The FL lines, formerly Lazio regional railways (Italian: ferrovie regionali del Lazio, also Ferrovie Laziali) consist of 8 commuter rail lines operated by Trenitalia, converging on the city of Rome. It operates as a combined suburban railway system that connects the city-centre and the outskirts of the city via a commuter rail line.

The FL network, initially made up of two lines and called FM lines (Metropolitan Railways), was formally inaugurated in 1994, following the signing of an agreement between the Lazio Region, the Municipality of Rome, the Province of Rome and Ferrovie dello Stato Italiane, aimed at implementing a new integrated transport structure in the Roman metropolitan and regional area.

Lines FL1, FL2 and FL3 function like a rapid transit service, integrated with the Rome Metro and surface transportation. The other lines (numbered from FL4 to FL8) mostly serve the suburban area of Rome and the Lazio region, and used almost exclusively for commuter traffic.

All eight lines are considered regional trains by Trenitalia. On timetables and departure boards at the stations the trains are marked with the letter R (Regional). The service timetable is based on a clock-face scheduling.

Sections with one train every 15 minutes:

Sections with one train every 30 minutes:

Sections with one train every 60 minutes:

For travel between stations in the City of Rome, ticketing is integrated with the Metrebus Rome system. A passenger may use the integrated ticket "BIT" from €1,50 (valid for 100 minutes) or any other type of integrated ticket or Metrebus pass; in addition, Trenitalia sells special "Anello" tickets where one may travel on any Trenitalia train within the City of Rome with a single €1 ticket (valid for 90 minutes). The "Anello" and the Metrebus Rome tickets are only valid within Rome, bounded by the stations: Capannelle (FL4 and FL6), Cesano di Roma (FL3), Fiera di Roma (FL1), Lunghezza (FL2), Roma Aurelia (FL5), Settebagni (FL1) and Torricola (FL7 and FL8).