E231 series


The E231 series is an electric multiple unit train type used for commuter and outer-suburban services operated by East Japan Railway Company in Japan since 2000.

Design

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, and the prototype train built in 1998 for trials on the Chūō–Sōbu Line was actually classified 209-950 series, later becoming E231-900 series. Full-production E231-0 series trains were subsequently introduced on the Chūō–Sōbu Line and Jōban Line. 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 Tozai 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 Tōkaidō Main Line south from Tokyo. From 2004 onward, two bilevel Green cars were inserted into all E231-1000 series ten-car sets.

Variants

Originally, 46 ten-car sets were based at Mitaka Depot for use on Chūō–Sōbu Line services, replacing the earlier 103 and 201 series fleet, and 17 ten-car sets and 19 five-car sets were based at Matsudo Depot for use on Jōban Line services between Ueno and Toride, and also Narita Line services to Narita, replacing the earlier 103 series fleet. On the Chūō–Sōbu Line, sets B1 to B42 were delivered between February 2000 and November 2001, set B57 was delivered in November 2002, and sets B80 to B82 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. The Jōban Line fleet was delivered between November 2001 and February 2005, with the first trains entering service on 3 March 2002.
Between 2015 and 2020, most of the Chūō–Sōbu Line sets were displaced by E231-500 series trains transferred from the Yamanote Line. Of the 46 sets, by the end of 2020, all six-door cars will have been scrapped and the remaining cars reformed into 2 ten-car Jōban Line sets, 32 eight-car Musashino Line sets, and 6 four-car Hachikō Line/Kawagoe Line sets, while 6 reformed ten-car sets will remain on the Chūō–Sōbu Line.
In 2015, 20 cars from former sets B20-B22 were reformed and transferred to the Jōban Line to form two ten-car sets, bringing the total to 19 ten-car sets.
In October 2017, 8 cars from former sets B5 and B22 were reformed as the first Musashino Line eight-car set and entered service in November 2017.
The first reformed E231-0 series Chūō–Sōbu Line train, numbered set B11 and composed of 8 cars of former set B11 and 2 cars of former set B5, completed refurbishment on 24 April 2018 and was entered into service on 21 May 2018. The last non-reformed trains, sets B80 and B82, were removed from service after 13 March 2020.

Lines served

10-car Chūō–Sōbu Line sets (since 2018)

, six ten-car sets are based at Mitaka depot in Tokyo and formed as shown below with six motored cars and four non-powered trailer cars.
, 19 ten-car sets are based at Matsudo depot in Chiba Prefecture and formed as shown below with four motored cars and six non-powered trailer cars.
, 19 five-car sets are based at Matsudo depot in Chiba Prefecture and formed as shown below with two motored cars and three non-powered trailer cars.
, 30 eight-car sets are based at Keiyō Depot and formed as shown below with four motored cars and four non-powered trailer cars.

10-car Chūō–Sōbu Line sets (2002 to 2020)

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 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 SaHa E231-600 cars incorporated some elements from the newer E233 series. Meanwhile, the new SaHa E231-4600 cars were built almost fully to E233 series standards; they also 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 Chūō–Sōbu Line livery. It entered revenue service on the Chūō–Sōbu Line from 1 December 2014. A second set, former Yamanote Line set 540 was converted to a ten-car set for use on the Chūō–Sōbu Line in May 2016, renumbered A540. Between 2017 and 2020, the remaining sets were transferred to the Chūō–Sōbu Line as the E235 series continues to replace them on the Yamanote Line. 48 of the 52 SaHa E231-4600 cars built from 2010 to 2011 were updated to E235 series standards, while the remaining 4 cars are stored in Tokyo General Rolling Stock Centre. The last set of E231-500 on the Yamanote Line finished service in January 2020 and was converted for service on the Chūō–Sōbu Line as set A506.

Lines served

10-car Chūō–Sōbu Line sets

, 52 ten-car sets are based at Mitaka depot in Tokyo and formed as shown below with six motored cars and four non-powered trailer cars.

11-car Yamanote Line sets (2010 to 2020)

Special liveries

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.

E231-800 series

Seven ten-car sets based at Mitaka Depot for use on Chūō–Sōbu Line and Tokyo Metro Tozai Line interrunning services. These sets were delivered between January and May 2003, entering service on 1 May 2003.

Lines served

, seven ten-car sets are based at Mitaka depot in Tokyo and formed as shown below with six motored cars and four non-powered trailer cars.
This was the prototype E231 series set, built jointly by Tokyu Car and JR East's Niitsu factory, and delivered in October 1998 for the Chūō–Sōbu Line, classified as 209-950 series. It was reclassified as E231-900 series in June 2000.
On February 25, 2020, it operated its last revenue service on the Chūō–Sōbu Line. The set was refurbished at Ōmiya Rolling Stock Center between March 3 and July 10 for transfer to the Musashino Line and associated through services and reentered service on July 20.

Lines served

8-car Musashino Line

, one eight-car set is based at Keiyō Depot and formed as shown below with four motored cars and four non-powered trailer cars.

10-car Chūō–Sōbu Line (2000 to 2020)

One ten-car set was based at Mitaka depot in Tokyo and formed as shown below with four motored cars and six non-powered trailer cars.
These trains are designed for longer-distance suburban services, and include toilets, transverse seating bays, and bilevel Green cars. The Ito Line and Joetsu Line mainly use 5-car sets, while the Shōnan–Shinjuku Line, Ueno–Tokyo Line, Takasaki Line, Tōkaidō Main Line, Utsunomiya Line use 10- or 10+5-car sets.

Lines served

Ten- and five-car suburban sets based at Oyama and Kōzu depots for use on the following lines.

10-car K sets

, 42 ten-car sets are based at Kōzu depot in Kanagawa Prefecture and formed as shown below with four motored cars and six non-powered trailer cars.
, 49 ten-car sets are based at Oyama depot in Tochigi Prefecture and formed as shown below with four motored cars and six non-powered trailer cars.
, 34 five-car sets are based at Kōzu depot in Kanagawa Prefecture and 35 five-car sets are based at Oyama depot in Tochigi Prefecture. They are formed as shown below with two motored cars and three non-powered trailer cars.

E231-3000 series

From 2017, former E231-0 series ten-car sets based at Mitaka Depot for use on Chūō–Sōbu Line services were reformed and converted to become four-car E231-3000 series sets based at Kawagoe for use on Kawagoe Line and Hachikō Line services. The first set entered revenue service on the line on 19 February 2018.

Lines served

, six four-car sets are based at Kawagoe depot in Saitama and formed as shown below with two motored cars and two non-powered trailer cars.
The former identities of the E231-3000 series sets are as follows.