[8] All tunneling work was stopped in 2011 due to a lack of funding, a decision taken by the Government of Catalonia in the aftermath of the 2007-2008 financial crisis.

The remaining 4.5 km of tunnel between Lesseps and Campus Nord are expected to be completed by 2030, with a 2 station extension from La Sagrera to Guinardó | Hospital de Sant Pau projected to be in service by 2027.

[10] On 13 December 2009,[11] the section between Can Peixauet and Can Zam, excluding Santa Rosa station, opened to the public.

On February 12, 2016[12] the El Prat branch opened from Aeroport T1 to Zona Universitària stations.

However, three stations – Aeroport Terminal de Càrrega, La Ribera and Camp Nou – did not open, as the first two were built to serve future developments and the latter had to remain closed due to technical reasons (as one of the line's main construction sites).

Entering or exiting the line from the Barcelona Airport stations, Aeroport T1 and Aeorport T2 requires a valid ticket.

A Single Ticket (Bitllet Senzill), a T-casual (formerly T-10), or a T-familiar are not considered valid, and will not allow exiting the line through these stations.