Norway has officially begun assembling what will become the world’s longest and deepest undersea road tunnel, a record-breaking engineering project designed to transform travel along the country’s rugged western coast. Known as Rogfast, the 27-kilometer tunnel will plunge 392 meters below sea level and eventually replace ferry crossings between major coastal regions.
Rogfast, short for “Rogaland fastforbindelse,” is part of Norway’s long-term plan to create a ferry-free highway along the E39 route, as reported by CNN. The tunnel will connect the Stavanger and Haugesund regions and shave roughly 40 minutes off travel time between Bergen and Stavanger, two of the nation’s most important cities. Construction initially began in 2018 but was paused in 2019 due to major cost concerns. After a full restructuring, work resumed in late 2021. The project is now expected to finish in 2033 with a total budget of about $2.4 billion.
According to Skanska project manager Anne Brit Moen, Rogfast will significantly improve regional mobility and reliability, helping commuters and businesses that currently depend on ferries. The tunnel’s design includes two parallel tubes, each carrying two lanes of traffic, and a rare underground double roundabout roughly halfway through. That junction will lead to a connection tunnel serving the island of Kvitsøy, Norway’s smallest municipality.
Building such an immense structure under the seabed demands extreme precision. Engineers are currently constructing the tunnel from both ends with the goal of the two excavation teams meeting in the middle with a deviation of no more than five centimeters. To achieve this accuracy, crews use high-tech laser scanners capable of collecting millions of data points per second to create a digital twin of the tunnel as it is carved from the rock.
But the project has not been without challenges. As Moen explains, sealing the rock has proven difficult due to saltwater leaks encountered at depths of around 300 meters. Since the tunnel will descend even deeper, engineers are testing improved grouting techniques to maintain safe working conditions. The completed tunnel will feature an advanced ventilation system, including jet fans and vertical shafts, and real-time monitoring with radar and cameras to detect incidents and maintain airflow.
Rogfast forms a key part of Norway’s broader effort to overhaul the entire 1,100-kilometer E39 coastal highway. That plan aims to eliminate all seven ferry crossings along the route by 2050, cutting the full journey time in half. While ferries will eventually be phased out, officials say the tunnel will ultimately strengthen the regional economy, improve access to education and jobs, and support industries such as seafood logistics by reducing transport times.
When completed, Rogfast will stand deeper than Japan’s Seikan Tunnel and the Channel Tunnel between England and France, setting a new global benchmark for undersea road construction.
