Tokyo Metro Yūrakuchō Line

The Tokyo Metro Yurakucho Line (東京メトロ有楽町線) is a subway line in Japan owned and operated by Tokyo Metro. The line connects Wakōshi Station in Wakō, Saitama and Shin-Kiba Station in Kōtō, Tokyo. On maps, diagrams and signboards, the line is shown using the color "gold", and its stations are given numbers using the letter "Y".

The line was named after the Yūrakuchō business district in Chiyoda, Tokyo. The proper name as given in an annual report of the Ministry of Land, Infrastructure and Transport is Line No. 8 Yūrakuchō Line (8号線有楽町線). According to the Tokyo urban transportation plan, however, it is more complicated. The line number assigned to the section south from Kotake-Mukaihara to Shin-Kiba is Line 8, but that north of Kotake-Mukaihara to Wakōshi is Line 13, which indicates the section is a portion of Fukutoshin Line which shares the same number.

Services
The Yurakucho Line runs generally northwest to southeast between Wakōshi Station in Saitama Prefecture and Shin-Kiba Station in Kōtō Ward. Although it was originally planned as a bypass for the established Marunouchi Line through central Tokyo, it was also built to serve the developing wards of Itabashi, Nerima, Toshima, and Koto. The section between Wakōshi and Kotake-mukaihara shares tracks with its sister line, the Tokyo Metro Fukutoshin Line.

The Yurakucho Line has inter-running counterparts on its northern side, both of which are "major" Japanese private railway companies in Greater Tokyo. One is the Tobu Railway at Wakōshi, north to Shinrin-kōen. The other is the Seibu Railway at Kotake-Mukaihara with its bypass line Seibu Yūrakuchō Line connecting to its main Ikebukuro Line, through trains north to Kotesashi or Hannō.

According to the Tokyo Metropolitan Bureau of Transportation, as of June 2009 the Yurakucho Line is the fifth most crowded subway line in Tokyo, at its peak running at 173% capacity between Higashi-Ikebukuro and Gokokuji stations.

Semi-express (準急) services ran on the Yurakucho Line between June 14, 2008 and March 6, 2010, operating twice hourly between Wakōshi and Shin-Kiba. Between Wakōshi and Ikebukuro, semi-express trains stopped only at Kotake-Mukaihara; between Ikebukuro and Shin-Kiba, trains stopped at all stations. The semi-express trains ran between rush hours during weekdays and more frequently on weekends and holidays. These services were abolished and replaced with local services on March 6, 2010.

Station list

 * All stations are located in Tokyo.
 * Local trains stop at every station.
 * S-Train services stop at the stations indicated by "●" and "↑" (alighting only during the morning, boarding only during the evening) and pass all stations indicated by "|".

Rolling stock
All types are operated as 10-car sets.

Tokyo Metro

 * Tokyo Metro 10000 series (from September 2006)
 * Tokyo Metro 17000 series (from 21 February 2021)

Other operators

 * Seibu 6000 and 6050 series (Not all sets are permitted to run on Yūrakuchō Line tracks)
 * Seibu 40000 series (S-Train services)
 * Seibu 40050 series
 * Tobu 9000 series
 * Tobu 9050 series
 * Tobu 50070 series
 * Tokyu 5050-4000 series could run on the line, but only in the special case of emergency schedule adjustments.

Former rolling stock

 * Tokyo Metro 7000 series (from 1974 until 29 October 2021)
 * Tokyo Metro 07 series (from 1992 until 2007)
 * Odakyu 60000 series MSE (Romancecar, as Limited Express Bay Resort, occasionally)

Depots

 * Wakō Depot (和光検車区) (main depot)
 * Shin-Kiba Depot (新木場検車区) (responsible for minor inspections; for major ones, EMUs are forwarded to the Ayase Depot (綾瀬車両基地) on the Chiyoda Line via underground connecting tracks)
 * Shin-Kiba Car Renewal (新木場CR) (specializes in railcar refurbishment: also used for Chiyoda and Hanzōmon Line railcars)

History
The Yurakucho line was originally proposed in 1962 along with the Chiyoda Line, it was originally envisioned to run between Nakamurabashi Station and Kinshicho Station. In 1968, it was later revised to run between Chikatetsu-narimasu Station in the northwest and Shintomichō Station in the southeast; the extensions to Wakoshi and Shin-kiba were not confirmed at the time.

