Line 1, shortened to L1, coloured red and often simply called Línia vermella ("Red Line"), is the second oldest Barcelona Metro line, after line L3. It is the longest line of the Barcelona Metro, and links L'Hospitalet de Llobregat and Santa Coloma de Gramenet. Originally operated by the independent Ferrocarril Metropolitano Transversal de Barcelona, it is today operated by Transports Metropolitans de Barcelona (TMB) and is part of the ATM fare-integrated main transport system. L1 is the only metro line in Spain to use Iberian gauge tracks, as used by most Spanish main line railways.