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Follo Line makes final double tunnel breakthrough

follobanen gjennomslag

The excavation of the longest rail tunnel in the Nordic countries was completed earlier this week, the Norwegian national rail administration, Bane Nor, has announced.

The last two of the Follo Line’s four 150m tunnel boring machines (TBMs) broke through the mountain at Kvakestad in Ski on Tuesday completing the drilling for the longest railway tunnel in the region.

The 10m diameter TBMs had completed excavation of the 9km tunnels for the Follo Line, which will provide a high speed rail service between Oslo and the smaller town Ski.

The first double breakthrough was in September 2018 when two TBMs heading northbound towards Oslo completed their drives.

Bane Nor deputy director infrastructure construction Birger Steffensen said: “Bane Nor as the builder is pleased that tunnel drilling has been completed on time. This is a good result. Bane Nor looks forward to halving the travel time between Oslo and Ski with the new Follo Line. Railway investment is important for travellers and for growth and development in the Oslo and Follo regions.”

Around 350 invited guests and employees were present when the last TBMs broke out into a mountain cutting just outside Ski Centre.

20km of the 22km long Follo Line will be tunnels, with some parts constructed using blasting and splitting rock and the rest driven by TBM.

Speaking at the breakthrough event on Tuesday, Follo Line project director Per David Borenstein said: “The tunnel production we celebrate completion of today is the longest stretch of the Follo Line. The project has some challenges, but the tunnel drive has been carried out as planned. As a builder, Bane Nor is very pleased with the work that has been done and the good cooperation between turnkey contractor Acciona Ghella and Bane Nor.”

follobanen gjennomslag nicolas tourrenc 780

Follo Line breakthrough

Source: Nicolas Tourrenc

Acciona Ghella project director Fernando Vara added: “We have encountered hard, Norwegian mountains and challenging ground conditions, but thanks to our expertise and good work, we have mastered this. We are pleased to have handled such a large and demanding TBM project. Now we are moving into a new phase, and we are confident that we will do a good job also in view of the remaining work on rail technology.”

Bane Nor chose to use TBMs as the main method for driving the Follo Line’s longest tunnel (Blix tunnel).

Bane Nor project manager for tunnel production Anne Kathrine Kalager said: “We considered different methods, but understood early on that tunnel drilling is a good choice. With this project we have shown that tunnel driving with tunnel drilling machines can be a very good alternative to conventional blasting when building long tunnels in Norway, emphasizes parts of the tunnel drilling machines, each of 2,400t, are now transported back to Herrenknecht in Germany, where they were specially made for Bane Nor.”

The TBMs were started by prime minister Erna Solberg and then minister of transport and communications, Ketil Solvik-Olsen on 5 September 2016.

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