|In service 2000–Present|
|Built at Niitsu, Kobe, Yokohama|
Number built 2,736 vehicles
|Manufacturer JR East, Kawasaki Heavy Industries, Tokyu Car Corporation|
Replaced 103 series, 113 series, 115 series, 201 series, 205 series, 301 series
The E231 series (E231系, E231-kei) is an electric multiple unit (EMU) train type used for commuter and outer-suburban services operated by East Japan Railway Company (JR East) in Japan since 2000.
Trains were manufactured by Tokyu Car Corporation, Kawasaki Heavy Industries and also at JR East's factory at Niitsu in Niigata Prefecture.
The type evolved from the earlier 209 series and E217 series EMUs, with the main visible difference being wider bodies (2,950 mm compared to the 2,800 mm for earlier commuter trains), and the prototype train built in 1998 for trials on the Chuo-Sobu Line was actually classified 209-950 series, later becoming E231-900 series. Full-production E231-0 series trains were subsequently introduced on the Chuo-Sobu Line (10-car sets) and Joban Line (10+5-car sets). Other variants include the 11-car E231-500 series for the Yamanote Line, and the E231-800 series with 2,800 mm wide bodies and end doors for use on Tokyo Metro Tōzai Line inter-running services.
From 2000 onward, the first E231-1000 series outer-suburban variant was delivered for use on Utsunomiya Line and Takasaki Line services north from Ueno Station in Tokyo. These trains included transverse seating in some cars and were also equipped with toilets. Production continued into 2006 with trains delivered for use on the Tokaido Main Line south from Tokyo. From 2004 onward, two bilevel Green cars were inserted into all E231-1000 series ten-car sets.
46 ten-car sets (Sets B1-42, B57, B80-82) based at Mitaka Depot for use on Chuo-Sobu Line services, replacing the earlier 103 and 201 series fleet. Sets B1 to B42 were delivered between February 2000 and November 2001. Set B57 was delivered in November 2002. Sets 80 to 82 were delivered between October and November 2006. The first sets entered service on 13 March 2000. These sets each include one "six-door" SaHa E230 car (car 5).
17 ten-car sets (101 to 117) and 19 five-car sets (121 to 139) based at Matsudo Depot for use on Joban Line services between Ueno and Toride, and also Narita Line services to Narita, replacing the earlier 103 series fleet. The fleet was delivered between November 2001 and February 2005, with the first trains entering service on 3 March 2002.
10-car Chuo-Sobu Line sets
As of 1 April 2014, the fleet consists of 46 ten-car sets, based at Mitaka depot in Tokyo, and formed as shown below with four motored ("M") cars and six non-powered trailer ("T") cars, and car 1 at the Chiba (eastern end).
10-car Joban Line sets
As of 1 April 2014, the fleet consists of 17 ten-car sets, based at Matsudo depot in Chiba Prefecture, and formed as shown below with four motored ("M") cars and six non-powered trailer ("T") cars, and car 1 at the Ueno (southern end).
5-car Joban Line sets
As of 1 April 2014, the fleet consists of 19 five-car sets, based at Matsudo depot in Chiba Prefecture, and formed as shown below with two motored ("M") cars and three non-powered trailer ("T") cars, and car 11 at the Ueno (southern end).
A fleet of 52 11-car E231-500 series was delivered from January 2002 to April 2005 for use on Yamanote Line services, replacing the earlier 205 series fleet. The first trains entered service on 21 April 2002. These trains include D-ATC digital automatic train control, and feature pairs of LCD passenger information screens above each door internally. These screens also show advertisements.
