Storstockholms Lokaltrafik in the context of "Stockholm commuter rail"

The Stockholm Metro (Swedish: Stockholms tunnelbana) is a rapid transit system in Stockholm, the capital city of Sweden. Its first line opened in 1950 as the first metro line in the Nordic countries. Today, the system consists of three lines and 100 stations, of which 47 are underground and 53 above ground. The system is owned by Region Stockholm via SL, the public transport authority for Stockholm County. It is the only metro system in Sweden.

The metro's three coloured lines, Green, Red, and Blue, together form seven routes with different termini. All of these routes pass through the city centre, creating a highly centralised network. The main interchange for all three lines is T-Centralen station, where they intersect. In addition to T-Centralen, the system has three other interchange stations: Fridhemsplan, Slussen, and Gamla stan. Various extensions to the system are currently under construction, An extension to the north-west of Blue Line is expected to open in 2027, while extensions to its south are expected to open in 2030. Construction of a new Yellow Line to the west of the city centre is scheduled to start in 2025.

The Red line (Swedish: Röda linjen; officially Metro 2, but called Tub 2 ("Tube 2") internally), is one of the three Stockholm Metro lines. It has a total of 36 stations, of which four are cut and cover, 16 are tunneled, and 15 are on the surface. The line is a total of 41.238 kilometres (25.624 mi) long. It consists of four branches with terminals in Fruängen and Norsborg in the southwest and Mörby centrum and Ropsten in the northeast.

The "Red line" designation began in the late-1970s, and officially only since the 1990s, and comes from the fact that the route has been marked in red on Storstockholms Lokaltrafik's maps at least since the 1970s. Previously, the Red line had been coloured orange on the system map, but as new maps were printed with changes, the colour became increasingly redder in the 1980s.