The present railway is the only part of the old and longer
Rome–Fiuggi–Alatri–Frosinone railway to be in service. The latest shortening of the line occurred in 2008 with the closing of the Giardinetti–Pantano section, which has now become part of the
Metro Line C. The line had been due to be dismantled in 2016 to be replaced with a bus lane along Via Casilina, but in March 2015 it was announced that the line would instead be retained and modernised. , the eastern terminus of the line is at southwestern corner of
Prenestino-Centocelle neighborhood. On 4 March 2026, two trains collided on a
single-track section near Ponte Casilino. There were no injuries, but all service has been suspended since then. A temporary closure of the line had been scheduled for July 2026, for a four-year project to
regauge it to
standard gauge, and it is unknown whether operation at gauge will resume before that planned closure it put into effect. ==References==