The idea of a suburban railway network for the city of Milan can be traced back to the 1960s, when the increasing population of the city and the surrounding boroughs made clear the need for a faster and more efficient way to complete medium to longer distance journeys. Designs for an underground railway passing through the city centre were completed at the end of the 1970s, and construction began in 1982, with the work expected to be completed in less than 10 years. Actual work proceeded very slowly, taking 15 years just to open the first part of the track from
Bovisa to
Porta Venezia. From 1997 only a shuttle service was operated on the partially completed track. Two years later the Certosa branch was opened and was completed in 2002 with the opening of the new
Villapizzone station. In the same year the Passante was expanded on the south-east to
Dateo. The cost at that time was already €915 million after 22 years of construction work. The railway was completed in 2008 with the connection to the last station,
Rogoredo. ==References and notes==