The Uchibo Line (内房線) is a main line run by East Japan Railway Company (JR East). It runs from Soga Station in Chiba City, through Kisarazu Station in Kisarazu, to Awa-Kamogawa Station in Kamogawa, Chiba.
History
The line started on the Tokyo Bay side of Boso Peninsula as the Kisarazu Line (木更津線). On 28 March 1912 the Soga to Anegasaki section opened. On 21 August 1912 the Anegasaki to Kisarazu section opened. The line was extended in small steps. It reached Awa-Hojo station, now Tateyama station, on 24 May 1919, and at that point it was renamed the Hojo Line (北条線). On 11 July 1925 the line reached Awa-Kamogawa, which completed the section that is now the Uchibo Line. On 15 April 1929 the Boso Line reached Awa-Kamogawa, and the Hojo Line was merged into it.
On 1 April 1933 the Boso Line was split. The section from Soga to Awa-Kamogawa became the Boso West Line (房総西線). In summer 1950 a temporary train called Shiokaze (潮風) ran for swimmers, the first after the Pacific War. On 1 July 1935 diesel railcars began running between Soga and Kisarazu. On 20 November 1941 Iwane station opened. On 1 March 1946 Awa-Hojo station was renamed Tateyama station. Nagaura station opened on 10 January 1947. On 1 October 1954 almost all trains became diesel railcars, and a timetable with one-hour intervals was introduced. On 10 April 1956 Shusai station was renamed Kimitsu station.
On 1 July 1964 Soga to Hamano was doubled and given automatic signals. On 20 September 1964 Hamano to Yahatajuku was also doubled. In 1963 and 1964 summer, electric trains were brought onto the then non-electrified Boso West Line to make up for a shortage of cars. The pantographs were folded at Chiba, and diesel locomotives hauled the trains to Tateyama. On 1 February 1965 ATS-S was introduced across the whole line. Between 1966 and 1967 the stretch from Goi to Kazusa-Minato and from Kazusa-Minato to Tateyama was given automatic signals. On 13 July 1968 Chiba to Soga to Kisarazu was electrified, and a rapid service using 101 series trains of the Chuo and Sobu local lines began between Nakano and Kisarazu. On 10 July 1969 the last steam-hauled passenger train ran, a farewell run pulled by C57-105 that ended regular steam passenger trains. On 11 July 1969 Kisarazu to Chikura was electrified. On 1 July 1971 Chikura to Awa-Kamogawa was electrified. On 1 July 1972 the Tateyama to Awa-Kamogawa section was controlled by centralised traffic control (CTC). On 15 July 1972 the line was renamed the Uchibo Line (内房線), and the 183 series began the limited express Sazanami (さざなみ). On the same day the Sobu Rapid Line opened between Kinshicho and Tokyo, and trains through to it replaced the rapid services that used 101 series trains.
On 31 March 1974 Narabe station was renamed Sodegaura station. On 15 November 1982 freight service between Kisarazu and Awa-Kamogawa ended. On 14 March 1985 the Kimitsu to Tateyama section was converted to CTC. On 1 November 1986 freight service between Soga and Kisarazu ended. On 1 April 1987 the national railways were split up, and East Japan Railway Company (JR East) took over the line. On 10 March 1990 the Keiyo Line opened in full, and through trains ran from the Keiyo Line to Tokyo Station.
On 22 March 1997 smoking was banned on all local trains from Kimitsu to Awa-Kamogawa. On 4 February 2001 ATS-P began between Soga and Iwane, and on 18 March 2001 between Iwane and Kimitsu. On 18 November 2001 the Suica IC card service began between Soga and Kimitsu, which was then part of the Tokyo suburban area. On 16 October 2004 E257 500 series trains were introduced on the Sazanami. On 3 September 2006 CTC was introduced between Kisarazu and Kimitsu, and the CTC system was renewed between Kimitsu and Tateyama. The automatic route control (PRC) system was introduced between Soga and Tateyama. On 27 September 2008 ATS-P began between Kimitsu and Tateyama. On 14 March 2009 Kimitsu to Awa-Kamogawa joined the Tokyo suburban area, with Suica service. On 1 October 2009 209 series 2000 番台 and 2100 番台 trains began service.
On 10 February 2010 the CTC and PRC system between Tateyama and Awa-Kamogawa was renewed, and PRC-type automatic announcements were introduced on the Sotobo Line section. On 28 February 2010 ATS-P began between Tateyama and Awa-Kamogawa. On 27 September 2010 an imperial visit train made up of E655 series cars, including a special car, ran from Tateyama to Tokyo through the Keiyo Line. On 22 November 2012 the Yamaboshi bridge between Emi and Futomi was certified as a civil engineering heritage. On 16 October 2013 Typhoon No. 26 damaged a slope near the Minato River bridge between Kazusa-Minato and Takeoka, and service between Sanugi-machi and Hamakanaya was suspended until 19 October. On 14 March 2015 the Sazanami ran only on weekday morning up trains and night down trains. On 3 March 2017 the special rapid service between Tokyo and Tateyama ended, and on 4 March 2017 some trains were split at Kisarazu in the daytime, which reduced daytime trains between Chiba and Kisarazu. On 6 January 2018 a cycle train called B.B.BASE Uchibo, run by BOSO BICYCLE BASE, began between Ryogoku and Wadaura.
On 19 November 2020 tsunami evacuation guidance signs were installed. On 13 March 2021 E131 series trains began between Kisarazu and Awa-Kamogawa, with one-man operation and through running with the Sotobo Line between Awa-Kamogawa and Kazusa-Ichinomiya. On 11 June 2022 a charter train marked the 110th anniversary of the Soga to Anegasaki opening, running round trips between Chiba and Tateyama. On 1 July 2026 the regional branch offices were replaced by business divisions, and the whole line came under the Boso Business Division. On 13 August 2026 heavy rain across Chiba Prefecture suspended trains between Chiba and Kisarazu from the afternoon until the next day. On 6 September 2026 a landslide between Emi and Futomi closed the Chikura to Awa-Kamogawa section until 19 September, and buses ran from 9 September until 20 o'clock on 19 September. On 21 September 2026 heavy rain from Typhoon No. 25 brought earth into the line at five places between Anegasaki and Nagaura. Anegasaki to Kisarazu was suspended for at least three months. Between Chiba and Anegasaki only turn-back trains ran, and the through running to the Sobu Rapid Line stopped. A bus service planned for 28 September could not be arranged because there were not enough vehicles. On 5 October 2026 a turnback facility was built at Nagaura, and service between Nagaura and Kisarazu resumed. Buses ran between Anegasaki and Nagaura.
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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.