The Citadis is a family of low-floor trams (streetcars) and light rail vehicles built by Alstom. More than 1140 Citadis trams are in use in over 28 cities, including: Bordeaux, Grenoble, Lyon, Montpellier, Rouen, Orléans, the Paris area, Nottingham, Algiers, Oran, Constantine, Barcelona, Dubai, Dublin, Istanbul, Gdańsk, Katowice, Adelaide, Melbourne, Jerusalem, Rabat, Casablanca, Tunis and Rotterdam outside France. An evolution of Alstom's earlier TFS vehicle, most Citadis trams are made in Alstom's factories in La Rochelle, France, Barcelona, Spain,and Annaba, Algeria.
The Citadis family includes both partial and fully low-floor trams and LRVs, in versions with three (20x), five (30x), seven (40x), and nine (50x) sections.
The services employs the following standard variants:
Citadis 401 – five sections, 70% low floor (Montpellier and Dublin, some converted from 301s)
Citadis 402 – seven sections, 100% low floor (Bordeaux, Dublin, Grenoble, Lyon, Paris T3, Dubai, Rio de Janeiro, Oran, Constantine)
Citadis 502 – nine sections, 100% low floor (Dublin - on order)
Like most trams, Citadis vehicles are usually powered by overhead electric wires collected by a pantograph, but the trams in several places do not use pantograph current collection entirely.
The most popular solution is Alstom's proprietary ground-level power supply (APS, first used in Bordeaux and subsequently in Angers, Reims, Orleans, Tours, Dubai, and in the future, Sydney), consisting of a third rail which is only powered while it is completely covered by a tram so that there is no risk of a person or animal coming into contact with a live rail.
On the networks in France and in Sydney, the trams switch to conventional overhead wires in outer areas, but the Dubai vehicles are the first to employ APS for its entire passenger length (although they are still equipped with pantographs for use in the maintenance depot).
Another option is to use on-board batteries to store electrical power, allowing brief periods of catenary-free operation without the need to install special infrastructure. The Citadis trams in Nice operate off a set of nickel metallic hydride batteries in two large open spaces where overhead wires would be an eyesore.
