E231 Series - Variants

Variants

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 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 (10-car sets) and Jōban 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 interrunning 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 10-car sets.