The Lambertseter Line (Norwegian: Lambertseterbanen) is a 5.9-kilometer (3.7 mi) line on the Oslo Metro which runs from Brynseng to Bergkrystallen. It further shares track with the Østensjø Line along the 2.5-kilometer (1.6 mi) section from Tøyen to Brynseng. The line runs through a primary residential area of Nordstrand, serving neighborhoods such as Manglerud, Ryen and Lambertseter. The line is served by Line 4 of the metro, which runs every fifteen minutes. This is supplemented by Line 1 that is extended to Bergkrystallen between 6:30 and 19 on weekdays, giving a combined frequency of eight trains per hour.