Norway Constructs World’s Deepest Underwater Road Tunnel to Reduce Coastal Journey from 21 Hours to 10

Norway is drilling the 27km Rogfast tunnel 392m under the Boknafjorden fjord, aiming to cut E39 travel time from 21 hours to 10 by 2033.

By: AXL Media

Published: Apr 24, 2026, 4:47 PM EDT

Source: The information in this article was sourced from Clickpetroleoegas

Overcoming the Natural Barriers of the Norwegian Fjords

For decades, the spectacular fjords of Norway’s west coast have served as both a tourist attraction and a massive logistical hurdle. Currently, traveling the 1,090-kilometer stretch of the E39 highway between Trondheim and Kristiansand requires 21 hours of driving and seven separate ferry crossings. These maritime links are often subject to delays or cancellations during the region’s frequent storms. The Rogfast project aims to eliminate these bottlenecks by creating a continuous land connection through the rock beneath the Boknafjorden fjord.

Breaking Records in Subterranean Engineering

The Rogfast tunnel is set to become the "king" of Norwegian tunnels, surpassing the current record-holders in both length and depth. At 27 kilometers, it will be longer than the Laerdal Tunnel (24.5 km) and reach a depth of 392 meters below sea level—over 100 meters deeper than the Ryfast tunnel. This depth presents unique challenges for engineers, who must account for extreme hydrostatic pressure and the potential for water seepage through geological fractures. The project utilizes four lanes—two in each direction—to ensure high-capacity traffic flow between Stavanger, Haugesund, and Bergen.

The World’s Deepest Underground Roundabout

A highlight of the project’s technical innovation is the inclusion of an underground interchange connecting to the island of Kvitsøy. This feature includes an unprecedented road roundabout situated 250 meters below the surface. This "underground hub" allows for local connectivity without compromising the main transit route, adding a layer of complexity to the ventilation and safety systems. Engineers must ensure that vehicle emissions are continuously and effectively extracted from the 27-kilometer stretch, a task made more difficult by the tunnel's extreme depth.