Formerly known as Tram'y due to its opening-day Y-shape (while T4 got its Y-shape after its initial opening), this tram line goes from the Saint-Denis–Porte de Paris Métro station to Épinay-sur-Seine — Orgemont, with a branch to the university campus of Villetaneuse, where it connects to the more recent T11 Express Line. An extension is also planned south, to Paris itself, at the Rosa Parks RER station. Construction of the line began in 2010; service began in 2014. The southern extension's opening date has not yet been set.
