Norway Proposes World's First Underwater Floating Tunnel

In order to cut down on travel time along the west coast of Norway, the Norwegian Public Roads Administration (NPRA) has proposed the design of floating tunnels to run beneath fjords that would normally be crossed by ferry or circumnavigated. The west coast of Norway contains 1190 fjords. The scenic drive from Kristiansand in the south up to Trondheim in the north takes 21 hours and seven ferry crossings. The tunnel system would take a fraction of that time but could cost approximately 25 million dollars.

These tunnels would float approximately 66 feet beneath the surface of the Norwegian Sea. The curved concrete tunnels would be kept afloat by large pontoons positioned at intervals along the length of the tunnel. By having the tunnel suspended below the surface, ferries will be able to pass above the tunnel and between the pontoons. The tunnel will seem like any other to drivers inside. On either side, the tunnel will enter bedrock and slope up to the entrance and exit. 

Other options are also being considered for crossing the fjords. Combining an underwater tunnel with a land bridge extending part way across the fjord is one option and would resemble the Oresund connecting Denmark and Sweden. A second option is a suspension bridge spanning 12,139 feet, double the current world record length with towers 492 feet higher than the Eiffel Tower (1,476 feet).

It is estimated that the fjord crossings could be completed by 2035.