Muroran Main Line (室蘭本線): History & Facts

History

The line originated as a coal railway. On 1 August 1892 the Hokkaido Colliery and Railway Company opened the line from Muroran (the site of the present Higashi-Muroran) to Iwamizawa, linking the coal mines of the Iwamizawa-Asahikawa region with Muroran Port. In 1897 the line was extended to the present Muroran. The Japanese government nationalised the Hokkaido Colliery Railway under the Railway Nationalisation Act on 1 October 1906, and the line between the second Muroran Station and Iwamizawa was formally named the Muroran Main Line on 12 October 1909. The Higashi-Muroran-Muroran section was double-tracked in 1910.

The section between Oshamambe and Higashi-Muroran was opened between 1923 and 1928 as the Osawa Line (Osawa-sen, also read Choorin-sen) by the Imperial Japanese Government Railways, which later became the Japanese National Railways (JNR). It was built to bypass the mountainous section of the Hakodate Main Line and to link the inland Iburi region to Muroran Port; the name derived from its termini, Oshamambe and Wanishi (the former name of Higashi-Muroran). The Oshamambe-Shizukari segment opened first on 10 December 1923, and the through route was completed on 10 September 1928. In 1931 the two lines were merged: the Oshamambe-Iwamizawa route became the main line and the Higashi-Muroran-Muroran route the branch, the whole being renamed the Muroran Main Line. In the mid-1930s Hokkaido's first gasoline rail-car service began on the Muroran-Higashi-Muroran section.

Initially the line functioned mainly as a freight artery for coal. Growing coal traffic led to the staged double-tracking of the Higashi-Muroran-Mikawa section between 1920 and 1958. Between 1964 and 1975 the 42 km Oshamambe-Toya section was also double-tracked, with realignments that shortened the route by 1.7 km. As coal mining declined, the line's principal traffic shifted to passengers from the 1960s. The last regular steam-hauled passenger service in Japanese National Railways operation ran between the second Muroran Station and Iwamizawa on 14 December 1975, hauled by locomotive C57 135. The Numanohata-Muroran section, 74.9 km, was electrified at 20,000 V AC 50 Hz on 1 October 1980 in conjunction with the electrification of the Chitose Line towards Sapporo.

JNR KiHa 40-1700 series DMU on the Muroran Main Line between Kuriyama and Kurioka.Tennen-Gas · CC BY-SA 3.0 · Wikimedia Commons

On 1 April 1987, with the privatisation of JNR, JR Hokkaido took over the whole line as the primary railway operator, while the Japan Freight Railway Company (JR Freight) became the secondary operator over the Oshamambe-Iwamizawa section. The Oshamambe-Numanohata portion forms part of the main link route between Sapporo and Hakodate; the limited express Hokuto runs along it, together with the Suzuran between Sapporo and Muroran. Local services are operated with diesel multiple units such as the KiHa 40 and KiHa 150, and 737 series electric multiple units were introduced on the electrified Tomakomai-Muroran section. The maximum speed is 120 km/h between Oshamambe and Numanohata.

The 28.736 km stretch between Shiraoi and Numanohata is the longest straight railway section in Japan, although turnout-associated curves and similar features mean the track is not necessarily straight throughout. On 31 March 1947 two trains collided head-on inside a tunnel near Shizukari, killing four people and injuring 41. In 2000 the eruption of Mount Usu closed the Higashi-Muroran-Oshamambe section; services were restored in stages, and full normal operation resumed on 8 June 2000. On 18 November 2016 JR Hokkaido announced plans to rationalise up to 1,237 km, roughly half of its network, naming the sections it could not maintain on its own. For this line's Numanohata-Iwamizawa section, the company proposed talks with local governments on measures such as cost cutting, fare increases, promoting use and separating track ownership from train operation.

Stations on this line

47 stations tracked on the map, listed alphabetically. Select any to read its page.

Timeline

18921 August: the Hokkaido Colliery and Railway Company opens the line from Muroran (now Higashi-Muroran) to Iwamizawa to link coal mines to Muroran Port.
1897The line is extended to the present Muroran Station.
19061 October: the Hokkaido Colliery Railway is nationalised; the second Muroran-Iwamizawa section becomes a government line.
190912 October: the second Muroran-Iwamizawa section is officially named the Muroran Main Line.
191027 December: the Higashi-Muroran (then Wanishi)-Muroran section is double-tracked.
192310 December: the Oshamambe-Shizukari segment of the government Osawa Line opens, the first part of the Oshamambe-Higashi-Muroran route.
192810 September: the through route is completed; the Osawa Line bypasses the mountainous section of the Hakodate Main Line and links inland Iburi to Muroran Port.
19311 April: the Osawa Line is merged in; Oshamambe-Iwamizawa becomes the main line and Higashi-Muroran-Muroran the branch, renamed the Muroran Main Line.
1934/1935Hokkaido's first gasoline rail-car service begins on the Muroran-Higashi-Muroran section. The year is given as 1934 or 1935.
194731 March: two trains collide head-on inside a tunnel near Shizukari, killing four and injuring 41.
1958The Higashi-Muroran-Mikawa section completes its staged double-tracking that began in 1920.
197514 December: the last regular JNR steam-hauled passenger service runs between Muroran and Iwamizawa, hauled by C57 135. The 42 km Oshamambe-Toya double-tracking (begun 1964, with realignments shortening the route by 1.7 km) concludes.
19801 October: the 74.9 km Numanohata-Muroran section is electrified at 20 kV AC 50 Hz, with the Chitose Line.
19871 April: on JNR privatisation JR Hokkaido becomes primary operator of the whole line; JR Freight becomes secondary operator over Oshamambe-Iwamizawa.
2000The eruption of Mount Usu closes the Higashi-Muroran-Oshamambe section; full normal operation resumes on 8 June.
201618 November: JR Hokkaido announces plans to rationalise up to 1,237 km (~50% of the network), naming the Numanohata-Iwamizawa section among those it cannot maintain alone and proposing talks with local governments on measures such as separating track ownership from train operation.