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Dosan Line

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Dosan Line
Nanpū 2000 series DMU at Sanuki-Saida Station
Overview
StatusIn operation
OwnerThe logo of Shikoku Railway Company (JR Shikoku). JR Shikoku
LocaleKagawa, Tokushima, Kōchi Prefectures
Termini
Stations61
Service
TypeHeavy rail
History
Opened23 May 1889; 135 years ago (1889-05-23)
Completed12 November 1951; 72 years ago (1951-11-12)
Technical
Line length198.7 km (123.5 mi)
Number of tracks1
CharacterRural
Track gauge1,067 mm (3 ft 6 in)
Minimum radius200 m (660 ft)
Electrification1,500 V DC overhead catenary (Tadotsu - Kotohira)
Operating speed120 km/h (75 mph)
Route map
Dosan Line
Dosan line train pulling into Zentsūji Station, 2021

Dosan Line (土讃線, Dosan-sen) is a railway line in Shikoku, Japan, operated by the Shikoku Railway Company (JR Shikoku). It connects Tadotsu Station in Tadotsu, Kagawa, and Kubokawa Station in Shimanto, Kōchi. The line links the city of Kōchi with northern Shikoku and the island of Honshū via the Seto-Ōhashi Line. The first section of the line between Tadotsu and Kotohira opened in 1889, Kochi was connected to the northern section of the line in 1935, and the western extension of the line was completed in 1951. The name of the line comes from "Tosa" () and "Sanuki" (), the old provincial names of present-day Kōchi Prefecture and Kagawa Prefecture, respectively.

History

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The first section opened, between Tadotsu and Kotohira, was constructed by the Sanuki Railway Co. in 1889. The company was nationalised in 1906.

The Kotohira - Awa Ikeda section was opened in 1914 and connected to the Tokushima line.

The Susaki - Kochi - Kusaka section opened in 1924, and was extended north in sections 1925-35, where it connected to the northern section at Minawa, the line from Awa Ikeda having been extended there in 1931.

The Susaki - Tosakume section opened 1939, with extensions to Kageno opening 1947 and to Kubakawa in 1951.

CTC signalling was commissioned between Tadotsu - Kochi in 1967, and the 4,180m Oboke tunnel and associated realignment opened the following year.

The 2,583m Osugi tunnel and associated realignment opened in 1973. CTC signalling was extended to Kubokawa in 1986, and the Tadotsu - Kotohira section was electrified the following year prior to the privatization of JNR. However, the maximum speed of electric trains in this section is limited to 85 km/h due to the overhead catenary being a direct-line suspension system (similar to trams) as a result of a lack of funds during construction at the end of the JNR era. On the other hand, the diesel-powered limited express JR Shikoku 2000 series is able to run at 120 km/h, while regular diesel trains can run at 95 km/h. As such, the diesel trains operating in this section is able to run faster than electric trains. To reduce the burden on the overhead catenary, electric trains operate with only one raised pantograph in addition to the speed limit. The overhead catenary of platform 1 at Kotohira Station is the only section along the entire line to have a Simple Catenary System typically used on electrified JR lines.

After the privatization of JNR, there was a plan to electrify the Dosan Line to Awa-Ikeda along with the Yosan Line, but the former did not come to fruition. The reasoning being the low return on investments due to the sharp decline in traffic south of Kotohira, and the many narrow tunnels making the installation of overhead wires difficult. As such, it was decided that a more rational plan was to introduce new high-speed diesel trains for limited express operations as opposed to electrification. In a 2006 submission to the subcommittees of the Ministry of Land, Infrastructure, Transport and Tourism, JR Shikoku cited the electrification of the Kotohira - Kochi section as one of the desired long-term investments.

Freight trains ceased operating between Tadotsu - Kochi in 2005.

Former connecting lines

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  • Kotohira station - The Kotohira Express Railway Co. operated a 16 km line to Sakaide on the Yosan Line 1930-44, with the line formally closing in 1954.
  • Tadotsu station - The Kotohira Sangu Railway Co. operated a 27 km line to Sakaide 1922/28 - 1963, with a 7 km branch to Kotohira operated 1923-63.

Services

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Rapid Sunport 7000 series EMU

Nanpū (南風) limited express trains make 14 round-trips per day between Okayama and Kōchi, Nakamura, or Sukumo. Shimanto (しまんと) limited expresses make five round trips per day between Takamatsu and Kōchi, Nakamura, or Sukumo. The Sunport (サンポート) rapid service trains link Kotohira and Takamatsu once an hour.

The line is generally divided into three parts for local services at Awa-Ikeda and Kōchi. For the segment between Tadotsu and Kotohira, there are through services to/from Okayama and Takamatsu. The Tosa Kuroshio Railway Gomen-Nahari Line has through service to/from Kōchi.

