text: holstein ( station ) holstein is a station on the sognsvann line ( line 6 ) of the oslo metro in norway . the station is located between kringsjå and østhorn stations . holstein was opened during the second world war , in 1941 . formerly nordberg was the next southbound station , but it was closed in 1992 , at the same time as holstein was re - built with longer platforms and new ticket machines . the name holstein is believed to origin from schleswig - holstein in germany . history the sognsvann line opened on 10 october 1930 . it was built by akersbanerne , and ran from majorstuen to sognsvann station . the line was double - tracked from majorstuen to korsvoll , and single - tracked from there to sognsvann . in 1939 , the section korsvoll – sognsvann was upgraded to double tracks , and the station korsvoll had its name changed to østhorn . two years later , holstein was opened , although the accurate date of opening remains undisclosed . in 1990 , it was decided to upgrade the sognsvann line to metro standard , which involves a heightening and lengthening of the platforms , installation of third rail power supply and a new signaling system . many residents feared that holstein station would be closed together with frøen , but only the latter was closed . the upgrade started three years later , when tåsen station was moved 150 metres ( 490 ft ) further north , and nordberg station was closed . holstein was closed for traffic during the construction period . were built at both holstein and nordberg stations , and new ticket machines were installed at holstein station . service holstein is served by the line 6 on the sognsvann line , operated by oslo t - banedrift on contract with ruter . the rapid transit serves the station every 15 minutes , except in the late evening and on weekend mornings , when there is a 30 - minute headway . travel time along the 7 . 1 - kilometre ( 4 . 4 mi ) portion to stortinget in the city center is 13 minutes . the station provides correspondence to the bus lines 22 and 25 in carl vei , a two minutes walk away . facilities holstein has two platforms , each with a wooden shed . the sheds are designed by arne henriksen in a minimalist and standardised style with constructions of wood and steel . located between the streets and , the station serves the residential area nordberg . there is a kindergarten and a senior center close to the station . the origin of the station 's name is disputed . professor h. o. christophersen stated in 1952 that it from the german region holstein . journalist arvid sagen stated in 2001 that the name owed its origins to the norwegian word " hole " ; which means a round hill , and " " , which means stone .