During winter NSB had large costs keeping the line snow-free.
Large diesel-electric snowploughs were stationed at Finse, and tens of kilometers of snow sheds were built on the most vulnerable parts.
Especially the 22 kilometres (14 mi) part between Finse Station and Hallingskeid was a drain on resources, and heavy snowfall and drifts regularly closed the entire line.
A solution was proposed by NSB's director Robert Nordén in 1984, involving construction of a 10.5 kilometres (6.5 mi) tunnel between the two stations.

In 1989 the Parliament of Norway approved the plans, including the upgrade of part of the line east of Finse.
In total NOK 750 million was invested in rebuilding 32 kilometres (20 mi) of line, shortening it by 4.5 kilometres (2.8 mi).
At the same time the permitted speed could be increased from 70 kilometres per hour (43 mph) to 170 kilometres per hour (110 mph).
The tunnel opened on 16 June 1992 while the rest of the upgrades opened in five steps between 1995 and 1998.
The highest point on the line, previously at 1,301 metres (4,268 ft), became 1,237 metres (4,058 ft)—located inside the tunnel.
After the tunnel opened, the Finse snow removal facility was closed.
During winter NSB had large costs keeping the line snow-free. Large diesel-electric snowploughs were stationed at Finse, and tens of kilometers of snow sheds were built on the most vulnerable parts. Especially the 22 kilometres (14 mi) part between Finse Station and Hallingskeid was a drain on resources, and heavy snowfall and drifts regularly closed the entire line. A solution was proposed by NSB's director Robert Nordén in 1984, involving construction of a 10.5 kilometres (6.5 mi) tunnel between the two stations.
In 1989 the Parliament of Norway approved the plans, including the upgrade of part of the line east of Finse. In total NOK 750 million was invested in rebuilding 32 kilometres (20 mi) of line, shortening it by 4.5 kilometres (2.8 mi). At the same time the permitted speed could be increased from 70 kilometres per hour (43 mph) to 170 kilometres per hour (110 mph). The tunnel opened on 16 June 1992 while the rest of the upgrades opened in five steps between 1995 and 1998. The highest point on the line, previously at 1,301 metres (4,268 ft), became 1,237 metres (4,058 ft)—located inside the tunnel. After the tunnel opened, the Finse snow removal facility was closed.
Bergen Line