The Rogfast subsea road project: Engineering geological challenges and technical-contractual mitigation measures
The Rogfast E39 coastal highway project involves the construction of a 26.7 km long and almost 400 m deep twin-tube subsea tunnel across the Kvitsøy- and Boknafjord and a tunnel up to the island of Kvitsøy. Some special features of the project are a large roundabout intersection area, and tunnels, shafts and rock caverns that will be used for the purpose of ventilation. Some of the geological hazards at this project involve rock mass collapse, squeezing and sudden large water inflow at high pressure, which in the worst case can lead to inundation of the tunnel. Norconsult is the planning consultant for the Norwegian Public Roads Administration concerning the preparation of the detailed design and tender documents. This article describes some of the expected engineering geological challenges and planned technical and contractual mitigation measures in order to ensure the successful completion of the project.