The Tobu Isesaki Line (伊勢崎線) is a railway line of Tobu Railway (東武鉄道). It runs from Asakusa Station in Taito, Tokyo, through Tobu-Dobutsu-Koen Station in Miyashiro town, Saitama, to Isesaki Station in Isesaki, Gunma.
History
The line began on 27 August 1899, when the section from Kitasenju to Kuki opened. The first trains carried passengers and freight together. The company was in financial trouble and paid no dividends. After Nezu Kaichiro became president in 1905, a bridge was built over the Tone River. The line reached Ashikaga-machi (now Ashikaga-shi) on 27 August 1907. In 1902 the line was extended to Azumabashi (now Tokyo Skytree station). In 1904 a Kameido line let trains reach Ryogoku station on the Sobu Railway (総武鉄道). The full line to Isesaki opened on 13 July 1910.
In 1907 the government took over the Sobu Railway, so Tobu needed its own terminal in central Tokyo. Tobu reopened the Azumabashi to Kuki section as a freight line in March 1908. It reopened to passengers on 27 March 1910. Azumabashi station was renamed Asakusa on 1 March 1910. In the Taisho period the line was doubled and electrified in stages. The Kanegafuchi to Asakusa section was doubled in 1912, and the whole Tokyo section in 1920. The Asakusa to Nishi-Arai section was electrified in 1924, and Tobu's first electric car, the DEHA 1 type, was built for it. The Arakawa floodway works changed the route between Kanegafuchi and Nishi-Arai in 1923. Electrification reached Kasukabe to Kuki in December 1926. The whole line was electric by 1 October 1927.
From the Showa period, Tobu competed with Keisei Electric Railway (京成電気軌道) to enter Asakusa, a commercial district of Tokyo. Keisei effectively gave up, and on 25 May 1931 Tobu's line reached Asakusa Raikomon station. The station was renamed Asakusa on 1 October 1945. Several stations closed in 1943 and 1945.
After the postwar rebuilding, city functions gathered at the Yamanote Line (山手線) terminal stations. Tobu's line did not connect with the Yamanote Line, so its development fell behind. Around 1955 Tobu asked the Ministry of Transport several times for an underground line from Kitasenju toward Shimbashi or Tokyo Yaesu, but every request was refused. Instead, through running with the Eidan Hibiya Line (営団日比谷線, now Tokyo Metro Hibiya Line) began on 31 May 1962. The through service was extended to Higashi-Ginza in 1963, to Nakameguro in 1964, and to Kita-Kasukabe in 1966. Housing estates such as Soka-Matsubara opened soon after.
Rush-hour crowding grew as housing development continued. Eight-car trains began running on the surface tracks on 18 December 1972. Asakusa station's limits ruled out longer trains, so Tobu built a quadruple track between Kitasenju and Takenotsuka. It opened on 2 July 1974 and was the first quadruple track of a private railway in the Kanto region. On 16 March 1981 Sugito station was renamed Tobu-Dobutsu-Koen station, and the Hibiya Line through trains were extended to it. On 26 August 1986 ten-car trains began running in the morning rush hour between Kuki and Tobu-Dobutsu-Koen.
In 1988 and 1990 Tobu introduced detour tickets (う回乗車), so passengers could avoid changing at Kitasenju. One detour ran via Asakusa and the other via Oshiage. The detour schemes ended on 31 March 1997. In 1997 the quadruple track between Soka and Koshigaya was completed, on 25 March, and Kitasenju station was rebuilt on several levels. In 2001 the quadruple track was extended to Kita-Koshigaya, a total of 18.9 km, which made it the longest quadruple track of any private railway. On 19 March 2003 Oshiage station opened, and trains began running through to the Tokyo Metro Hanzomon Line (東京メトロ半蔵門線) and the Tokyu Den-en-toshi Line (東急田園都市線).
On 11 March 2011 the Great East Japan Earthquake stopped all trains on the line, including through services. Services resumed in stages, and through running with the Hanzomon and Tokyu lines restarted on 2 April 2011. On 17 March 2012 Gyohanbashi station was renamed Tokyo Skytree station, and station numbering was introduced on all lines. In 2020 the TH Liner (THライナー) began on 6 June as the first limited-express-type train on Hibiya Line through services. All ordinary trains became 20 m four-door cars, and platform doors were installed, starting at Kita-Koshigaya. In January 2021 some last trains were cancelled during the new coronavirus state of emergency. Platform doors were completed between Kitasenju and Kita-Koshigaya in 2025. Level crossings in the Tokyo section were removed in 2022 and 2025. On 14 March 2026 one-man operation began on ordinary trains between Kitasenju and Kita-Koshigaya.
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Written by an AI from the line's history on Japanese Wikipedia, nothing else, and checked by a program for dates and numbers that are not in those facts. It can still be wrong. Adapted from Japanese Wikipedia, CC BY-SA 4.0; this text is shared under the same licence.