On February 12, 2016[REF] the El Prat branch opened from Aeroport T1 to Zona Universitària stations.
Line 9 is being bored by a single tunnel boring machine (TBM) - where other metros bore a pair of tunnels, one for each direction,[REF] Line 9's extra wide tunnel is wide enough for both the tracks (which are stacked on top of each other), and for the route's stations.