The Milan S Lines constitute the commuter rail system serving the metropolitan area of Milan, Italy. The system comprises 11 lines serving 124 stations, for a total length of 403 km. There are 415 trains per day with a daily ridership of about 230,000. The core of the system is the Passante, an underground railway running through the city approximately from the north-west to the south-east. Several lines share this track, making the service in the city centre comparable to a metro line or S-Bahn system. The service timetable is based on a clock-face scheduling. Although operated by different companies, the Milan Metro and the suburban rail service have integrated tickets. Network Lines in darker background run through the Milan Passante railway. Lines which share same tracks for the majority of the route are generally identified by similar colors. Trains run every 30 minutes in each line, generally from 6 am to 9 pm or midnight depending on the line. Defunct lines Stations served Integrated ticketing An integrated ticket is used inside the Milan urban area for bus, tram and metro lines, as well as the suburban railway. The urban single journey ticket costs €2.00. Other tickets are available, including 24h and 48h tickets and night ticket. Regional train fares apply outside the urban limit. Between 2004 and 2007 ATM introduced Itinero smartcard, a proximity card which can be charged with season tickets, replacing paper for this type of tickets in the Milan area. At the beginning of 2010, a new smartcard, RicaricaMi, was introduced. The new card can be charged up with credit and can be used for travel in place of magnetic paper tickets, on the model of London's Oyster card. These cards are also valid on the suburban railway lines. The suburban railways can be accessed also with the regional integrated ticket "Io viaggio ovunque in Lombardia", as 1 to 7 days tickets or more long subscription with smartcard "Io Viaggio". Rolling stock Several train classes are operated on the network. TAF (Treno Alta Frequentazione) class trains were introduced since the end of the 1990s. Trenord is now introducing new Treno Servizio Regionale (TSR) class trains to replace older rolling stock. History Full service started on 12 December 2004 with the completion of the Passante and the activation of the first 8 lines. However, a shuttle service was running since 1997 in the partially completed track. Line