Each 11-car set originally contained two six-door SaHa E230 trailer cars (cars 7 and 10) with six pairs of doors per side and bench seats that were folded up until 10 a.m. on weekdays to provide standing room only during the morning peak. From 22 February 2010, the seats were able to be used during the morning peak. The two six-door cars in each set were subsequently replaced by a new build of four-door trailer cars between February 2010 and August 2011, to standardize door spacing ahead of the introduction of platform doors on all Yamanote Line stations by 2017. The new cars were built to E233 series standards, and the replacement cars (SaHa E231-4600) for car 10 have an irregular door spacing corresponding to the driving cars of Keihin-Tohoku Line E233-1000 series sets, which occasionally have to share the same platforms during engineering work. This results in interior seating arranged 3-7-7-5-4, instead of the normal 3-7-7-7-3 arrangement. The first batch of replacement four-door SaHa E231-600 and SaHa E231-4600 cars were delivered from JR East's Niitsu factory on 1 February 2010.
In October 2014, former Yamanote Line set 520 was released from overhaul as a ten-car set, numbered A520, allocated to Mitaka Depot, and finished in the yellow Chuo-Sobu Line livery. It entered revenue service on the Chuo-Sobu Line from 1 December 2014. A second set, former Yamanote Line set 540 was converted to a ten-car set for use on the Chuo-Sobu Line in May 2016, renumbered A540.
As of 31 May 2016, the fleet consists of 50 11-car sets, based at Tokyo General Rolling Stock Centre, and formed as shown below with six motored ("M") cars and five non-powered trailer ("T") cars, and car 1 at the clockwise end.
From 7 September to 4 December 2009, E231-500 series set 502 carried an all-over brown livery to mark the 100th anniversary of the naming of Yamanote Line in collaboration with the Meiji Seika confectionery company.
From 16 January to 28 December 2013, Yamanote Line E231-500 series set 545 operated in an all-over uguisu light green livery to mark the 50th anniversary of the first appearance of 103 series EMUs in this colour scheme.
From 11 October 2014 to 31 March 2015, Yamanote Line E231-500 series set 514 operated in an all-over "red brick" livery to commemorate the 100th anniversary of the opening of Tokyo Station, which opened in 1914.
Seven ten-car sets (K1 to K7) based at Mitaka Depot for use on Chuo-Sobu Line and Tokyo Metro Tozai Line interrunning services. These sets were delivered between January and May 2003, entering service on 1 May 2003.
As of 1 April 2014, the fleet consists of seven ten-car sets (K1 to K7), based at Mitaka depot in Tokyo, and formed as shown below with six motored ("M") cars and four non-powered trailer ("T") cars, and car 1 at the Tsudanuma (eastern end).
One ten-car set based at Mitaka Depot for use on Chuo-Sobu Line services. This was the prototype E231 series set, built jointly by Tokyu Car and JR East's Niitsu factory, and delivered in October 1998, classified as 209-950 series. It was reclassified as E231-900 series in June 2000.
The single ten-car set (B901) is based at Mitaka depot in Tokyo, and formed as shown below with four motored ("M") cars and six non-powered trailer ("T") cars, and car 1 at the Chiba (eastern end).
Ten- and five-car suburban sets based at Oyama and Kōzu depots for use on the following lines.
These trains are designed for longer-distance suburban services, and include toilets, transverse seating bays (in some cars only), and bilevel Green cars (10-car sets only). The Ito Line, Joetsu Line, and Gotemba Line mainly use 5-car sets, while the Shonan-Shinjuku Line, Takasaki Line, Tokaido Line, Utsunomiya Line, and Yokosuka Line use 10- or 15- (10 + 5) car sets.
The E231-1000 series sets are formed as shown below with car 1 (11) at the Atami end and car 10 (15) at the Tokyo/Maebashi end.
10-car U sets
Oyama-based sets U501–541, U584–591
Cars 3 and 8 have one single-arm pantograph each. Cars 1, 5, and 6 have toilets (universal access in car 1).
5-car U sets
Oyama-based sets U2–118
Car 13 has one single-arm pantograph. Car 11 has a toilet (universal access).
10-car K sets
Kōzu-based sets K1–42
Cars 3 and 9 have one single-arm pantograph each. Cars 1, 5, and 10 have toilets (universal access in cars 1 and 10).
5-car S sets
Kōzu-based sets S1–34
Car 13 has one single-arm pantograph. Car 11 has a toilet (universal access).