The geometric guidance of preparing the foundation for the six elements of an immersed tunnel in the heart of the city of Oslo. Each tunnel element sits on approximately 40 gravel beds.
The installation of the gravel beds was carried out by the fall pipe pontoon “Scradeway” with an accuracy of + / – 20 mm at a maximum depth of 18.5 m. For the project, an accurate RTK-GPS system was developed based on a VRS (Virtual Reference Station) solution.

All elements are on schedule and within the specified accuracies posted. The tunnel connections to the existing road network is taken into use in mid-2010.