As of January 2015[update], the ATM-managed public transport system comprises 50 different operating companies and serves 346 municipalities, accounting for a population of over 5.7 million.

There currently exist about 80 different types of multiple-time tickets or unlimited passes for use on the STI, all of which allow free-of-charge interchange between transport modes in a single trip.

The STI consists of six concentric fare zones centered in Barcelona, numbered 1–6, which are further divided into sectors lettered A–H.

[5][7] Although the Berguedà and Ripollès comarques were incorporated in the STI on 1 January 2015, they do not appear on official maps because of their distinct operation.

[10] Nevertheless, there are the following exceptions: There are eight basic types of fare-integrated cards—the T-10, T-50/30, T-70/30, T-Mes, T-Jove, T-Trimestre, T-Dia and T-16—, all of which are multiple-time tickets or unlimited passes allowing free-of-charge interchange between transport modes in 1 hour and 25 minutes within one fare zone (plus 15 minutes for each additional zone).