Line 8 was planned to serve areas that were not served by the Tokyo subway network such as Nerima and Koto Wards, while providing an adequate bypass for the overcrowding Marunouchi Line from Ikebukuro to Ginza-itchōme. This initial section began construction in 1970 and opened on 30 October 1974 as the Yūrakuchō Line. In the late 1970s, the extensions towards Wakoshi and Shin-kiba were authorized. On 27 March 1980, the second section between Ginza-itchōme and Shintomichō section opened, while the third section between Eidan-narimasu (present Chikatetsu-narimasu) and Ikebukuro opened on 24 June 1983.

Through services with the Seibu Railway Seibu Yūrakuchō Line began on 1 October 1983 with the opening of the Kotake-Mukaihara – Shin-Sakuradai section. The northwestern extension to Wakōshi opened on 25 August 1987, allowing through service with the Tōbu Tōjō Line. The final section from Shintomichō to Shin-kiba opened on 8 June 1988, completing the current line.

On 18 March 1993, 07 series EMUs introduced. On 7 December 1994, the "Yūrakuchō New Line" (now the Fukutoshin Line) opened from Kotake-Mukaihara to Ikebukuro. All trains on it made Ikebukuro their terminus and did not stop at Senkawa nor Kanamechō. Through service from Shin-Kiba or Ikebukuro (on the New Line) to Nerima on Seibu Yūrakuchō Line began on that same day, with through operation to the Seibu Ikebukuro Line beyond Nerima beginning on 26 March 1998.

On 1 April 2004, the owner of the line changed from Teito Rapid Transit Authority (TRTA, Eidan) to Tokyo Metro due to the former's privatization. Women-only cars were introduced on 31 October 2005. 10000 series were introduced to the line on 1 September 2006.

On 3 May 2008, Limited Express "Bay Resort" (operated first from/to Odakyu Line) began operating. On 14 June 2008, the Tokyo Metro Fukutoshin Line began service, and the Yurakuchō New Line annexed by the Fukutoshin Line. Yurakuchō Line shares tracks with Fukutoshin Line between Wakōshi and Kotake-Mukaihara. Semi-Express service began running until they were abolished on 6 March 2010.

On October 2008, Automatic train control was enabled on the Yurakuchō Line. On 10 September 2012, 10-car 5050-4000 series sets entered revenue service on the Yurakucho Line, with inter-running through to the Tobu Tojo Line. Since March 26, 2017, Seibu operates the S-Train limited-stop express service between Toyosu and Tokorozawa on the Seibu Ikebukuro Line on weekday mornings and evenings.

On 6 August 2022, "Wanman" one-person operation began on the section between Kotake-Mukaihara and Shin-Kiba

Future developments
In 2021, plans were announced to branch the Yurakucho line at Toyosu Station, traveling north for 5.2 km connecting with Toyocho on the Tozai Line and Sumiyoshi Station on the Shinjuku Line and Hanzomon Line. An additional two stations (Edagawa and Sengoku) would also be added in the Koto Ward serving the Sengoku and Toyo districts. Tentative names for the new stations were determined in August 2022. The branch line (nicknamed the Toyozumi Line according to official city documents) is intended to aid in redevelopment efforts in Koto Ward. As of 28 January 2022 the expected cost of construction is ¥269 billion (2021). There are also plans for a spur branching off from the planned Tokyo Rinkai Subway line at Kachidoki to link up to the future Toyozumi Line (Yurakucho Line branch) platforms at Toyosu Station. The branch line is expected to be in service in the mid-2030s.

A branch line from Toyosu Station has been planned since the early 1980s, heading north via Kameari Station (on the Jōban Line) to Noda in northwest Chiba Prefecture.