text: ring line ( oslo ) the ring line ( norwegian : t - or ) is the newest rapid transit line of the oslo metro of oslo , norway . it connects to the sognsvann line in the west and the grorud line in the east ; along with these two lines and the common tunnel , the ring line creates a loop serving both the city centre and nordre aker borough . the 5 . 0 kilometres ( 3 . 1 mi ) -long line has three stations : nydalen , storo and sinsen . four - fifths of the line runs within two tunnels , with the 1 . 0 - kilometer ( 0 . 62 mi ) section between storo and sinsen , including both stations , being the only at - grade part . the line connects to the grorud line north of carl berners plass and with the sognsvann line north of ullevål stadion . planning for the line began in the late 1980s , and the city council approved the line 1997 . construction started in 2000 ; nydalen and storo opened on 20 august 2003 , and sinsen opened on 20 august 2006 . the line cost nok 1 , 348 million to build and was financed through oslo package 2 . the ring line is served by lines 4 , 5 and 6 of the metro , operated by sporveien t - banen on contract with the ruter transport authority . all lines operate each fifteen minutes . nydalen and storo are such located that trains in either direction use the same time along the loop , effectively giving a five - minute headway to the city centre . after the opening of the line , the areas around the stations have had increased urban redevelopment . the infrastructure is owned and maintained by the municipal company sporveien . history by the 1960s , oslo had a rapid transit network that branched out north - east and north - west from the city centre . in 1987 , the western and eastern network were connected , and through - trains started operating between the two networks from 1993 . plans to make a second connection through the borough of nordre aker were launched by politicians in the 1980s . it was argued that this was cheaper than building roads , with the per - kilometre price being about a quarter of that for motorways . some politicians also saw the ring line as an opportunity to close all parts of the oslo tramway , except the and lilleaker line . oslo sporveier , the contemporary operator of the metro , started planning the line during the late 1980s . the plans would take advantage of the gjøvik line 's right - of - way between storo and sinsen , while the section from storo to tåsen would have to be built in a tunnel . a projection for the line was presented in 1991 by oslo sporveier , where daily ridership was estimated to be 54 , 000 passengers . the plans included a possibility for the high - speed gardermoen line , that would be built to oslo airport , gardermoen , to have a stop at storo . this was later discarded when it was instead chosen to be built via lillestrøm . there were also ideas to run trains from the hoved line from lillestrøm to grefsen station via the alnabru – grefsen line , located adjacent to storo , that would allow the central parts of groruddalen to connect with the ring line and nordre aker . when the operating company ordered new t2000 trains for the holmenkoll line , the design allowed future versions to have dual current systems , to handle both the 750 volts on the metro network ( from a third rail and overhead wire ) , and the 15 kv 16 2 ⁄ 3 hz ac system of the main railways . this would allow the ring line to share the physical track with the gjøvik line on the section from storo to sinsen . the new were seen as a preparation for the ring line , and were optimised for higher speeds than the old stock , being capable of operating at 100 kilometres per hour ( 62 mph ) . at the same time , the sognsvann line was being upgraded to full metro standard , like the eastern part of the metro had , and would lose the overhead wires and get longer platforms . in 1992 , the tram division of oslo sporveier launched an alternative ring line that would have been built as a light rail , using in part the existing tramway . in the west , it would follow the sinsen line via sinsen to storo . a new line would have to be built from storo to tåsen . the line would then use the existing sognsvann line to majorstuen , where it would connect to the tramway and follow the frogner line into the city , via a new vika line through aker brygge . this alternative would cost nok 61 million to build , compared to nok 470 million estimated for the rapid transit solution . named the light rail ring ( norwegian : ) , it would have 38 stops instead of 16 stops , and a travel time of 34 minutes instead of 22 minutes . annual operating costs for the light rail solution would be nok 57 . 5 million , compared to 43 . 9 million for the rapid transit solution . between 1994 and 1998 , there was local political debate about how rikshospitalet , that was moving to gaustad , should be served by public transport . the state wanted to extend the ullevål hageby line of the tramway to the new hospital , while many local politicians wanted to use the rapid transit . since the ring line would increase traffic on the line , moving the line was considered to better serve the hospital . in 1998 , an agreement was reached whereby the light rail line would be built , and a new station for transfer from the metro would open at forskningsparken . a detailed proposal was presented by oslo sporveier in august 1996 . it became clear that berg would not be served by the ring line . many neighbours to the route of the sognsvann line complained about this proposal , stating that they had hoped that the section from majorstuen to berg would have been rebuilt as a tunnel . they also argued that it was irrational that the line was running at - grade in densely populated areas , while it would run in a tunnel through the then mostly unpopulated nydalen . to compensate , oslo sporveier stated that they would build noise screens along the line . also , the norwegian public roads administration protested to the plans , and stated that funding should be allocated to upgrading ring 3 to six lanes before public transport investments were made in the area . the city council voted in favour of building the ring line on 25 june 1997 , against the votes of the progress party . however , the decision did not include how the line would be financed , and the politicians stated that they were hoping that the state would use national road funds to finance the project . this was partially ensured in december , when a political agreement was reached for oslo package 2 , a financing plan for investments in public transport in oslo and akershus between 