Hidden Wonders | A Trail Through Japan's Railway Engineering Legacy

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The Shinetsu Line once connected the Tokyo metropolitan area with Nagano and the Sea of Japan coast. At the border between Gunma and Nagano prefectures lay the Usui Pass, where gradients reached 6.67%, making it one of the steepest railway routes in Japan.

To tackle this formidable obstacle, engineers adopted the Abt rack railway system. A toothed rack rail was installed between the running rails, allowing specially equipped locomotives with cogwheels mounted underneath to push or pull trains up the slope.

The Abt section was abandoned in September 1963 after a new alignment opened. Today, the former route has been converted into a walking trail called the Abt no Michi (Abt Trail). Its surviving bridges and tunnels stand as a testament to the ingenuity of the engineers and railway workers who conquered this rugged mountain pass.

*A series of tunnels line the Abt Trail.*

A Historic Mountain Line

The section between Yokokawa in Gunma Prefecture and Karuizawa in Nagano Prefecture, popularly known as "Yokokaru," opened in 1893. The 11.2-kilometer route climbed gradients of up to 6.67%. Trains traversing the pass were assisted by dedicated locomotives specially designed for the climb.

The Abt Trail begins in front of Yokokawa Station. Following the straight uphill path alongside the tracks of the sightseeing trolley train operated from Usui Pass Railway Heritage Park, visitors soon reach the brick-built former Maruyama Substation, about 1.6 kilometers from the station.

*At Usui Pass Railway Heritage Park, visitors can see the rails of the Abt rack railway.*

Constructed in 1912 when the Yokokaru section was electrified, the substation consists of a machine room and battery room and is designated an Important Cultural Property of Japan. Its elegant architecture reflects the significance and prestige the route once held.

Walking the Abt Trail

Farther along, near the hot spring facility Toge no Yu, where the trolley train now terminates, the old Abt route diverges from the newer non-Abt alignment. The Abt Trail follows the former route from here.

After passing through five tunnels, the trail opens onto the famous Megane Bridge ("Spectacles Bridge"), officially known as the Usui Third Bridge and another Important Cultural Property.

The structure is a four-arch brick viaduct measuring 91 meters in length and 31 meters in height. Built using more than two million bricks, it remains one of Japan's most impressive works of railway engineering.

*"Megane Bridge" is made of more than two million bricks.*

From the bridge, visitors can see the viaduct of the newer line that opened in July 1963. Though it still looks as though trains might appear at any moment, this line was also abandoned in 1997 when the Hokuriku Shinkansen reached Nagano, ending conventional rail service across the pass.

*From Megane Bridge, the remains of the newer line (discontinued in 1997) can be seen.*

The End of the Trail

The Abt Trail ends at the former Kumonotaira Signal Station, about six kilometers from Yokokawa Station. It once served as the junction between the old and new lines and for a time functioned as a station as well; remnants of the platform remain. The nearby Kumonotaira Substation continued operating until the newer line closed.

The tunnels toward Yokokawa and Karuizawa, where the rails still remain, are normally off-limits but can be visited during special events organized by the Annaka City Tourism Organization.

Descending the stairs from the former signal station leads to the national highway. During the tourist season, local buses following the former Yokokaru route detour via Megane Bridge, offering a convenient option for hikers returning from the trail.

*Remnants of a substation at the former Kumonotaira Signal Station.*

Three Eras of Railway Travel

During the non-electrified era of the Abt railway, the journey between Yokokawa and Karuizawa took around 80 minutes. Electrification reduced that to 49 minutes, and the newer alignment shortened it further to just 17 minutes uphill and 24 minutes downhill.

Today, passengers on the Hokuriku Shinkansen can reach Annaka-Haruna, the next stop beyond Karuizawa, in under 10 minutes.

The old line, the newer line, and the Shinkansen each belong to a different era of railway technology, marking the passage of time at ever-increasing speeds.

When the Yokokawa-Karuizawa section first opened as an Abt railway, it was not electrified. Steam locomotives hauled trains across the pass, but the numerous tunnels caused serious problems with smoke and soot.

To address this issue and increase capacity, the line was electrified in 1912. Electric locomotives were initially imported from Germany, but domestic manufacturers soon produced Japanese-built versions based on those designs. One was the ED42 class, examples of which are preserved at Usui Pass Railway Heritage Park near Yokokawa Station.

*The ED42 electric locomotive, built for Usui Pass, is on display at Usui Pass Railway Heritage Park.*

Introduced in 1934, the ED42 remained in service until the Abt system was abolished in 1963. For a time, it even headed the famous diesel-powered limited express Hakucho, inaugurated in 1961 and running between Osaka and Ueno via the Hokuriku and Shinetsu lines.

The park also displays the EF63 electric locomotive, built for the new line that opened in 1963, along with 189-series Asama limited express trains, which relied on EF63 helper locomotives to cross the pass.

Beyond its railway vehicle exhibits, the park offers trolley train rides to Toge no Yu and driving experiences aboard an EF63 locomotive.