Science

The world’s longest and deepest underwater mega-construction project is now underway and is being developed 24 hours a day

The record setting Rogfast project aims to connect islands and mainland Norway nearly 1,300 feet below the sea, with crews working nonstop until its planned 2031 opening

Miguel Varela

Update: Nov 21st, 2025 11:56 EST

Norway is taking on one of the most ambitious construction projects in its history. The country is building Rogfast, which is on track to become the longest and deepest underwater road tunnel on the planet. The tunnel will run 16.6 miles with a low point of about 1,286 feet below sea level as it cuts beneath the Boknafjord to link Randaberg and Bokn. The new connection will eliminate the need for ferries and significantly improve travel between Norway’s islands and mainland Europe.

Part of a massive coastal highway plan

Rogfast is a key piece of the future E39 highway, a 684 mile strategic route designed to connect southern and northern Norway without maritime interruptions. Within the broader plan, Rogfast is considered the most technically demanding section. The project will cut current travel times to only 35 minutes thanks to two single direction tunnel tubes.

Costs, delays and a nonstop construction schedule

The project is expected to cost more than 20.6 billion Norwegian kroner, roughly 2.01 billion dollars. Although construction was paused in 2019 due to cost overruns, work resumed in 2021 and has continued without interruption. Crews are still operating day and night with the goal of opening the tunnel to traffic in 2031. Full service may extend into 2033.

Digging through solid rock

As expected, the engineering challenges are immense. Excavation moves through hard gneiss and granite, along with fractured zones and softer materials that require constant reinforcement to prevent leaks and collapses. Crews are using drill and blast methods. Hundreds of robotic drilling rigs are loaded with explosives each day. After each blast, ventilation systems clear the gases before debris is removed and the cycle begins again.

A giant underground interchange

The project also includes a massive underground interchange located about 820 feet down, which will link to the island of Kvitsøy. Engineers are adding a complex network of cross passages spaced every 820 feet, along with ventilation systems designed to manage air quality and smoke at extreme depths. By the time work is complete, crews are expected to remove roughly 353 million cubic feet of rock. Much of it is being reused for other construction projects and coastal land reclamation.

High tech construction in real time

One of the most innovative aspects of Rogfast is its digital control system. The Tunneling Intelligence platform, developed by Epiroc, uses 3D monitoring to track machine positions, anticipate safety risks and update excavation plans in real time. The platform also centralizes alerts, emergency protocols and operational data, establishing Rogfast as a global leader in digital infrastructure management.