Marunouchi Line

Marunouchi Line
Marunouchi Line
	Marunouchi Line 2000 series trains at Yotsuya Station
Overview
Other name	Line 4
Native name	丸ノ内線
Status	In service
Owner	Tokyo Metro Co., Ltd.
Line number	M/Mb
Locale	Tokyo
Termini	Ogikubo (Main) / Honancho (Branch); Ikebukuro (Main) / Nakano-sakaue (Branch);
Stations	28 (including branch line)
Color on map	Red
Service
Type	Rapid transit
System	Tokyo subway (Tokyo Metro)
Operator(s)	Tokyo Metro Co., Ltd.
Depot(s)	Koishikawa, Nakano
Rolling stock	2000 series
Daily ridership	1,159,898 (2017)
History
Opened	January 20, 1954
Last extension	1962
Technical
Line length	27.4 km (17.0 mi) (Main line); 3.2 km (2.0 mi) (Branch Line)
Number of tracks	2
Track gauge	1,435 mm (4 ft 8+1⁄2 in) standard gauge
Minimum radius	140 m (460 ft) (Main line: Near Ginza); 125 m (410 ft) (Branch Line)
Electrification	Third rail, 600 V DC
Operating speed	75 km/h (47 mph) (Main line); 65 km/h (40 mph) (Branch line)
Signalling	Tokyo Metro CS-ATC; Communications-based train control;
Maximum incline	3.5%
Route map
Route map
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	Keiō Line
	Odakyu Odawara Line
	Ōedo
	Line
	Shinjuku-
	nishiguchi
	Chūō-Sōbu Line
	Yamanote Line
	Chūō Main Line
	Saikyō, Shōnan Shinjuku lines
	Seibu Shinjuku
	of Seibu Shinjuku Line
	Chūō Main Line,
	Chūō-Sōbu Line
	Namboku, Yūrakuchō,
	Hanzōmon lines (Nagatachō)
	Namboku Line (G&N-06
	Tameike-sannō)
	Yamanote Line
	Keihin Tōhoku Line
	Tōkaidō Line
	Shinkansen
	Tōkaidō Shinkansen
	Tōhoku, Jōetsu, Nagano Shinkansen
	Tōkaidō Main Line
	Keihin-Tōhoku Line
	Yamanote Line
	Chūō Line (Rapid)
	Chūō Line (Rapid)
	Chūō–Sōbu Line
	Ōedo,
	Mita lines
	Saikyō, Shōnan-Shinjuku lines
	Yūrakuchō Line

The Marunouchi Line (丸ノ内線, Marunouchi-sen) is a subway line in Tokyo, Japan, operated by Tokyo Metro. The line runs in a U-shape between Ogikubo Station in Suginami and Ikebukuro Station in Toshima, with a branch line between Nakano-Sakaue Station and Hōnanchō Station. The official name is Line 4 Marunouchi Line (4号線丸ノ内線, Yon-gō-sen Marunouchi-sen).

The Marunouchi Line was the fourth subway line constructed in Japan, following the Osaka Municipal Subway Yotsubashi Line.

Its design is similar to that of the Ginza Line, the oldest subway line in Tokyo and in Asia. Both lines are standard gauge and use third rail power, unlike subsequent Tokyo subway lines which use overhead wires and are mostly narrow gauge to accommodate through services with other railway lines.

The line's name is derived from Marunouchi, a district in Chiyoda. It was adopted in 1953 by the Teito Rapid Transit Authority, the operator at the time. Prior to this line, a Tokyo tram line of the same name (opened in 1921) operated above ground between Tokyo and Ōtemachi, along the route of the present line.

On maps, diagrams and signboards, the line is shown using the color red, and its stations are given numbers using the letters "M" for the main line and "Mb" for the branch line.