Norway's largest transport infrastructure project took over two decades from proposal to completion, and the result was as dramatic as it was delayed. The Follobanen, or Follo Line, is a 22-kilometre high-speed railway connecting Oslo S to Ski. Its centrepiece is the 19-kilometre Blixtunnelen, the longest railway tunnel in the Nordic countries. The tunnel is named after Peter Andreas Blix, the architect who designed the original Østfoldbanen railway in the 1870s.
The idea of a new high-speed rail link south of Oslo was first proposed in 1995. Construction finally began in 2015 with four massive tunnel boring machines working from both ends. Designed for speeds up to 250 km/h, the new line would cut the Oslo to Ski journey from 22 minutes to 11, and increase capacity on the southern rail corridor from 12 to 40 trains per hour.
Problems started early. In July 2017, two quick clay landslides hit the construction site at Ski station within eight days of each other. Engineers had been warned about the unstable ground, and an independent reviewer had recommended stronger stabilization measures. The warnings were not fully acted on. The collapses caused major delays and cost overruns. Bane NOR later tried to claim 88.8 million kroner from insurers but lost the case in Oslo District Court and was ordered to pay 5.5 million in the opposing side's legal costs.
Along the tunnel route, hundreds of private geothermal energy wells had been drilled down from the surface into the bedrock, particularly on the Nordstrandsplatået and at Langhus. Over 300 wells were registered along the route. As the tunnel boring machines cut through the rock, they physically severed approximately 35 to 40 of these wells, leaving homeowners without functioning heat pump systems. Bane NOR acknowledged that some wells simply could not be saved.
The line finally opened on 12 December 2022. Within days, it was shut down again. A faulty electrical contact wire system made the tunnel unsafe for train operations. It did not reopen until 5 March 2023, nearly three months later. The overhead power lines had to be replaced again in 2024, and contaminated water dripping inside the tunnel created additional maintenance challenges.
The budget tells its own story. Early estimates put the project at around 14 billion kroner. The approved budget in 2014 was 26.5 billion. The final cost came in at approximately 36.8 billion, more than double the original estimate. In December 2025, two project leaders, one from Bane NOR and one from a contractor, were charged with corruption for billing 2.6 million kroner of private home renovations to the Follo Line project. Both admitted guilt.
The idea of a new high-speed rail link south of Oslo was first proposed in 1995. Construction finally began in 2015 with four massive tunnel boring machines working from both ends. Designed for speeds up to 250 km/h, the new line would cut the Oslo to Ski journey from 22 minutes to 11, and increase capacity on the southern rail corridor from 12 to 40 trains per hour.
Problems started early. In July 2017, two quick clay landslides hit the construction site at Ski station within eight days of each other. Engineers had been warned about the unstable ground, and an independent reviewer had recommended stronger stabilization measures. The warnings were not fully acted on. The collapses caused major delays and cost overruns. Bane NOR later tried to claim 88.8 million kroner from insurers but lost the case in Oslo District Court and was ordered to pay 5.5 million in the opposing side's legal costs.
Along the tunnel route, hundreds of private geothermal energy wells had been drilled down from the surface into the bedrock, particularly on the Nordstrandsplatået and at Langhus. Over 300 wells were registered along the route. As the tunnel boring machines cut through the rock, they physically severed approximately 35 to 40 of these wells, leaving homeowners without functioning heat pump systems. Bane NOR acknowledged that some wells simply could not be saved.
The line finally opened on 12 December 2022. Within days, it was shut down again. A faulty electrical contact wire system made the tunnel unsafe for train operations. It did not reopen until 5 March 2023, nearly three months later. The overhead power lines had to be replaced again in 2024, and contaminated water dripping inside the tunnel created additional maintenance challenges.
The budget tells its own story. Early estimates put the project at around 14 billion kroner. The approved budget in 2014 was 26.5 billion. The final cost came in at approximately 36.8 billion, more than double the original estimate. In December 2025, two project leaders, one from Bane NOR and one from a contractor, were charged with corruption for billing 2.6 million kroner of private home renovations to the Follo Line project. Both admitted guilt.