2002 and 2011 . in december 1999 , a disagreement arose between the ministry of transport and communications and the city ; the city would not except the government 's promise to finance part of the line . both minister of transport and communications , dag jostein from the christian democratic party and oslo city commissioner of transport and the environment , - jensen from the conservative party , agreed upon the distribution of funding from the city and state , and both wanted construction to start as soon as possible . the city council did not accept the guarantees from the state until march 2000 . construction started in june , with the agency for road and transport of the municipality responsible for construction . the city would pay nok 224 million , while the state would pay nok 673 million . the first section opened from ullevål stadion via nydalen to storo on 20 august 2003 , costing nok 590 million . with the opening , line 4 was extended from ullevål stadion to storo . nydalen had grown up as an urban redevelopment area after the local industry had been abandoned in the 1980s , where 14 , 800 jobs had been located by 2004 . on 20 august 2006 , the final section opened , from storo via sinsen to carl berners plass , with the whole project costing nok 1 , 348 million . a report published by the city in 2007 declared the line a success and stated that all goals for the line had been exceeded . a survey conducted by the city in 2003 and 2007 showed that the ring line had a significant impact on the use of public transport in the area . total public transport usage increased from 28 to 45 % ; use for commuting increased from 35 to 61 % . at the norwegian school of management ( bi ) , 85 % of the students used public transport . the ring line reduced the estimated number of daily car trips by 10 , 000 , and generated 11 , 000 more daily public transport trips . in 2007 , daily passenger numbers at the stations were for nydalen , 3630 for storo and 2300 at sinsen . the line allowed travel time from the nydalen and storo to the city centre to be halved , and travel time from nydalen to the city center is faster by metro than by taxi . route the 5 . 0 - kilometer ( 3 . 1 mi ) ring line branches off from the sognsvann line after ullevål stadion , just before berg . it immediately enters a tunnel that runs via nydalen to storo . the station at storo is just outside the entrance to the tunnel . from storo to sinsen , the tracks are laid parallel to the gjøvik line of the mainland railway . also the sinsen line of the oslo tramway and the ring 3 motorway follow the same corridor between the two stations . the section between ullevål stadion and storo is 3 . 3 kilometres ( 2 . 1 mi ) , while the section from storo to carl berners plass is 1 . 7 kilometres ( 1 . 1 mi ) . of these , 4 . 0 kilometres ( 2 . 5 mi ) are in tunnels . the nydalen district , formerly an industrial area , has since undergone urban redevelopment . the immediate vicinity of the station includes several large workplaces . in 2005 , bi , with 8000 students and faculty , moved into a new campus across the street from nydalen station . nydalen is the only underground station on the ring line . the escalators leading down to the platform features the tunnel of light , an artistic presentation of sound and colour around the passengers as they ascend from or to descend to the station . the artwork contains 1800 lights and 44 speakers . nydalen also serves as a bus hub . storo opened as a tram station as part of the grünerløkka – torshov line on 28 november 1902 . it is located about 200 meters from grefsen station of the gjøvik line . the norwegian national rail administration is planning to move the station platform so there can be direct transfer between nsb gjøvikbanen 's commuter rail services , and the metro . storo functions as a bus and tram hub ; it serves line 11 and 12 on the grünerløkka – and kjelsås line , and line 13 on the sinsen line . sinsen opened on 20 august 2006 , three years after the two other stations . the station is located close to , but not adjacent , to the tram stop on the sinsen line ( tram no . 17 ) . located at the interchange between ring 3 and trondheimsveien , it also serves as a bus hub . the løren line is a proposed connection which would connect the ring and grorud line . it would split from the ring line south of sinsen , and run part in tunnel and part at - grade until it connects to the grorud line west of . in the tunnel section the new station , løren , would be built . the day section would run parallel to part of the mainline alnabru – grefsen line . the line will allow metro trains to run directly from the grorud line to the ring line , and thus pass from east to west without passing through the packed common tunnel . it is part of the political compromise oslo package 3 , and estimated to be completed by 2017 . service when operating a full circle route , trains start through the common tunnel . if running clockwise , they pass through all the common stations ( tøyen , grønland , jernbanetorget , stortinget , nationaltheatret and majorstuen ) . they head north on the sognsvann line , stopping at blindern , forskningsparken and ullevål stadion . the ring line proper then splits off , and the trains serve nydalen , storo and sinsen , before carl berners plass on the grorud line . after that , the trains again enter the common tunnel at tøyen . lines 3 , 4 and 6 operate on the ring line , each with a 15 - minute headway . line 3 and 6 operates on the west side of the line , with line 3 terminating at storo and line 4 operating on the east side . between nydalen and storo , lines 4 and 6 swap numbers . from the city centre , line 4 comes from the lambertseter line , line 3 from the østensjø line and line 6 from the sognsvann line . after line 4 and 6 have run through the loop , they continue though the city again before heading to the terminal destination . travel time from nydalen and storo 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- , and holmenkoll line is available at majorstuen ; transfer to the , 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 grefsen station , that is close , but not adjacent , to storo . the oslo tramway can be reached from several stations . in the city centre , transfer to all lines is possible at jernbanetorget ; all lines but no . 12 can also be reached at either stortinget or nationaltheatret . lines 11 , 12 and 19 all terminate at majorstuen ; lines 17 and 18 run via forskningsparken ; lines 11 , 12 and 13 can be reached at storo ; and line 17 runs past carl berners plass .