The Tokyu Oimachi Line (大井町線) is run by Tokyu Electric Railway (東急電鉄). It runs from Oimachi Station in Shinagawa ward, Tokyo, to Mizonokuchi Station in Takatsu ward, Kawasaki, Kanagawa.
History
The line began in 1927. On 6 July 1927 Meguro Kamata Electric Railway (目黒蒲田電鉄) opened the section from Oimachi to Ōokayama, and it was already called the Oimachi Line. On 10 October 1928 Ikezuki Station (now Kita-Senzoku) opened. On 1 November 1929 the Jiyūgaoka to Futakotamagawa section opened as the Futakotamagawa Line. On 25 December 1929 Ōokayama to Jiyūgaoka opened, which completed the whole line. The Futakotamagawa Line was merged into the Oimachi Line, and through running from Oimachi to Futakotamagawa began. On 1 April 1930 Oyamadai Station opened. On 21 May 1930 Ikezuki was renamed Senzoku-kōen. On 1 April 1933 Nakamaruyama was renamed Midorigaoka. On 1 January 1936 three stations were renamed: Togoshi became Shimo-Shinmei, Hebikubo became Togoshi-kōen, and Senzoku-kōen became Kita-Senzoku. On 1 April 1936 express trains were dropped in a timetable revision. Japanese Wikipedia says the exact date when express service started is not clear.
On 1 December 1940 Futakotamagawa Station on the Oimachi Line and Yomiuri-Yūen Station on the Tamagawa Line were merged and renamed Futakoyomiuri-en. On 1 July 1943 the Tamagawa Line section from Futakoyomiuri-en to Mizonokuchi changed gauge from 1372 mm to 1067 mm and was merged into the Oimachi Line. On 20 October 1944 Futakoyomiuri-en was renamed Futakotamagawa. On 1 October 1945 the Futakotamagawa to Mizonokuchi section changed from tramway law to the Local Railway Act. On 1 March 1951 Higashi-Senzoku moved and was renamed Hatanodai. On 1 August 1954 Futakotamagawa was renamed Futakotamagawa-en. On 15 January 1958 the overhead line voltage was raised from 600 V to 1500 V. On 11 October 1963 the Oimachi Line was renamed the Den-en-toshi Line (田園都市線), and the Oimachi name disappeared for a time. On 21 September 1964 the Hatanodai to Kita-Senzoku section was elevated. On 20 January 1966 Midorigaoka, Jiyūgaoka and Mizonokuchi were renamed with their modern spellings.
On 1 March 1976 some trains were increased from four cars to five. On 12 August 1979 Den-en-toshi Line trains began running from Futakotamagawa-en over the Shin-Tamagawa Line to Shibuya and on to the Hanzōmon Line (半蔵門線) of the Teito Rapid Transit Authority (帝都高速度交通営団). At the same time the Oimachi to Futakotamagawa-en section was split off and the Oimachi name came back, after about 16 years. Three series were used then: the Deha 3450, the first 5000 series and the 8000 series. On 1 April 1981 the first 6000 and 7200 series, in six-car sets of 18 m cars, began running, alongside the 20 m five-car sets of the first 5000 series. This ended service for the old 3000 series on the line. On 30 November 1982 freight service was ended across the whole line. On 31 March 1985 the first 5000 series ended service.
In October 1986 spare 8500 series cars shared with the Den-en-toshi and Shin-Tamagawa lines began service on this line, about a month after they were built. In November 1986 Toyoko Line set 9001F was converted to five cars and ran on this line for just under a month. In December 1986 more shared 8500 series spare cars began service. Japanese Wikipedia says these were the first new cars on the line since the Oimachi Line was formed. On 9 March 1988 set 9007F began service for this line, and for a long time it was the only new car built for the line. On 1 September 1988 the 8090 series, moved from the Toyoko Line, began service. On 26 January 1989 the 18 m six-car operation ended, and all trains became five 20 m cars.
On 6 August 2000 Futakotamagawa-en Station was renamed Futakotamagawa. On 11 March 2006 a door on an 8000 series train opened while the train was running. The Aircraft and Railway Accidents Investigation Commission (航空・鉄道事故調査委員会) investigated it as a serious incident. From 18 March 2006 express trains that ran through to the Den-en-toshi Line operated on Saturdays and holidays only. On the Oimachi Line they stopped at every station, three each way, until 22 March 2008. On 15 November 2007 trains that ended at Jiyūgaoka were abolished. On 23 February 2008 the safety system changed from Tokyu-type ATS to ATC-P. On 28 March 2008 express trains began running within the Oimachi Line, and 6000 series six-car trains began service. On 11 July 2009 the line was extended to Mizonokuchi, and two kinds of local trains, with blue and green colours, began running. In February 2012 station numbering was introduced. On 3 March 2012 platform screen doors began use at Oimachi. On 24 February 2013 the platform at Togoshi-kōen was extended by two cars, a level crossing was moved, and the practice of keeping some doors shut at that station ended.
On 4 November 2017 express trains began running as seven-car trains. On 9 February 2018 the change to seven-car express trains was completed. On 28 March 2018 the 6020 series began service. On 14 December 2018 Q Seat, a paid reserved-seat service, began on five weekday night express trains to Nagatsuda. On 1 October 2019 a timetable revision extended some express trains to Chūō-Rinkan. On 6 June 2020 the number of weekday Q Seat trains rose to ten. On 13 March 2021 a timetable revision moved the last trains earlier and adjusted the daytime service.
On 2 July 2025 the 6050 番台 cars of the 6020 series began service. On 10 October 2025 a design error in signal control was found at Futakotamagawa Station, which also serves the Den-en-toshi Line. It was repaired on 20 October. Japanese Wikipedia says one-man operation is planned to start in fiscal 2032 (令和14年度), and it ends there.
See the live map and facts in the Data view →
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.