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 and 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 construction of tramways were halted. tram on the Lambertseter Line between Manglerud and Høyenhall in 1963 Planning of the metro commenced in 1946. A committee was appointed, who quickly that a tramway would be insufficient to handle the necessary traffic. An overground system was ruled out because of the increased estimates in traffic and an underground route was instead pursued. This part of the line would need to handle a traffic of 20,000 passengers per hour. Following the 1948 merger of the municipalities of Oslo and
Aker, it was decided that the
Nordstrand area in the former Aker would be opened to large-scale residential construction. Instrumental in the change of magnitude was the change of was a shift in the zoning planning. There was a large housing shortage in Oslo and the region was experiencing rapid population growth. The solution was to build a series of
commuter towns in Aker, which would be the basis for the traffic on the metro. Plans for both a metro and new housing were substantiated in a 1950 municipal plan. tram at
Munkelia Station on 17 May 1966, the last day with tram services The basics for the metro were established in 1951, with a common segment through Enerhaugen with a terminus at
Grønlands torg, to avoid having to cross
Akerselva. The plans were made such that in the future the line could be extended to connect to
Holmenkolbanen's western underground line at
Nationaltheatret. Four branches would be built, including the Grorud Line; the existing Østensjø Line would be converted to metro. The Lambertseter Line was politically approved on 3 April 1952 and the full four-line network was approved on 9 December 1954. The latter included moving the terminus to
Jernbanetorget. Investments were estimated at 221 million
Norwegian krone, including rolling stock. The Lambertseter Line was given a new route west of Ryen, and would connect to the
Østensjø Line at Bryn. These plans were passed by the city council on 9 December 1954, and also included the construction of the
Grorud Line and an extension of the Østensjø Line from
Oppsal to
Bøler. In February 1956, it was also decided that the Lambertseter Line would be expanded to
Bergkrystallen. From Helsfyr the line continued to the city center via the
Vålerenga Line and the
Gamlebyen Line. The last trams operated during the night between 17 and 18 May 1966, in preparation for the conversion to metro. The line was disconnected with the tramway at Høyenhall and instead to the new metro line that leads to the Common Tunnel. At Bergkrystallen the loop was removed and the tracks rebuilt. All the platforms had in due time been rebuilt to the platform height used by the metro. train at
Bergkrystallen in 1971 On 9 January 1977, the city center service was extended to
Sentrum. However, this station was closed from 20 March 1983 to 7 March 1987, and reopened as Stortinget. During the last years of the 1980s the barres and payment stalls were removed and replaced with a
proof-of-payment system. This unstaffing of the station allowed for a significant cut in operating costs. On 4 April 1993 the
Sognsvann Line was converted to a metro line and it was linked with the Lambertseter Line and Line 4. With the delivery of
T2000 trains, the
Holmenkollen Line and Line 1 was also routed to the Lambertseter Line, although outside of rush hour Line 1 did not run past Helsfyr. trains meeting near Brynsenteret in 2006 This was changed from 12 April 2003, when Line 4 was linked with the
Kolsås Line, From 20 August 2006 this was changed and Line 4 connected instead with the Ring Line. An express bus line, Line 4E, was also established to relieve pressure on the metro. When Line 1 resumed, it was instead linked with the
Furuset Line until being reconnected to the Lambertseter line on 3 April 2016. The Lambertseter Line between Brynseng and Ryen received a major upgrade in 2010. The oldest tracks on the line were from 1943 and were in poor condition. Their poor quality had among other issues caused the speed between Høyenhall and Manglerud to be reduced to . Three stations, Høyenhall, Manglerud and Ryen, received upgrades, including new sheds, new lighting and better
accessibility. The work involved the line being closed for almost two months. A second round of upgrades were carried out from 8 April to 9 September 2013, this time on the section from Ryen to Bergkrystallen. All stations except Bergkrystallen were upgrades, receiving new sheds, lighting, platform decks and improved accessibility. The ballast had become clogged up, hindering proper drainage. Tracks and ballast were replaced, allowing the temporary speed limit of to be abolished. In addition, two bridges and two culverts were renovated. The project cost 160 million
Norwegian krone. ==References==