The line was created on 30 June 2008, replacing tram routes
55 and
56. Together with tram routes
4,
7,
8 and
9, it was one of five 'chrono' lines, which means that it was served by
low-floor high-capacity trams with a high frequency. The low line number chosen for the new line shows that it is either a metro line or a 'chrono' line. From 31 August 2009, lines 3 and 4 changed their northern termini. Whereas line 3 used to end at
Brussels-North railway station, it then continued all the way to Esplanade, while line 4 was shortened to terminate at Brussels-North. Because of this, the very long line 4 and the short line 3 were then equalised. Before the line was taken out of service for a while, the line was serviced by both the modern low-floor trams (the
T3000 and
T4000), as well as the older two-part PCC-trams (
T7700 and
T7800). After its return in 2008, the line was serviced by the modern low-floor trams only, mostly of the T4000 type. On 23 September 2024, the line was permanently discontinued on the occasion of the opening of the new tram line 10, which took over most of its route. ==Route==