How a Japanese mountain railway conquered steep slopes using Swiss-inspired engineering and switchbacks

Society · Published 9 October 2026 Swipe more like this →

In short: The Hakone Tozan Line is not just a transit route; it is a masterclass in navigating extreme topography. Spanning 15 kilometers, this railway climbs over 500 meters into the mountains. By utilizing sharp curves, steep gradients, and clever switchbacks, it connects the coast to the highlands of Fuji-Hakone-Izu National Park.

The Hakone Tozan Line, located in Kanagawa Prefecture, is a tale of two distinct railway experiences. While the lower section from Odawara to Hakone-Yumoto functions as a standard-gauge extension of the Odakyū Odawara Line, the upper mountain section requires a complete change of trains. This upper segment, which ascends to Gōra, is specifically engineered for the rugged terrain, featuring gradients as steep as 8% and curves with a minimum radius of 169 meters. To manage these vertical challenges, the line employs three switchbacks, where trains reverse direction to gain elevation.

The railway's history reflects Japan's rapid modernization. It began in 1888 as a horse-drawn tramway before transitioning to electricity in 1900. By 1919, the mountain section opened, fundamentally changing access to the Hakone region. Over the decades, the line has undergone significant technical upgrades, including increasing electrification voltage from 600 V DC to 750 V DC in 1993 to support longer three-car electric multiple units. The line has also proven resilient; after Typhoon Hagibis caused severe damage in October 2019, including washed-away track ballast and landslides, full service was restored by July 2020.

Today, the line is operated by Odakyu Hakone Co., Ltd., a subsidiary of the Odakyu Group. The mountain section maintains a distinct identity, with rolling stock series named after Swiss counterparts, such as the 'Bernina' and 'St. Moritz' series, acknowledging the influence of mountain railway design. The infrastructure is carefully integrated into the landscape, designed to minimize environmental impact while providing essential transit through the Fuji-Hakone-Izu National Park. Passengers traveling from Shinjuku can even access the line via 'Romancecar' services, which continue directly to Hakone-Yumoto, bridging the gap between the bustling metropolis and the quiet mountain peaks.

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