The Florence–Rome railway is part of the traditional main north–south trunk line of the Italian railway network. The line is referred to by Ferrovie dello Stato as the Linea Lenta to distinguish it from the parallel high-speed line. The Linea Lenta is now mainly used for regional services, for the InterCity services — rather than the faster Le Frecce trains — between Florence and Rome and for the majority of freight trains. Some types of passenger train are routed on the line to serve smaller stations not served by the high-speed line or in order to improve traffic flow during peak periods or other periods of congestion.

The Empoli–Siena railway is an Italian railway that connects Empoli and Siena. The route follows the valleys of Elsa river as far as Poggibonsi and then the Staggia stream, which were very convenient when the line was planned. The route is in fact flat and substantially straight from Empoli to Poggibonsi, then ascends with wide and long curves through the hills of central Tuscany to Siena.