# SNCF Class Z 20900

The SNCF Class Z 20900 is a double-deck, dual-voltage electric multiple unit trainset that is operated on line C of the Réseau Express Régional (RER), a hybrid suburban commuter and rapid transit system serving Paris and its Île-de-France suburbs.
The 54 four-car trains were built by a consortium of French manufacturer Alstom and Canadian conglomerate Bombardier between 2001 and 2004. The first set was placed into regular passenger service in July 2001.
They are the final equipment produced as part of the Z 2N series of trainsets, which were continuously improved over several generations.
The introduction of the Z 20900 allowed for the oldest equipment on the RER C to be scrapped.

## Description

SNCF ordered the Class Z 20900 at the end of 1998 to complete the rolling stock fleet of line C and to replace the last 42 Z 5300 units still in service. The design of 54 four-car trainsets would be based on the earlier Z 20500.They are distinguished in particular by :
* large, much more comfortable seats with armrests
* their fixed composition at 4 cars
* the Alstom OniX traction chain (Onduleur à Intégration eXceptionnelle) based on IGBT components.
* the installation of the end-of-evening security system by the possibility of neutralizing the passenger spaces of the power cars
* air conditioning and tinted windows
* the inter-circulation between the two central car;
* luminous and audible warning device for the closing of the doors
The two power cars (ZB) have 82 seats while the two trailers (ZRB) each have 96, as well as a toilet.

## History

In order to complete the rolling stock of line C of the RER, and to eliminate from the line the last Z 5300 units still in service, the SNCF ordered new Z 20500 type trainsets at the end of 1998, but with various engine and amenagement upgrades. These new components were delivered from July 2001 to 2004 and were numbered Z 20900. Their delivery made it possible to eliminate, by shifting, the first sub-series of Z 6100 in the northern suburbs. Between 2001 and 2012, 12 trains were used for the line H.
The OniX traction motor was tested on unit Z 20887-20888(Z20500 series), and is used on all trains of this series. This propulsion system is also used in Z 23500 (TER 2N) and CP 3500.

## Formations

As of 1 January 2022, 54 Z20900 trainsets are based at the Les Ardoines SNCF depot.
As shown below, they are formed with two motored cars and two non-powered (trailer) cars (2M2T).
| | ← Versailles/Pontoise/St Quentin-en-YvelinesJuvisy/Massy-Palaiseau/Saint-Martin-d'Étampes → | ← Versailles/Pontoise/St Quentin-en-YvelinesJuvisy/Massy-Palaiseau/Saint-Martin-d'Étampes → | ← Versailles/Pontoise/St Quentin-en-YvelinesJuvisy/Massy-Palaiseau/Saint-Martin-d'Étampes → | ← Versailles/Pontoise/St Quentin-en-YvelinesJuvisy/Massy-Palaiseau/Saint-Martin-d'Étampes → |
| Car No. | 1 > | 2 | 3 | < 4 |
| Type | Motor | Trailer | Trailer | Motor |
| Numbering | Z 209xx (odd number) | ZRB 2019xx (odd number) | ZRB 2029xx (odd number) | Z 209xx (even number) |
* < or > show a pantograph. Cars 1 and 4 are each equipped with one pantograph.
* Cars 2 and 3 are connected by a gangway.

## Fleet

The number of Z 20900 trainsets is 54, numbered 201 A to 254 A (the index "A" indicating asynchronous motorization). All are in service on line C of the Île-de-France RER and are managed by the technical supervision of the line C fleet (SLC).
* Listing Fleet Z20900 (in french)

## Gallery

* Z 20900 in the SNCF livery
* Z 20900 in the navy blue Transilien livery
* Z 20900 interior, upper deck (original)
* Z 20900 interior, the mid-deck wide entry, and stairs to lower deck, as seen from the upper deck
* Operators compartment
* Z 20900 interior (refurbished)