Designation | Registered Tangible Cultural Property (structure) |
| Year Designated | Registered in 2009 (Heisei 21) |
| Quantity | 1 structure |
| Dimensions | Length 14 metres, width 2.7 metres |
| Owner | Not recorded in the Agency for Cultural Affairs database; the line is operated by Watarase Keikoku Railway Co., Ltd. |
| Public Access | Not open to entry; seen from passing trains |
References
- Agency for Cultural Affairs, National Cultural Properties Database: Watarase Keikoku Railway Yoshinozawa Aqueduct
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00007851
- Midori City: Yoshinozawa Aqueduct
- https://www.city.midori.gunma.jp/kosodate/1001647/1001800/1002430/1002480.html
- Watarase Keikoku Railway Co., Ltd.: cultural property leaflet
- https://www.watetsu.com/assets/pdf/sightseeing/culture_yukei_des05.pdf
- Watarase Keikoku Railway Co., Ltd.: one day free pass
- https://www.watetsu.com/rail-info/ticket_1dayfree.php
Last verified: 2026.09.13