Stations

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  • Local trains generally stop at all stations, but sometimes skip stations marked "▽".
  • Sunport (Takamatsu - Tadotsu - Kotohira) rapid trains stop at all stations on the Dosan Line.
  • See the articles on the Nanpū and Shimanto limited express services for details of station stops.
  • Trains are able to pass each other at stations marked "◇" and "◆" (switchback); trains cannot pass at stations marked "|".
Station No. Station name Japanese Distance (km) Transfers   Location
Between
stations
Total
Through service to/from the Yosan Line and the Seto-Ōhashi Line
D12 Tadotsu 多度津 - 0.0      Yosan Line (Y12) (some trains through to Utazu) Tadotsu, Nakatado District Kagawa
D13 Konzōji 金蔵寺 3.7 3.7   Zentsūji
D14 Zentsūji 善通寺 2.3 6.0  
D15 Kotohira 琴平 5.3 11.3 Kotoden Kotohira Line (Kotoden-Kotohira)
Electrified section ends at this station
Kotohira, Nakatado District
D16 Shioiri 塩入 6.4 17.7   Mannō, Nakatado District
D17 Kurokawa 黒川 3.9 21.6  
D18 Sanuki-Saida 讃岐財田 2.3 23.9   Mitoyo
D19 Tsubojiri 坪尻 8.2 32.1   Miyoshi Tokushima
D20 Hashikura 箸蔵 3.3 35.4  
D21 Tsukuda 3.4 38.8      Tokushima Line (B24)
D22 Awa-Ikeda 阿波池田 5.1 43.9      Tokushima Line (B25)
D23 Minawa 三縄 3.9 47.8  
D24 Iyaguchi 祖谷口 4.5 52.3  
D25 Awa-Kawaguchi 阿波川口 2.8 55.1  
D26 Koboke 小歩危 4.7 59.8  
D27 Ōboke 大歩危 5.7 65.5  
D28 Tosa-Iwahara 土佐岩原 7.2 72.7   Ōtoyo, Nagaoka District Kōchi
D29 Toyonaga 豊永 4.0 76.7  
D30 Ōtaguchi 大田口 3.7 80.4  
D31 Tosa-Ananai 土佐穴内 2.8 83.2  
D32 Ōsugi 大杉 4.0 87.2  
D33 Tosa-Kitagawa 土佐北川 6.1 93.3  
D34 Kakumodani 角茂谷 2.2 95.5  
D35 Shigetō 繁藤 2.1 97.6   Kami
D36 Shingai 新改 6.3 103.9  
D37 Tosa-Yamada 土佐山田 7.4 111.3  
D38 Yamada-Nishimachi 山田西町 0.8 112.1  
D39 Tosa-Nagaoka 土佐長岡 2.0 114.1   Nankoku
D40 Gomen 後免 2.1 116.2 Tosa Kuroshio Railway Gomen-Nahari Line (some trains through to Kōchi; GN40)
D41 Tosa-Ōtsu 土佐大津 3.2 119.4   Kōchi
D42 Nunoshida 布師田 2.0 121.4  
D43 Tosa-Ikku 土佐一宮 1.3 122.7  
D44 Azōno 薊野 1.8 124.5  
D45
K00
Kōchi 高知 2.1 126.6 Tosaden Sanbashi Line (Kōchi-Ekimae)
K01 Iriake 入明 1.3 127.9  
K02 Engyōjiguchi 円行寺口 0.8 128.7  
K03 Asahi 1.5 130.2 Tosaden Ino Line (Asahi-Ekimae-Dōri)
K04 Kōchi-Shōgyō-Mae 高知商業前 1.1 131.3 Tosaden Ino Line (Kagamigawabashi)
K05 Asakura 朝倉 1.4 132.7 Tosaden Ino Line (Asakura-Ekimae)
K06 Edagawa 枝川 3.5 136.2 Tosaden Ino Line (Edagawa) Ino, Agawa District
K07 Ino 伊野 1.8 138.0 Tosaden Ino Line (Ino-Ekimae)
K08 Hakawa 波川 1.5 139.5  
K08-1 Omura-Jinja-Mae 小村神社前 2.1 141.6   Hidaka, Takaoka District
K09 Kusaka 日下 2.1 143.7  
K10 Okabana 岡花 2.0 145.7  
K11 Tosa-Kamo 土佐加茂 2.9 148.6   Sakawa, Takaoka District
K12 Nishi-Sakawa 西佐川 3.8 152.4  
K13 Sakawa 佐川 1.8 154.2  
K14 Erinono 襟野々 1.8 156.0  
K15 Togano 斗賀野 2.0 158.0  
K16 Asō 吾桑 5.4 163.4   Susaki
K17 Ōnogō 多ノ郷 2.7 166.1  
K18 Ōma 大間 0.9 167.0  
K19 Susaki 須崎 1.7 168.7  
K20 Tosa-Shinjō 土佐新荘 1.9 170.6  
K21 Awa 安和 3.0 173.6  
K22 Tosa-Kure 土佐久礼 6.1 179.7   Nakatosa, Takaoka District
K23 Kageno 影野 10.7 190.4   Shimanto, Takaoka District
K24 Rokutanji 六反地 1.8 192.2  
K25 Niida 仁井田 2.0 194.2  
K26 Kubokawa 窪川 4.5 198.7 Tosa Kuroshio Railway Nakamura Line (TK26) (all JR Shikoku Yodo Line trains run through to Kubokawa)

See also

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References

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This article incorporates material from the corresponding article in the Japanese Wikipedia

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