proceeding to the end of the Sognsvann Line. Line 4, also with a 15-minute headway, serves all the stations on the ring except Carl Berners plass. As with Line 5, trains originate on the Grorud Line in the northeast, but they branch off at Økern and enter the Ring via the Løren Line. Line 4 trains then run counter-clockwise through most of the ring, branching off at Tøyen and continuing on the Lambertseter Line. Travel time from Nydalen and Storo stations to the city centre stations is about the same, independent of which direction on the Ring Line travellers choose. Passengers heading for the city centre can therefore take the first train that comes, independent of which direction it is heading, thus giving Nydalen and Storo a five-minute headway service to the city centre. The trains are operated by Sporveien T-banen, a subsidiary of Sporveien, on contract with the public transport authority Ruter. Transfer to the Kolsås-, Røa- and Holmenkoll Line is available at Majorstuen; transfer to the Lamberseter, Østensjø- and Furuset Line is available at Tøyen and transfer to the Grorud Line is available at Carl Berners plass. Transfer to Oslo Central Station, which serves all trains in Eastern Norway, is available at Jernbanetorget. Most west-bound trains can also be reached at Nationaltheatret, and trains along the Gjøvik line can be reached at Nydalen Station, that is close, but not adjacent, to Nydalen Metro Station. The Oslo Tramway can be reached from several stations. In the city centre, transfer to all lines is possible at Jernbanetorget (except line 13, which stops close at Dronningens gate); All the lines can also be reached at Stortinget, but lines 11, 12 and 13 stops at Øvre Slottsgate while lines 17, 18 and 19 stops at Tinghuset. Lines 11 and 13 can also be reached at Nationaltheatret. Lines 11, 12 and 19 all terminate at Majorstuen; lines 17 and 18 run via Forskningsparken; lines 11, 12 and 18 can be reached at Storo; and line 17 runs past Carl Berners plass. References Oslo Metro lines Railway loop lines Railway lines opened in 2003 2003 establishments in Norway