The SNCF Class Z 5600 is a double-deck electric multiple unit trainset that is operated by SNCF 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 and the TER Bourgogne-Franche-Comté regional rail system.
Electric multiple unit trainsets offers a major advantage: the motors can be distributed across the entire train, instead of being concentrated in a locomotive.
This improves traction and therefore accelerations which is useful on suburban commuter rail systems with frequent stops, like the RER.
In order to take advantage of the equipment as quickly as possible, SNCF operated the trailer cars between a pair of Class BB 8500 electric locomotives.
As of 1 January 2022[update], 57 Z8800 trainsets are based at the Les Ardoines (RER C) and Villeneuve (Transilien R) SNCF depots.