Norway is pushing the boundaries of modern engineering with Rogfast, a massive infrastructure project set to become the world’s longest and deepest undersea road tunnel. Currently under construction on the country’s west coast, the 27-kilometer (17-mile) tunnel will eventually plunge 392 meters (1,286 feet) below sea level—deeper than any existing road tunnel of its kind.
Rogfast is a key part of Norway’s long-term plan to transform its coastal E39 highway into a fully ferry-free route. By linking the Stavanger and Haugesund regions, the tunnel is expected to cut travel time between major west-coast cities by around 40 minutes and drastically improve the daily commute for thousands of residents.
Construction of the tunnel began in 2018 but was halted the following year due to cost overruns, prompting a review and restructuring. Work resumed in late 2021, and the project is now scheduled for completion in 2033 at an estimated cost of 25 billion Norwegian kroner (around $2.4 billion).
Designed as two parallel tubes with two lanes each, Rogfast will feature a rare engineering centerpiece: a giant double roundabout located 260 meters underground, linking a side tunnel to the small island of Kvitsøy. The project involves extreme technical precision—construction teams are drilling from both ends and must meet in the middle with a margin of error of just 5 centimeters.
Advanced laser scanning and real-time geological data are being used to achieve this accuracy. According to project engineers, even minor deviations can result in huge extra costs and emissions due to additional excavation and backfilling.
Working at such great depth also brings significant challenges, including saltwater leakage and air quality concerns. Engineers are refining grouting methods to seal the rock and installing a sophisticated ventilation system that includes jet fans and vertical shafts. Sensors, cameras, and radar will monitor the tunnel once operational.
Rogfast is part of a much larger transformation of Norway’s rugged western coastline, where fjords and mountains have long made travel slow and dependent on ferries. By replacing these crossings with tunnels and bridges, the country aims to halve the 21-hour travel time along the E39 highway by 2050.
Although the project could eventually reduce ferry-related jobs, Norwegian officials emphasize its long-term economic and social benefits—from improving access to education and healthcare to boosting the region’s seafood industry by lowering logistics costs.
When complete, Rogfast will take its place among the world’s most ambitious infrastructure feats—surpassing the depth of Japan’s Seikan Tunnel and the Channel Tunnel between the UK and France, despite being shorter in overall length. Its construction marks an impressive step forward in undersea engineering and a major investment in Norway’s future connectivity.
