Acciona Construction has completed the first of the 45 galleries connecting the two railway tunnels of the Follo Line project in Norway. These service galleries will be essential for carrying out maintenance work on the main tunnels and are a key element of the safety system. A total of 45 connecting galleries will be constructed, of which 33 will be 25 m long and the other twelve will be 12 m each. This work is expected to take 20 months.

The first gallery was excavated using the borehole expansion method, which breaks up the rock without using explosives, combined with traditional drilling. The hardest part of constructing these sections is coordinating the large number of tasks that have to be simultaneously carried out in the tunnels. The works on the connecting galleries have to be coordinated with the progress of the TBMs drilling the main tunnels in order to avoid damaging the tunnel rings or interfering with their work.

A total of 6 km of tunnel have already been drilled since the TBMs began to work in early September 2016. The four machines named Magda Flåtestad, Queen Eufemia, Queen Ellisiv and Anna fra Kloppa are working at full capacity. Magda Flåtestad, the fourth and last TBM at the Follo Line Project started its journey towards the city of Ski at the beginning of December.

The Follo Line project consists of a new 20km double-track line between Oslo’s Central Station and the intermodal station in Ski. The works are scheduled to be completed by December 2021. This is the first part of the inter-city development plan for south east Oslo.Click no/86 for tunnelbuilder archive. Visit http://www.acciona-construccion.com. 13/17.