Frøen Station was rebuilt so only the trains on the Holmenkollen Line would stop there, while Nordberg Station was closed. All the stations, except Ullevål stadion, were built in the same architectural style. They are constructed in concrete with steel columns and wooden sheds and fences. All platforms have a shed; Ullevål stadion has a larger weather cover and has a design inspired by football. The upgrade also included the installation of third-rail from Majorstuen to Stortinget in the Common Tunnel. From 10 January 1993, the Sognsvann Line re-open, and from 4 April, the line started operating through the Common Tunnel and connected to the Lambertseter Line. The new service became operated with T1000 rolling stock.