Jomo Electric Railway Ogo Station Substation

Jomo Electric Railway Ōgo Station Substation: A Living Monument to Early Railway Electrification

Tucked beside the tracks of the Jomo Electric Railway in Maebashi, Gunma Prefecture, the Ōgo Station Substation stands as a quiet yet powerful testament to Japan's early era of railway electrification. Built in 1928 — the same year the Jomo Line opened for service — this reinforced concrete building has been converting high-voltage alternating current into the direct current that powers trains for nearly a century. Registered as a national Tangible Cultural Property in 2007, the substation is one of several historically significant structures at Ōgo Station that together form a remarkable complex of early Showa-era railway heritage.

A Brief History of the Jomo Electric Railway and Ōgo Station

The Jomo Electric Railway Company was founded in 1926 with the aim of connecting the cities of Maebashi and Kiryū in Gunma Prefecture. The 25.4-kilometer Jomo Line opened on November 10, 1928, electrified from the start at 1,500 volts DC. The railway was born out of the region's thriving silk industry — Maebashi was a major silk-producing center, while Kiryū was renowned for its textile weaving — and the line was designed to facilitate the transport of silk and passengers between these two important cities at the foot of Mount Akagi.

Ōgo Station, located 8.3 kilometers from the Chūō-Maebashi terminus, was established as one of the original eighteen stations when the line opened. From the beginning, Ōgo served as the railway's central operational hub. The station was chosen as the site for the company's sole vehicle depot (the Ōgo Carriage Shed), along with the critical electrical infrastructure needed to power the trains — including the substation that is the subject of this article.

The Substation: Architecture and Engineering

The Ōgo Station Substation is a single-story reinforced concrete building with a partial basement level. At the time of its construction in 1928, it was reportedly the only reinforced concrete structure in the entire Seta District of Gunma Prefecture — a remarkable fact that underscores its significance as an example of modern construction technology arriving in rural Japan.

The exterior walls are finished with mortar rendering. Originally, the building bore no paint, presenting a natural brown appearance characteristic of its concrete and mortar surfaces. Over the decades, as surface cracking became evident, repairs and exterior painting were carried out in 2004 (Heisei 16) to preserve the structure. The roof, initially treated only with waterproofing over mortar, has since been covered with corrugated metal sheeting for improved weather protection.

The northern section of the building was not part of the original 1928 construction. It was added in 1943 (Showa 18) as a wartime measure. With the company's headquarters in central Maebashi at risk of air raids, this extension was built to accommodate the potential relocation of head office functions. Indeed, during the war and for a period afterward, some of the company's administrative operations were transferred to this substation building — a fascinating chapter that reveals how infrastructure served multiple purposes during Japan's wartime era.

How the Substation Works

The primary function of the Ōgo Station Substation is to convert electrical power for railway use. The facility receives 60,000-volt alternating current from the main power grid and transforms it down to 1,500 volts of direct current, which is then fed into the overhead wire system to power the trains running along the Jomo Line. This conversion process — from high-voltage AC to low-voltage DC — is fundamental to the operation of electric railways, and the Ōgo substation has been performing this vital role continuously since 1928.

Beyond railway operations, the substation also served as a regional power distribution facility until the 1950s. During that era, it supplied electrical current to the surrounding communities of Ōgo, Miyagi, and Kasukawa — a reminder of the broad social impact that railway electrification had on rural communities in the early twentieth century.

Why It Was Designated a Registered Tangible Cultural Property

On July 31, 2007, the Ōgo Station Substation was officially registered as a national Tangible Cultural Property by the Agency for Cultural Affairs. It was part of a group designation that included several other structures at the station: the station building, the train garage (carriage shed), a transformer house, an electrical transmission tower, an overhead electrical transmission tower, and an electrical wire retention tower.

The substation's designation recognizes several layers of historical and architectural value. As a rare surviving example of early Showa-era railway electrical infrastructure, it demonstrates the engineering standards and construction techniques of Japan's interwar period. The fact that it was the first reinforced concrete building in its district highlights its role as a pioneer of modern construction in rural Gunma. Its wartime extension tells the story of how civilian infrastructure adapted to the pressures of World War II. And its continued operational use — still converting power for the trains that pass through Ōgo Station every day — makes it a living piece of industrial heritage rather than a mere museum exhibit.

