The Oslo Tunnel is a 3,632-metre (2.257 mi), double-track, railway tunnel which runs between Olav Kyrres plass and Oslo Central Station (Oslo S) in Oslo, Norway. The tunnel constitutes the easternmost section of the Drammen Line and runs below the central business district of Oslo. It features the four-track Nationaltheatret Station, Norway's second-busiest railway station, where the Oslo Tunnels lies directly beneath the Common Tunnel of the Oslo Metro. At Frogner, the Elisenberg Station was built, but has never been used. The tunnel is the busiest section of railway line in Norway and serves all west-bound trains from Oslo, including many services of the Oslo Commuter Rail and the Airport Express Train.

Oslo Central Station is the main railway station in Oslo, and the largest railway station within the entire Norwegian railway system. It connects with Jernbanetorget station, which is served by trams and the Oslo Metro. It's the terminus of Drammen Line, Gardermoen Line, Gjøvik Line, Hoved Line, Østfold Line and Follo Line. It serves express, regional and local rail services by four companies. The railway station is operated by Bane NOR while its real estate subsidiary, Bane NOR Eiendom owns the station, and was opened in 1980.