Toyohashi Main Line - Toyohashi Main Line

The name of the Kyushu Railway Company's track. The 148.0 km section between Kumamoto and Oita is single track. The 2.2 km section between Oita and Shimogori Signal Station is AC electrified. One of the Kyushu Trans-Kyushu railways. It runs from the Kumamoto Plain up the valley of the Shirakawa River, crosses the crater plain of Mt. Aso, crosses the watershed of the Aso outer rim, enters the Ono River basin, passes through the Takeda Basin and reaches the Oita Plain. For this reason, it is nicknamed the Aso Highlands Line. Construction began on the Oita side under the name Inukai Light Line (Inukai Line from 1922) and on the Kumamoto side under the name Miyaji Light Line (Miyaji Line from 1922), with the former running between Oita and Tamarai from 1914 to 1925 (Taisho 3-14), and the latter running between Kumamoto and Miyaji from 1914 to 1918. With the opening of the Tamarai-Miyaji section in 1928 (Showa 3), the two lines were linked and merged to become the Hohi Main Line. There is a section with a steep gradient of 33‰ (per mille) where it crosses the outer rim of Mt. Aso, and the scenery crossing the crater basin is magnificent. In 1987 (Showa 62), following the division and privatization of the Japanese National Railways, it became part of Kyushu Railway Company.

[Eiichi Aoki and Ryo Aoki]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

九州旅客鉄道の線路名称。熊本―大分間148.0キロメートル、全線単線。大分―下郡信号場(しもごおりしんごうじょう)間2.2キロメートルが交流電化。九州横断鉄道の一つ。熊本平野より白川の河谷沿いにさかのぼり、阿蘇(あそ)山の火口原を横断、阿蘇外輪山の分水嶺(ぶんすいれい)を越えて大野川流域に入り、竹田盆地を経て大分平野に達する。このため阿蘇高原線の愛称がある。大分側より犬飼(いぬかい)軽便線（1922年より犬飼線）、熊本側より宮地(みやじ)軽便線（1922年より宮地線）の名称で建設を進め、前者は1914～1925年（大正3～14）大分―玉来(たまらい)間を、後者は1914～1918年熊本―宮地間を開業したが、1928年（昭和3）玉来―宮地間の開業により両線が結ばれ、統合されて豊肥本線となった。阿蘇外輪山を越える部分に33‰（パーミル）の急勾配(こうばい)区間があり、火口原を横断する区間の景観は雄大である。1987年（昭和62）、日本国有鉄道の分割民営化に伴い、九州旅客鉄道に所属。

［青木栄一・青木　亮］

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