Follo Line
The Follo Line () is a high-speed railway between Oslo and Ski, Norway. The line runs parallel to the Østfold Line, and is dimensioned for . Most of the line, , runs in a twin-tube tunnel named the Blix Tunnel, which is the longest railway tunnel in the country. Construction started in 2015, and the line opened in 2022. The Follo Line increased capacity from twelve to forty trains per hour along the South Corridor, and allows express and regional trains to decrease travel time from Ski to Oslo from 22 to 11 minutes. The line was projected to cost over 26 billion Norwegian kroner (NOK) in 2014, but the final cost became 36.8 billion NOK when it was completed. The project was a continuation of the Norwegian National Rail Administration's (now Bane NOR) plan to build four tracks along the three main corridors out of Oslo; the Gardermoen Line was completed in 1998, and the Asker Line was completed in 2011. Between 1989 and 1996, the Østfold Line south of Ski to Moss was upgraded to double track and higher speeds. To take full advantage of this and allow the rest of the Østfold Line to be upgraded for high speeds, it was necessary to increase capacity through the bottleneck from Oslo to Ski. The Follo Line is hoped to increase rush hour rail ridership by 63%, and increased freight on rail is hoped to remove 750 trucks daily from roads like E6 and E18. History Background The first railway in the Follo district was the Østfold Line of the Norwegian State Railways (NSB) that opened on 2 January 1879, between Oslo East Station and Halden. Later the same year, the line was extended to the Swedish border, where it connected to the Norway/Vänern Line. The importance of Ski Station increased on 24 November 1882, when it became the station where the Eastern Østfold Line split, and went via Inner Østfold to Sarpsborg, where the two lines reconnected. Electrification of the section from Oslo to Kolbotn was completed on 18 January 1937, and the section to Ski finished in 1939; the whole Østfold line was completed in 1940. Between 1924 and 1939, NSB built double track along the route between Ski and Oslo. From 1989 to 1996, NSB upgraded the track to double track from Ski to Sandbuka, just north of Moss. This section is capable of speeds of , however the maximum is due to short distances between stops and limitations of the rolling stock. In 1992, the Norwegian Parliament decided to build the first high-speed railway in Norway, from Oslo via the new Oslo Airport, Gardermoen to Eidsvoll. This line would run parallel to the Hoved Line, increasing the speed and capacity along the route. Fast express and regional trains could run along the new section, while slower commuter trains used the old tracks and could make many stops without disturbing other traffic. Projects were launched during the 1990s to create similar high-speed bypasses from Oslo to