Copenhagen Metro (Danish: Københavns metro) is a rapid transit serving Copenhagen, Frederiksberg and Tårnby in Denmark. The 20.5-kilometer (12.7 mi) system opened between 2002 and 2007, and has two lines, M1 and M2. The driverless light metro supplements the larger S-train rapid transit system, and is integrated with DSB local trains and Movia buses. Through the city center and west to Frederiksberg, both M1 and M2 share a common line. To the south-east the system serves Amager, with the 13.7-kilometer (8.5 mi) M1 running the new neighborhood of Ørestad, and the 14.2-kilometer (8.8 mi) M2 serves the eastern neighborhoods and Copenhagen Airport. The metro has 22 stations, of which 9 are underground. In 2009, the metro carried 50 million passengers.