It forms part of the network of the Lazio regional railways (Italian: ferrovie regionali del Lazio), which is operated by Trenitalia, and converges on the city of Rome, Italy.

Within the territory of the comune of Rome, it plays the role of a commuter railway.

[2] It is estimated that on average about 40,000 passengers travel on an FR5 train each day.

The designation FL5 appears only in publicity material (e.g. public transport maps), in the official timetables, and on signs at some stations.

The FL5, a radial route, runs from the west coast at Civitavecchia in a south easterly direction, via the Pisa–Livorno–Rome railway, to Roma San Pietro, and then around the southern side of Rome's city centre to Roma Termini.