Tokyo Metro Tozai Line
The Tokyo Metro Tōzai Line is a rapid transit line in Tokyo and Chiba Prefecture, Japan, owned and operated by Tokyo Metro. The line runs between Nakano in Nakano-ku, Tokyo and Nishi-Funabashi in Funabashi, Chiba Prefecture.
The Tōzai Line was referred to as Line 5 during the planning stages; the seldom-used official name is Line 5 Tōzai Line.
In 2024, the line carried a daily average of nearly 1.5 million passengers, making it the busiest line on the Tokyo subway network. On maps, diagrams and signboards, the Tōzai Line is shown using the color "sky blue" and its stations are given numbers using the letter "T".
Overview
The line runs through central Tokyo from east to west via Takadanobaba, Waseda, Ōtemachi, Nihombashi, Kiba and Urayasu. It was opened as a bypass route for the Chuo Rapid Line and the Sobu Line, which were heavily congested at the time. It is the only Tokyo Metro line to extend into Chiba Prefecture It also runs above-ground for from to, nearly half of the line and longer than any other railway line in the Tokyo subway network.The Tōzai Line features through services at both ends of the line. Trains run onto the JR East Chūō-Sōbu Line for at the western end, and onto either the Chūō-Sōbu Line for or the Tōyō Rapid Railway Line for at the eastern end.
According to the Tokyo Metropolitan Bureau of Transportation in 2018, the Tokyo Metro Tōzai Line continues to be most crowded subway line in Tokyo, and the most crowded train line in all of Japan, with its peak running at 199% capacity between and stations. Women-only cars were introduced on the line for use during morning rush hour on November 20, 2006.
During the COVID-19 pandemic, peak ridership dropped from a rate of 199% in 2019 to 123% in 2020.
History
Early years
The original plan for what is now the Tōzai Line was included in a report by the Tokyo City and Area Transportation Research Committee, which was established within the Ministry of Home Affairs in 1917. The proposal outlined a route connecting “Ikebukuro – Takadanobaba – Iidabashi – Otemachi – Susaki”.In 1920, a construction patent for this route was granted to the Tokyo Railway. However, following the Great Kantō Earthquake of 1923, the patent was revoked along with those for other planned lines because construction had not yet commenced.
The route license for the Tōzai Line originates from the six municipal subway lines planned by Tokyo City, the predecessor of today’s Tokyo special wards, prior to World War II. The license was granted on May 16, 1925, under Ministry of Home Affairs Notification No. 56 of 1925.
The present Tōzai Line corresponds to the former Line 5, which was authorized as a 14.2-kilometer route running from “Ikebukuro – Waseda – Iidamachi – Hitotsubashi – Tokyo – Eitaibashi – Susaki”. As part of the initial phase of the Tokyo Municipal Subway project, Tokyo City planned to begin construction on Line 3 between Shibuya and Sugamo and on Line 5 between Ikebukuro and Susaki. However, due to the city’s substantial public debt and concerns over deteriorating finances, the Ministry of Home Affairs and the Ministry of Finance opposed the project, and construction approval was not granted.
Following this setback, no further construction plans were pursued, and the Teito Rapid Transit Authority, commonly known as the Eidan Subway, was subsequently established. In 1941, all subway route licenses held by the Tokyo municipal government were transferred to the Teito Rapid Transit Authority in exchange for compensation.
By contrast, the section corresponding to the present-day Tōyōchō to Nishi-Funabashi segment was originally licensed to the Tokyo Narishiba Electric Railway prior to World War II. The application was approved in 1927, with the eastern terminus Tōyōchō designated as Higashi-hirai. However, this license ultimately expired in 1940 after construction failed to proceed.
Post-war construction
The Tōzai Line was planned by a review committee of the then Ministry of Transportation in 1962 and numbered Line 5. Its name literally means "East-West Line", and it was primarily planned to relieve traffic on the busy Sōbu Main Line as well as provide a straight crosstown connection through north-central Tokyo. Although this corridor is also served by the Tokyo Metropolitan Bureau of Transportation Shinjuku Line and JR Keiyō Line, the Tōzai Line continues to operate beyond capacity due to its accessibility to other lines, as well as to growing condominium developments in eastern Tokyo.The to section opened in 1964, and the remainder opened in stages until its completion in 1969. Through service with the then Japanese National Railways – a first for a Tokyo subway line – began in 1969 connecting the Chūō and Sōbu lines. This is a rare situation in Tokyo, as the only other subway line with through services onto JR lines is the Chiyoda Line.
Due to a surge in ridership on the Tōzai Line, the Teito Rapid Transit Authority introduced 12 new-build 5000 series cars and transferred 50 from the Chiyoda Line in 1981 in an effort to increase capacity on the line. Rapid residential development in the Urayasu and Kasai areas further increased demand. In response, TRTA introduced rapid trains that ran non-stop between and stations, and stopped at every station west of, in November 1986.
The Tōyō Rapid Railway Line, effectively an eastward extension of the line, opened in 1996. It nevertheless remains a private entity to which the Tōzai lines offers through services.
Chronology
- March 16, 1966: The line is extended at both ends. It now runs between Nakano and Takebashi.
- April 28, 1966: Through service to the Chūō Line of JNR commences as far as Ogikubo.
- October 1, 1966: Takebashi to Ōtemachi section opens.
- September 14, 1967: Ōtemachi to Tōyōchō section opens.
- March 29, 1969: Tōyōchō to Nishi-Funabashi section opens and Rapid service begins.
- April 8, 1969: Through service on the Chūō Line is extended to Mitaka, and through service begins on the Sōbu line to Tsudanuma.
- April 8, 1972: Through service on the Sōbu Line is withdrawn except during rush hours.
- 1975: Another type of Rapid service is introduced, calling at Urayasu between Tōyōchō and Nishi-Funabashi.
- October 1, 1979: Nishi-Kasai station opens.
- March 27, 1981: Minami-Gyōtoku station opens.
- 1986: Commuter Rapid service is introduced, running non-stop between Urayasu and Nishi-Funabashi.
- 1996: The Rapid service that runs non-stop between Tōyōchō and Nishi-Funabashi ceases.
- April 27, 1996: Tōyō Rapid Line opens between Nishi-Funabashi and Tōyō-Katsutadai. Through service begins.
- January 22, 2000: Myōden station opens.
- April 1, 2004: Teito Rapid Transit Authority becomes Tokyo Metro.
- November 20, 2006: Women-only cars are introduced during morning rush hours.
Services
Through services to via the JR East Chūō Line and via the Tōyō Rapid Railway run all day. Outside of rush hours, only local trains run through to the Chūō Line and only rapid trains run through to the Tōyō Rapid Railway. During the morning and evening peak periods, through services run to via the JR East Sōbu Line.
Station list
- Local trains stop at every station. Rapid trains stop at stations marked "●" and do not stop at those marked "｜". Some weekday westbound trains do not stop at stations marked "↑".
Rolling stock
Present
Tōzai Line trains are 10-car formations of -long cars, with four doors per side and longitudinal seating. The maximum operating speed is. Newer trains feature wide doors to allow for faster boarding times.- Tokyo Metro
- *05/05N series
- *07 series
- *15000 series
- Tōyō Rapid Railway
- *2000 series
- East Japan Railway Company
- *E231-800 series
Past
- Tokyo Metro
- *5000 series
- *8000 series
- JR East
- *301 series
- *103-1000 series
- *103-1200 series
- Tōyō Rapid
- *1000 series
Depots
- Fukagawa Depot
- Gyōtoku Depot
- Fukagawa Workshop