Its name stems from the region of Vallès, which spans two counties north of the Catalan capital.
The region is densely populated, includes the Autonomous University of Barcelona and current public transport services are insufficient for commuters.
Following expressions of citizen support, the Generalitat de Catalunya, the governing body of Catalonia, approved the project in 2010.
The first draft approved by the Generalitat de Catalunya is a 10 km stretch between Montcada i Reixac towards the Autonomous University of Barcelona in Bellaterra (Cerdanyola del Vallès).
However, Plataforma pel Tramvallès demands a 32 km system to be implemented in the area, as proposed by the Plataforma per la Promoció del Transport Públic.