offices complexes. At Brynseng lines continue concurrently across a bridge over the Trunk Line and then the Østensjø Line and trains heading towards the Furuset Line branch off towards Hellerud Station. The Lambertseter Line continues to Høyenhall Station. The line continues along Ring 3 and passes Manglerud Station and Ryen Station. After the station there is a turn-off to Ryen Depot, while the main line itself continues to climb Ekebergåsen, reaching Brattlikollen Station. The line continues past the stations of Karlsrud, Lambertseter and Munkelia. After the latter the line turns ninety degrees, passes through a tunnel before reaching the terminus, Bergkrystallen. Service The Lambertseter Line proper is served by Line 4 of the Oslo Metro. Most of the week it runs four services per hour, although there are reduced services during late evenings and parts of the weekend. Line 4 runs through the Common Tunnel and continues along the Ring Line, Løren Line and Grorud Line towards Vestli. Supplemental service is provided by Line 1 which connects to the Holmenkollen Line towards Frognerseteren (station) in the west. Operations of the lines are done by Sporveien T-banen on contract with Ruter, the public transport authority in Oslo and Akershus. The infrastructure itself is owned by Sporveien, a municipal company. Service is provided using MX3000 three- and six-car trains. Travel time from Bergkrystallen to Brynseng is 12 minutes and from Bergkrystallen to Stortinget is 22 minutes. The line had 8,000 weekday average boarding passengers in 2002, making it the least trafficked of the eastern metro lines. History Planning The first plans to build a tramway along part of the route of the Lambertseter Line were launched by Ekebergbanen. They had opened the Ekeberg Line in 1917, which was supplemented with a branch, the Simensbråten Line, in 1931. Ekebergbanen proposed extending the branch along the route of the Lamberseter Line between Ryen and Brattlikollen. The terminus was planned at about Munkelia. The Ekeberg og Simensbråten lines were both light rails in their own exclusive right of way. However, the final section into the city center used street lines in mixed traffic along the Gamlebyen Line. Since 1919, there had been plans to connect the Ekeberg Line with the Holmenkollen Line on the west side of town via a tunnel. Along part of the stretch, this connection was planned elevated. Due to the German occupation of Norway from 1940 to 1945, all plans and