The ACCIONA Ghella Joint Venture (AGJV)has now completed 66% of the tunneling for the construction of the twin 19.5-kilometre high-speed tunnel between Oslo and Ski, in Norway.
The four tunnel boring machines (TBMs), which are working simultaneously to construct the twin rail tunnels; soon will get the 24,000 meters excavated, two-thirds of the final goal of the Follo Line´s project.
They are 150 meters long and weigh 2,400 tons. The first TBM, Eufemia, started to work in September 2016 and it has excavated almost 7 kilometers so far, 77 percent of her way to Oslo.
Ellisiv, another of the four TBMs, is following only 60 meters behind.The average progress is 100 meters a week per machine, getting ahead of schedule, and it is now exciting which TBM will be the first one to reach Oslo.
On the other hand, the TBMs Anna and Magda are working continuously towards Ski, and they are also on schedule. They have excavated respectively 5,2 (57 %) and 5 kilometres (55 %).
In addition to the progress in the tunneling works, the manufacture of ring segments also advances. The number of produced tunnelrings in the precast factory is approximately 15,400. The total number of rings to be produced is around 20,236, that means approximately the 75% of the total production.
One of the biggest challenges is the hardness of the Norwegian rock, that difficult the excavation, as well as the weakness of other areas.
The Follo Line is the largest transport initiative ever undertaken in Norway. It is part of the interurban development plan for south-eastern Oslo, which aims to improve and promote the country’s transport infrastructure. It includes construction of 22 km of rail line between Oslo and the new train station in Ski and is scheduled for completion by December 2021.