The entire Ōgo Station complex has also been recognized as a Gunma Prefecture Modernization Heritage site and received the Japan Society of Civil Engineers' Heritage Award, further affirming its importance in Japan's industrial and engineering history.

Highlights and Things to See

A visit to Ōgo Station offers much more than the substation alone. The entire station complex is a remarkably well-preserved collection of structures dating from the railway's 1928 opening, and together they create an atmosphere that transports visitors back to the early Showa era.

The Ōgo Carriage Shed (Train Garage)

Adjacent to the substation, the Ōgo Carriage Shed is a wooden, board-clad building featuring a truss roof structure that provides the wide, column-free interior space needed to house railway vehicles. Inside, visitors can see rare rolling stock including the DeHa 101 and DeHa 104 electric railcars — original 1928 vehicles that served as the railway's mainline fleet until the 1970s — as well as the DeKi 3021 electric locomotive and a Te 241 freight car. The shed can be visited by prior reservation (see details in the Basic Information section below).

The Station Building

The Ōgo Station building itself retains much of its original character. Originally comprising a waiting room, parcel office, ticket office, wicket gate, and staff quarters, it has been adapted over the decades while maintaining its historic wooden architecture and nostalgic ambiance.

Seasonal Events

The Jomo Electric Railway hosts popular public events at the Ōgo depot, typically in spring and autumn. These events offer special access to the carriage shed, rides behind the vintage DeKi 3021 electric locomotive, train driving simulator experiences, and even tug-of-war competitions with railroad equipment. The spring event and the autumn Appreciation Event are beloved traditions that draw railway enthusiasts and families from across the region. A special chartered ride on the historic DeHa 101 railcar is sometimes offered during these events.

Nearby Attractions

Ōgo Station is well positioned as a gateway to the southern slopes of Mount Akagi and offers convenient access to several appealing destinations in the area.

• Gunma Flower Park + (ぐんまフラワーパークプラス): Reopened in October 2025 after a major renovation, this expansive 18.4-hectare park on the slopes of Mount Akagi features seasonal flower displays, greenhouses, an English garden, a Japanese garden, and interactive nature experiences. Accessible from Ōgo Station by demand bus (approximately 15 minutes).
• Akagi Nanmen Senbonzakura (赤城南面千本桜): A famous 1.3-kilometer avenue of roughly 1,000 cherry trees on the southern face of Mount Akagi, offering spectacular hanami (cherry blossom viewing) from early to mid-April.
• Ōgo Green Flower Farm (大胡ぐりーんふらわー牧場): A roadside station and agricultural park near Ōgo with farm animals, playgrounds, and local produce.
• Akagi Shrine (赤城神社, Sanyazawa): A historic Shinto shrine nestled in the foothills of Mount Akagi, known for its tranquil forest setting and ancient atmosphere.
• Nishi-Kiryū Station (西桐生駅): At the other end of the Jomo Line, this station features a charming Mansard-roofed Western-style wooden building from 1928, also registered as a Tangible Cultural Property — making a full journey along the line a rewarding heritage experience.

Access and Getting There

Ōgo Station is located on the Jomo Electric Railway Jomo Line, approximately 20 minutes by train from the Chūō-Maebashi terminus. From central Tokyo, the most convenient route is to take the JR Takasaki Line or Shinkansen to Takasaki Station, transfer to the JR Ryōmō Line to Maebashi Station, then take a short bus or taxi ride to Chūō-Maebashi Station (the Jomo Line terminus). Alternatively, the Tōbu Railway's limited express "Ryōmō" runs from Asakusa (Tokyo) to Akagi Station, which is on the Jomo Line east of Ōgo.

The Jomo Electric Railway offers an all-day unlimited ride pass, which is excellent value for visitors who wish to explore multiple stations along the line. Bicycles can be brought aboard the trains, making it easy to cycle to nearby attractions such as Gunma Flower Park from Ōgo Station.