Sōya Main Line

One Sōya limited express service operates each way between Sapporo and Wakkanai daily, and two Sarobetsu limited express services also operate each way between Asahikawa and Wakkanai daily.

All-stations "Local" train services operate between Asahikawa and Nayoro, at approximately 1 to 2 hour intervals. All-stations "Local" train services operate between Nayoro and Wakkanai, at approximately 3 to 4 hour intervals. Four Rapid Nayoro services operate between Nayoro and Asahikawa in each direction daily.

L: Limited Express ( Sōya / Sarobetsu )

R: All Rapid Nayoro services

r: Some Rapid Nayoro services

-: Some local trains skip marked stations

Northern extremity: W80 Wakkanai

The line was originally built as part of a link between mainland Japan and the then Japanese northern frontier of Karafuto (southern half of Sakhalin Island). From Wakkanai Port, a ferry to then Ōdomari (present Korsakov) operated until the end of World War II.

The first segment of the line from Asahigawa (present Asahikawa) to Nagayama was built by the Hokkaido Government Railway in 1898. The line was extended to Nayoro in 1903, and to Wakkanai in 1922 along the route of the later Tempoku Line (天北線, Tenpoku-sen) via Hamatombetsu. The present route via Horonobe was opened as part of the Teshio Line (天塩線, Teshio-sen).

After Japan's defeat in the war, the line lost its function as a link to Sakhalin, but remained important as a trunk line into the northern part of Hokkaido. The Sōya Main Line gradually lost all of its branch lines, and presently constitutes a long branch from the Hakodate Main Line.

Former connecting lines

Train on the Nayoro Main line, March 1973

Bridge from the former Monbetsu to Motoyama line

Bridge built on the Former Shinmei Line[3]

• Shibetsu station - A 762mm (2'6") gauge line was constructed between 1920 and 1925 along the Teshio River valley to transport forestry products, extending 21.4 km to 'Upper' Shibetsu, where it connected to the Shibetsu Forest Railway. Initially horse drawn, a steam locomotive was introduced in 1928. The line closed in 1959.
• Nayoro station - A 138 km line known as the Nayoro Main Line was built from Nayoro to Engaru on the Sekihoku Main Line between 1915 and 1921, operating until 1989. There were four lines connecting to the Nayoro Main line:
  • The 20 km Kohin'nan line from Okoppe to Om, operated from 1935 to 1985. Some construction work on a proposed extension to Kitami Esashi (see below) was undertaken before the proposal was abandoned.
  • The 34 km line from Shokotsu to Kitami Takinoue, opened 1923 and closed 1985.
  • The 28 km 762mm gauge line from Monbetsu to Motoyama, which operated from 1943 to 1973
  • The 6 km 762mm gauge line from Yubetsu to Saromako, which operated from 1930 to 1939
• Nayoro was also the junction for the Shinmei Line to Fukagawa on the Hakodate Main Line, which reached the Soya line in 1941, closing in 1995. A 51.2 km line was proposed from Shumarinai on that line to Chikubetsu on the Haboro Line (see below) with construction commencing in 1959. A substantial steel truss bridge was constructed before work was abandoned in 1962.
• Bifuka station - A 21 km 762mm gauge line was built to Niupu in 1935. In 1960 it was decided to replace the line with a 1067mm gauge line and extend it 58 km to Kitami Esashi, the terminus of a line from Hamatonbetsu on the Tempoku line (see below). The 762mm gauge line closed in 1963 and the 1067mm line opened in 1964. Substantial construction of the line to Kitami Esashi continued until abandoned in 1979, after 13.3 Billion Yen had been expended. The Bifuka - Niupu section closed in 1985.
• Otoineppu station - The Tempoku line was constructed north commencing in 1914, reaching Minami-Wakkanai in 1922. It closed in 1989. This line had the Hamatonbetsu - Kitami Esashi branch line operating from 1936 until 1985. The Utanobori Municipal Tramway was a network of 762mm gauge lines, with a 16.2 km line from Shotonbetsu to Kitami Esashi and 2 branch lines, each 10 km long. It operated 1929–70, being horse drawn until 1933.
• Toyotomi station - The Nisso Coal Co. operated an 18 km line to Sanko from 1940/45 until the mine closed in 1972.
• Toikanbetsu station - The Horonobe Municipal Tramway was a 16 km 762mm gauge line to Kamitoikan, which operated 1930–71. It was extended 4 km to a coal mine in 1941, at which time a steam locomotive was introduced. The coal mine and extension closed in 1958.
• Horonobe station - The initial northern section of the Haboro Line opened in 1935. The initial southern section from Rumoi opened in 1927, and the sections were linked in 1958. The line closed in 1987.

• List of railway lines in Japan