railway-like signaling system that advised only about the freedom of the way. Since 1990, the line uses a new signaling system, inspired by the Milan Metro's signaling, that gives information about the speed limit in the section within a range of 0 km/h and 80 km/h. Conductors are informed by classical light semaphores. Line C Line C is an automatic line and uses a radio frequency system for communication with the train. It has an electrical block system that permits a max frequency of a train every 90 seconds. See also List of Rome Metro stations Lazio regional railways 2006 Rome Metro crash List of metro systems Notes References External links The Public transport company of the city of Rome Planned underground and suburban lines on 1986 (archived version) Roma Metropolitane – public transportation website Martin G. Conde, ROME – IMPERIAL FORA. The Velia Hill: Metro 'C' Archaeological Surveys (2006–2007). S10 (b1, b2, b3). (2006–2007) Rome interactive metro map Metropolitan City of Rome Capital Tourism in Rome 1955 establishments in Italy Railway lines opened in 1955