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ACCIONA presents latest advances in Follo Line project at World Tunnel Congress in Norway


More than 12 km of tunnel have now been bored, equivalent to 30% of the total.

Four tunnel boring machines are working simultaneously to excavate what will be Scandinavia’s longest railway tunnel. 

ACCIONA Construction has taken part in the World Tunnel Congress, the most important event for the sector internationally, which this year was held in the Norwegian city of Bergen.

Fernando Vara, head of the Follo Line project for the ACCIONA Ghella Joint Venture (AGJV), gave a talk at the event about the technical aspects and specific design and construction characteristics of this globally pioneering project.

This is the first time that a project of these characteristics, using four tunnel boring machines (TBM) starting from a single point, has taken place, presenting enormous organisational and logistical challenges on the surface.

During his presentation, Vara showed various videos of the construction process and the current level of progress of the works. Since work began in September 2016, more than 12 km of tunnel have been drilled, equivalent to 30% of the total. 

Four tunnel boring machines are currently working simultaneously to excavate what will be Scandinavia’s longest railway tunnel. The twin-tube tunnel will be 19.5 km long, connecting the city of Oslo with the town of Ski in just 11 minutes.

Each of the four tunnel boring machines being used on the project will drill more than nine kilometres of tunnel. They have been especially designed for the hard Norwegian rock and are operating as planned in terms of technology, quality and propulsion.  Each one is 150 m long and weighs 2,400 tons, with a cutting diameter of 9.96 metres and capable of drilling an average of 12-15 metres per day.

To guarantee the integrity of the tunnel, it is simultaneously lined with segmented concrete rings, constructed as the TBMs progressively excavate the tunnel. Around 140,000 segments will be used in the tunnel, manufactured by a special plant set up close to tunnels in Åsland. The TBMs are being used in conjunction with traditional drilling and blasting methods.

A group of international visitors and members of the press were invited to visit the project works on 9 June, which included part of the excavated tunnel, to coincide with the World Tunnel Congress in Norway.

The Follo Line is the largest transport project ever undertaken in Norway and is using the most innovative construction methods. It is part of the wider inter-city development plan for south-east Oslo, which seeks to improve and promote the country’s transport infrastructure. It includes construction of 22 km of railway line between Oslo and the new train station in Ski. 

The works being undertaken by AGJV for the Norwegian National Rail Administration involves a team of 800 employees from 27 countries.

The World Tunnel Congress, organised by the International Tunnelling and Underground Space Association (ITA), is the most prestigious event in the tunnelling sector. The 2017 edition, held in Bergen from 9 to 15 June and opened by the Crown Prince of Norway, Haakon Magnus, was attended by more than 1,500 delegates.

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