The Follow Line project consisted of the construction of two twin tunnels between the cities of Oslo and Ski. Their execution meant an improvement for the country as they not only optimised the communication routes but also reduced the pollution of the area.

To this day, they are the longest railway tunnels in Norway with 19.5 km each. Caldibe's participation in this project was based on the manufacture of the formwork used for the lining of the connection galleries between these tunnels, including the carrier for moving them.