Line 12 (Madrid Metro)

Line 12, also known as MetroSur (Spanish for "MetroSouth"), is a line of the Madrid Metro inaugurated on 11 April 2003. Line 12 is a circle line that is not in the city of Madrid, but links five suburban towns southwest of the city, serving around one million people. The towns linked by Line 12 are Alcorcón, Leganés, Getafe, Fuenlabrada and Móstoles. Despite parts of the line running through uninhabited territory, there are no above-ground sections in an effort to facilitate future urban development. At a total length of 40.6 km, it is the longest line in the network and even more extensive than Lines 9 and 10 with their appendages to the north and south. Despite this, Line 12 accumulated only about 32 million trips in 2018, down from 34.8 million in the previous year, making it the only line to lose users in that time and the third least used after the yet-to-be-completed Line 11 and the airport connection Line 8. This decrease was mainly caused by renovation works necessitating the temporary closure of sections of the line.

The line only interchanges with the rest of the Madrid Metro at one station, with a connection to Line 10 at. There are plans to extend Line 3 to provide a further interchange station at El Casar.

MetroSur is one of the longest tunnels in the world. At the time of its opening it was the second longest fully underground subway in Europe. As of 2024 it remains the longest subway tunnel in the European Union.

Existing
Line 12 stations have elements of art, such as the murals in the Hospital Severo Ochoa Station honoring the Nobel Prize winning biochemist, Severo Ochoa. Surface level stations are covered by massive roofs, with some glass to allow daylight - a similar system is used in Copenhagen Metro and Prague Metro systems.

Proposed
There are plans to build two new stations: "Fuenlabrada Oeste" between and, and secondly "Fuenlabrada Este" between  and. No completion dates for these new stations have been given, as they are still in the planning stage.

Rolling stock
Line 12 uses CAF's 8000 and AnsaldoBreda's 9000 series in MRM composition. Both series use 3-car train, as there is not enough demand, up to three extra coaches per train can be ordered