The 2000 series is a type of commuter train with four sets of doors per carriage. It is the first four-door commuter train that Seibu developed, and completely new traction and braking systems with regenerative feature were adopted. There are two, four, six and eight-carriage units, and they can be formed of up to ten coaches. They were initially introduced to Seibu Shinjuku Line, where stopping services often caused minor delays at peak times due to congestion. They have been used on Ikebukuro Line as well since 1990.
The 2000 series is classified into two groups: 2000 series in a narrow sense and so-called N2000 series. They look different but share the same traction and braking systems, and thus they can be coupled with each other.
The 2000 series trains were introduced in 1977-88. Some of their parts, such as doors, windows between doors and large fans for ventilation, are similar to those of commuter trains that Japanese National Railways introduced in the 1970s. Gears, motors and traction are almost identical to those of Tokyu 8500 series. They are mostly used on Seibu Shinjuku Line (including smaller lines that branch off), but some ran Ikebukuro Line sporadically. Each unit is formed of two or six coaches (there were also eight-car units in the past).
The N2000 series trains were introduced in 1988-92. 314 carriages in total were introduced, making them the flagship of Seibu. They can be further classified into several groups, but this article does not describe them in detail. They have been used on both Seibu Shinjuku and Ikebukuro Lines as well as other branch lines. Each unit consists of two, four, six or eight coaches, and many of them have been refurbished by the late-2000s.
The N2000 series and 9000 series share the same body and exterior design, but their traction and motors are completely different.
In 2023, an eight-car unit was repainted brown like Seibu trains of old days (to be specific, Musashino Railway 5560 series which was operational in 1928-58), in commemoration of the 110th anniversary of the company.
Current Operations & Future Prospects
The 2000 series (older group) units are used on Seibu Shinjuku and Kokubunji Lines. Two-car units run Ikebukuro Line when there is a shortage of available train, but it is extremely rare in these days. Since they are more than 33 years old, they are likely to retire soon.
The N2000 series are used across the network except Tamagawa, Yamaguchi and Yurakucho Lines. They are particularly common on Seibu Shinjuku Line, and it is hard not to see any of them. However, as the N2000 series is not environmentally friendly, the company is going to gradually replace them with the 40000 series and other "second-hand" trains from Odakyu and Tokyu by early-2031.
