The Follo Line Project: a tunnel to Norway’s future

The Follo Line Project: a tunnel to Norway’s future

Oil wealth is very often associated with ostentatious displays of wealth – the purchase of football clubs and other trophy assets, for example. However, there is a different path, as exhibited by Norway. Since its oil find nearly 50 years ago, it has continuously taken a sustainable approach to investing with the long-term well-being of its citizens foremost in its decision making. The Follo Line project is the latest in a long line of these investments.

The Follo Line is the largest infrastructure project to date in Norway and the longest railway tunnel in the Nordic countries. When completed in December 2021, it will be the country’s first long twin tube rail tunnel and one of the first of its kind to be completed using boring machines. Now, almost two years after the beginning We recently took the time to look further into the development and what the long-term benefits that it will deliver for Norway’s citizens.

A high-speed, high-spec profile

The Follo Line project will add around 64 km of new railway tracks to Norway’s existing railway network. A new double track line from Oslo to the town of Ski, in the district of Follo. This line is being designed to cater for trains with speeds of up to 250 km/h, meaning that the typical journey time between Oslo and Ski will be reduced from its current 22 minutes to around 11 minutes.

Given that much of the railway line passes through Norway’s burgeoning capital city, Oslo, one might expect a good deal of disruption between now and the line’s delivery in 2012. Thankfully, however, the prepatory plans for the project drawn up in 2014/5 were comprehensive enough to ensure that even though it passes through the densely trafficked area around Oslo Central Station, the vast majority of the work will pass without disruption to the traffic to and from the station.

Specific engineering for a specific project

Engineering for a high-speed railway passing through busy city is complex enough in itself but further complication for the Follo Line project comes by virtue of the 20km tunnel, which will pass under the Ekeberg Hill in Oslo. Excavation works – perhaps the most significant part of the engineering challenge – are being performed by means of four hard rock shielded tunnel boring machines (TBM), which will bore approximately 18.5 km of the tunnel and drill and blast techniques will also be utilized for some of the tunnel work.

To provide some more context to the complexity of the task being undertaken, both the Follo Line and the relocated Østfold Line are located relatively closely to existing tunnels, caverns and sensitive installations. As such, particular attention must be paid to how the works affect the surrounding rock formations. In compliance with inter-European safety requirements for long tunnels, every 500 meters must be used as escape routes.

Partnership and a new form of contract for Norway

As mentioned at the outset of this article, Norway has always invested its oil wealth with the future prosperity of its citizens in mind. This means that even with a project like the Follo Line, the financial arrangements were carefully considered to maximize value for taxpayers. A new contract model was developed for the project – this is the first time that Norway has utilized EPC (engineering, procurement and construction) contracts for a general contractors, and on Signal contract for the frame agreement. The EPC is a well recognized contracting arrangement within the construction industry which has now been adapted for the Norwegian National Rail Administration.

The first of the project’s five EPC contracts was awarded to Italian firm Condotte (Societa’ Italiana per Condotte d’Acqua SpA) in February 2015. Its tender application was chosen for a combination of its financial and technical merits. Condotte already possesses extensive experience in tunnel works. A second EPC was awarded to OHL (Obrascón Huarte Lain) of Spain, tasked with delivering the EPC Ski section of the project. Considerable collaboration has also sprung from the project: the main part of the Follo Line has been contracted out to Agjv, a joint venture betwee n the Spanish company Acciona and Italy’s Ghella. The employment that all companies generate in the Oslo area will also have the positive side-effect  of upskilling young Norwegian engineers.

A sustainable solution

The Follo Line project will be a timely arrival to Norway’s railway network. The Østfold Line, which will be complementary to the Follo Line in serving Oslo’s commuter belt, has reached its capacity limit. In addition, the region served by the Follo Line is expected to see population growth of over 30% in the next ten years. As such, the line is a good example of sustainably planned infrastructure to cater for the realities of population growth.

Norway recently became the world’s first country to ban fuel powered cars, with 2025 being the date set to reach this target. The Follo Line must therefore offer an environmentally-friendly alternative and it promises to deliver on this requirement. During the construction phase, it will minimal impact on people, nature and the environment. Groundwater and Groundwater and properties that might be affected are being closely monitored.

Oslo’s built environment is also a concern – the Follo Line passes through some of Norway’s most significant cultural areas, including the Medieval Park, a site of great archaeological and historical significance. The Directorate for Cultural Heritage in Norway, Oslo Municipality and the Norwegian National Rail Administration have reached a joint solution for conservation measures regarding both the introduction of the new Follo Line and the new tracks for the Østfold Line through an area known as ‘Klypen,’ providing an opportunity to establish a park area almost twice the current size.


In summary, the Follo Line project will be impressive in more than one respect. In an age where public projects are often derided for being delivered significantly over-budget, outside the projected timeframe and even with lasting environmental side-effects, there’s reason to believe that the Follo Line Project – with an estimated life of over 100 years – will have a lasting positive legacy on Norway’s transport infrastructure and its environment.



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