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 Bibliography Oslo Metro lines Railway lines opened in 1957 1957 establishments in Norway