The tunnel was previously also known as the Mountain Line (Шаблон:Lang) and the Oslo Tunnel (Шаблон:Lang). The name Fjellinjen was since taken over by the company responsible for charging toll fees on the urban toll ring in Oslo. The tunnel changed its official name from the Oslo Tunnel to the Festning Tunnel in 1998 to avoid confusion with the railway tunnel with the same name. In 2008 and 2009, the electrical installation in the tunnel is being upgraded, financed through toll fees, costing Шаблон:NOK.[1]
In the west, the tunnel connects to Dronning Mauds gate with a cloverleaf intersection, and also has the intersection prepared for a future Slottspark Tunnel. In the east, it connects to Nylandsveien and Ring 1 at Bjørvika. In 2012, the Bjørvika Tunnel will be constructed below Bjørvika, and the new tunnel will connect directly with the Festning Tunnel.[2]
The tunnel was built to remove traffic from The City Hall Square, the square in front of the Oslo City Hall, and allow better access to the waterfront from the city. After the tunnel opened in January 1990, cars remained on The City Hall Square until 1994. In 1995, the Vika Line of the Oslo Tramway was built across the square.[3]
