The Sognsvann Line serves the northwestern and northern neighborhoods of Oslo, mostly within the borough of Nordre Aker.

In 1993, it was upgraded to metro standard as the first light rail west of Oslo, with two stations being closed.

Sognsvann serves the Norwegian School of Sport Sciences and the recreational area Nordmarka.

The neighborhoods of Sogn and Tåsen were being built, and the municipality wanted to establish a good transport system to make the areas more attractive.

[1] In 1920, Holmenkolbanen applied to build a branch from Frøen via Tåsen to Nydalen and Grefsen, along what is today the Ring Line.

The line was upgraded to metro standard by replacing the overhead wire with a third-rail power supply and installing automatic train protection.

The third rail required all level crossings to be removed, resulting in the line being rebuilt several places to allow the road to underpass or overpass.

The light rail permitted passengers to cross the lines at the stations, but this was made impossible with metro standard.

All platforms have a shed; Ullevål stadion has a larger weather cover and has a design inspired by football.

[13][14] The new light rail started services on 1 June 1999,[15] and the rapid transit station opened on 22 August.

[19] The company also considered building the ring as part of the tramway, and have combined operation with both tram and metro on the Sognsvann Line.

[21] Many neighbors to the Sognsvann Line complained about the proposal, stating that they had hoped that the section from Majorstuen to Berg would have been rebuilt as a tunnel.

[28] In 2002, the Sognsvann Line was closed during the summer vacations due to improvements of the track and third rail.

[33][34] The operation of the line was replaced by buses that served temporary stops in Nordbergveien and Sognsveien.

[35] In 2010, a truck was stuck under the train bridge between Holstein and Kringsjå over Carl Kjeldsens vei.

[37] The line branches off from the Common Tunnel after Majorstuen, and heads northwards through the borough of Nordre Aker.

[8] North of Berg, the Sognsvann Line mainly serves residential areas, including student dormitories at Sogn and Kringsjå.

[42] The Norwegian School of Sport Sciences and the National Archival Services of Norway is served by Sognsvann Station.

Transfer to Oslo Central Station, which serves all mainline trains in Eastern Norway, is available at Jernbanetorget.

[46] The Oslo Tramway can be reached from Majorstuen and Forskningsparken, as well as in the city center from Jernbanetorget, Stortinget and Nationaltheatret.