|A typical Madrid metro entrance, at Tribunal station|
|A modern metro train on line 9|
It is one of the largest metro systems in the world, which is especially remarkable considering Madrid's population of approximately four million. In fact, it is the sixth longest metro in the world, though Madrid is approximately the fiftieth most populous metropolitan area in the world. It is also one of the fastest growing in the world, rivalled only by Seoul; the latest round of expansions, completed in spring 2003, have increased its length to 223 kilometres.
Starting in the 1970s, it was sequentially greatly expanded to cope with the influx of population and urban sprawl from Madrid's economic ascendancy. A huge project in the late 1990s and early 2000s installed approximately 50 kilometres of new metro tunnels, including a direct connection between downtown Madrid and Barajas International Airport (line 8), and service to outlying areas, including a huge 40-kilometre loop called Metrosur (line 12) serving Madrid's southern suburbs.
Metrosur, the largest civil engineering project in Europe, opened on April 11, 2003. It includes 40.7 kilometres of tunnel and 28 new stations (including an interchange station and an additional station on Line 10, which connects it to downtown). Construction began in June 2000, the whole loop was completed in less than three years. It connects the towns of Getafe, Móstoles, Alcorcón, Fuenlabrada, and Leganés.
Madrid also has an extensive commuter train (Cercanías) network operated by Renfe, the national rail line, which is intermodal with the metro network. Several Cercanías transfer stations were included in Metrosur.
Madrid's metro consists of the following lines. See also List of Madrid metro stations.
|Number||Western terminus||Eastern terminus||Stations|
|Line 1||Plaza de Castilla||Congosto||27|
|Line 2||Cuatro Caminos||Ventas||15|
|Line 4||Argüelles||Parque de Santa Maria||20|
|Line 5||Casa de Campo||Canillejas||30|
|Line 7||Pitis||Las Musas||22|
|Line 8||Nuevos Ministerios||Barajas||6|
|Line 9||Herrera Oria||Arganda del Rey *||26|
|Line 10||Puerta del Sur||Fuencarral||19|
|Line 11||Pan Bendito||Plaza Elíptica||3|
|Line R†||Príncipe Pío||Ópera||2|
* Includes light rail from Puerta de Arganda to Arganda del Rey (5 stations)
† For Ramal, "branch"
The metro is operated by its own company, under the Department of Public Works, City Planning, and Transportation of the autonomous community of Madrid.