The metro system is owned by the Stockholm County Council through SL, which has contracted the operation to Veolia Transportation. The Stockholm Metro was the site of distribution for the first edition of Metro, now a worldwide chain of free newspapers.
The first part of the metro was opened in 1950, when an underground light rail line from 1933 was converted to metro standard. This line ran south from Slussen to Hökarängen. Over the following years, two more lines extending from Slussen (via Gullmarsplan, then Johanneshov) were opened. In 1952 a second system from Hötorget to the western suburbs was opened. In 1957 the two parts were connected via the Central station and the Old Town, forming the Green line. The Red line was opened in 1964 with two lines going from northeast to southwest via the city center. The third and final system, the Blue line, was opened in 1975 with two lines running northwest from the city center. The latest addition to the whole network yet, Skarpnäck station, was opened in 1994.
Stockholm's metro is well known for its decoration of the stations; it has been called the longest art gallery in the world. This not fully true since some other metros, most notably Moscow has more stations with art. Several of the stations (especially on the Blue line) are left with the bedrock exposed, crude and unfinished, or as part of the decorations. At the Rissne station, an informative wall fresque about the history of Earth's civilizations runs along both sides of the platform.
Trains are operated from 5 am to 1 am, with extended all night service on weekends. All lines have trains every 10 minutes during daytime, reduced to every 15 minutes in early mornings and late evenings, and every 30 minutes during nights. Additional trains in peak hours gives a train every 5–6 minutes on most stations, with 2–3 minutes between trains on the central parts of the network.
|T10||Kungsträdgården – Hjulsta||23 min||14|
|T11||Kungsträdgården – Akalla||22 min||12|
|T13||Norsborg – Ropsten||44 min||25|
|T14||Fruängen – Mörby centrum||33 min||19|
|T17||Åkeshov – Skarpnäck||43 min||24|
|T18||Alvik – Farsta strand||37 min||23|
|T19||Hässelby strand – Hagsätra||55 min||35|
|Entire metro network||100|
There are 271 cars of the C20 stock, and around two hundred Cx stock cars. The green line only uses the new cars, and they are used most of the time on the red and blue lines. However, during rush hours, the older cars can occasionally be seen. Of the older cars the stocks C6, C9, C14 and C15 are still in use.
A single prototype car designated C20F stock is in use. Built on Bombardier's FICAS technology, it has a lighter body, much thinner side walls, and more space compared to the regular C20, by using a sandwich-like composite construction of the body. The C20F weighs 65 metric tons, other exterior measurements are the same as for the C20. The C20F has the same number of seats as the C20, but has space for 323 standing passengers.
The maximum speed is 80 km/h on the Red and Blue lines, 70 km/h on the Green line (50 km/h at the platforms). Maximum acceleration and deceleration is 0.8 m/s². The reason for the lower speed limit on the Green line is due to tighter curves than on the other lines.
To allow close-running trains with a high level of safety, the Tunnelbana uses a continuous signal safety system that sends information continually to the train's safety system. The signal is picked up from the running rails through two antennas placed in front of the first wheel axle and compared with data about the train's speed. Automatic braking is triggered if the train exceeds the maximum permitted speed at any time. The driver is given information about the speed limit through a display in the driver's cabin; in C20 stock, and in Cx stock outfitted for operation with the new signal system installed on the Green line, this is a speedometer with a red maximum speed indicator (needle), while the traditional display in the Cx stock is a set of three lights indicating one of three permitted speeds (High, Medium, Low). The system allows two trains to come close to each other but prevents collisions occurring at speeds greater than 15 km/h. More modern systems also ensure that stop signals are not passed.
Another possibility is ATO, which helps the driver by driving the train automatically. However, the driver still operates the door controls and allows the train to start. ATO is currently only available on the Green line, where a new signal system was installed in the late 1990s. This signal system, together with the C20 rolling stock, permits the use of ATO.
During the 1990s the Stockholm Transit System (SL) started outsourcing protection to private security firms, some of which have been accused of using unlawful methods such as the use of plain clothes guards and heavy-handed treatment of vandals arrested, and even heavy-handed treatment of ticketless riders trying to escape. Since 2005, the Stockholm police have assigned a special task force (Klotterkommissionen) to address the issues. The mainstay among the private security contractors in the fight against graffiti is the Commuter Security Group.