A Curved Brick Bore Above the Watarase Gorge
Ninety-eight meters of single-track railway pass through solid rock here, on a slope above the Watarase River in Midori, Gunma Prefecture. The Dai-ichi Godo Tunnel is not straight. It bends in a gentle curve, so a passenger who looks ahead from the front of the train never sees daylight at the far end until the carriage is well inside. The lining is brick, laid four courses deep, a thickness that speaks to how much rock and rubble the builders expected the tunnel to hold back on this unstable mountainside.
The tunnel dates to 1912, the year the private Ashio Railway drove its line up the gorge to reach the copper mine at its head. Two later additions gave the structure the shape it has today. At the eastern portal stands a reinforced-concrete rockfall shelter, a hood built out over the track to catch stones tumbling from above, and its designers varied the thickness of the concrete ring along its length rather than pouring it to a single uniform section. A small plaque set into the shelter records the grade and quality of the materials used. At the western portal, a retaining wall of cobblestone runs on for thirty-one meters, holding the cutting open where the line emerges.
Why a Railway Tunnel Became a Cultural Property
Japan's Registered Tangible Cultural Property system, created in 1996, protects structures that are generally more than fifty years old and worth keeping, applying a lighter touch than the older "Important Cultural Property" designation. Rather than freezing a building in place, registration recognizes its value while allowing it to stay in everyday use. The Dai-ichi Godo Tunnel was registered on 2 November 2009, with the official notice following on 19 November, as one of roughly three dozen railway structures along this line entered together in the sixty-fifth round of registrations. The listed reason is straightforward: the tunnel contributes to the historic landscape of the country.
That landscape is a specific one. The line began as the Ashio Railway, laid to haul copper ore down from the Ashio mine in what is now Nikko. The mine had made Japan a major copper producer and had also caused one of the country's first industrial pollution disasters, the Ashio copper poisoning that scarred the Watarase valley. The railway was nationalized in 1918 and ran for decades as the government's Ashio Line. When the mine closed in 1973 the traffic fell away, and in 1989 the route passed to the third-sector Watarase Keikoku Railway, which runs it today as a scenic local line. The tunnels and bridges from 1912 survived because trains kept using them.
Seeing It From the Train
The best view of the Dai-ichi Godo Tunnel is from a carriage window. The line hugs the river through this stretch, and the run between Sori and Kobe stations crosses some of the most photographed scenery on the route, planted in recent years with hanamomo flowering peach that colors the banks in spring. The tunnel sits about 180 meters west of a companion, the Dai-ni Godo Tunnel, so the two arrive in quick succession, a brief plunge into brick-lined dark and out again.
The name preserves a piece of local history. "Godo" here is written with characters read as Godo but once attached to a station called Godo that was renamed Kobe when the private railway became the Watarase Keikoku line in 1989. The tunnel keeps the older spelling. Note that the tunnel is a working part of an active railway. It cannot be walked or entered, and the safe way to experience it is aboard a train, ideally one of the open-sided torokko sightseeing cars that the railway runs in the warmer months. For a longer look at the line's early engineering, the nearby Kobe station building, also from the Ashio Railway years, is worth a stop.
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Q&A
- Can I walk through or into the tunnel?
- No. It carries an active single-track railway and is not open to pedestrians. You can see it from a train on the Watarase Keikoku line.
- How old is the tunnel?
- The bore dates to 1912. The reinforced-concrete rockfall shelter and cobblestone retaining wall were added later, in 1929 and 1958.
- Why is it "Dai-ichi Godo" when the station is Kobe?
- The tunnel carries the older place name, Godo, that the station bore until 1989, when it was renamed Kobe. The two neighboring tunnels are numbered one and two.
- What is the best time of year to ride this section?
- Late spring, when the flowering peach along the Sori-to-Kobe stretch is in bloom, and autumn, when the gorge turns color. The torokko sightseeing trains run in these seasons.
Basic Information
| Name | Watarase Keikoku Railway Dai-ichi Godo Tunnel |
|---|---|
| Location | Godo, Azuma-cho, Midori City, Gunma Prefecture |
| Designation | Registered Tangible Cultural Property (registered 2 November 2009; notice 19 November 2009) |
| Registration No. | 10-0287 |
| Count | 1 structure |
| Date | 1912; additions 1929 and 1958 |
| Structure | Brick and stone construction, 98 m long, with rockfall shelter and retaining wall |
| Access | Viewable from trains on the Watarase Keikoku line; the tunnel itself is not open to the public |
References
- National Database of Designated Cultural Properties, Agency for Cultural Affairs — Watarase Keikoku Railway Dai-ichi Godo Tunnel
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00007860
- Watarase Keikoku Railway Co., Ltd. — Company History
- https://www.watetsu.com/company/history.php
- Watarase Keikoku Line (Japanese Wikipedia)
- https://ja.wikipedia.org/wiki/わたらせ渓谷鐵道わたらせ渓谷線
Last verified: 2026.07.02