Brenner Base Tunnel and Fehmarnbelt Fixed Link: Two Tunnels to Unite Europe

In the heart of the Alps, beneath the invisible line that divides Italy and Austria, mechanical tunnel boring machines have bore tunnels more than a thousand meters deep. Thousands of kilometers farther north, beneath the cold waters of the Baltic Sea, the journey of the TBMs takes place under the seabed. Their mission is to construct the two massive tunnels that will reshape European mobility: the Brenner Base Tunnel and the Fehmarnbelt Fixed Link.

Two major transport infrastructures that are reshaping the continent’s mobility and shortening distances. These are two symbolic projects of the TEN-T corridors, the European Union’s strategy to connect countries through sustainable, efficient, and integrated transport.

The Brenner Pass has always been the physical and symbolic border between the Mediterranean world and Central Europe. Where the Alpine range narrows between Bolzano and Innsbruck, the A22 highway is currently the only thoroughfare for crossing from Italy into Austria. Today, over 2,200 trucks cross it daily, leading to significant impacts on traffic, noise, and air quality in the Alpine valleys.

This is why the Brenner Base Tunnel (BBT) project was conceived – what will become, once completed – the longest railway tunnel in the world. The Webuild Group is also involved in its construction, on behalf of BBT SE, working on 50 of the total 64 km of tunnel, divided into four lots, two of which are already complete.

The tunnel will connect Fortezza (Italy) to Innsbruck (Austria) with a high-capacity line. This will allow passenger trains to travel up to 250 km/h and freight trains up to 120 km/h, bypassing the steep gradients of the existing historic railway, which is over 150 years old.

Its construction sites are a mosaic of advanced technologies: tunnel boring machines (TBMs) over 100 meters long, underground ventilation systems, a pilot tunnel already completed for geological verification, and excavations conducted using freezing techniques—in the Italian section beneath the Isarco River—employing a highly sophisticated method that freezes the ground using liquid nitrogen to ensure safe tunneling.

The Brenner Tunnel is a unique work, then, representing the backbone of the TEN-T Scandinavian-Mediterranean corridor designed by the European Union.

Farther north, where Denmark meets Germany, the sea has always separated peoples and trade routes. The island of Fehmarn in Germany and that of Lolland in Denmark are currently connected by ferries transporting thousands of people and heavy vehicles each day. But since 2007, following the signing of a bilateral agreement, a project was launched to link them with a tunnel running under the Baltic sea.

The Fehmarnbelt Fixed Link will be the longest undersea road and rail tunnel in the world: 18 km in length, constructed by immersing 79 prefabricated sections into a trench dug into the seabed up to 40 meters deep.

Each section is 217 meters long, 42 meters wide, and weighs as much as 13 cruise ships. The structure will house two railway tracks and four highway lanes, along with service tunnels and cutting-edge safety systems.

Work began in 2020 and is progressing rapidly toward its planned opening in 2029.

Both the Brenner Tunnel and the Fehmarnbelt are not just feats of engineering but strategic infrastructures that will change the map of European transport.

Thanks to the Brenner Base Tunnel (BBT), rail travel time between Fortezza and Innsbruck will be halved from two hours to about 50 minutes, eliminating the Alpine gradients that force freight trains to make frequent stops and slowdowns. It’s estimated that the Brenner Tunnel will shift a significant portion of freight traffic from road to high-speed rail, reducing the noise and air pollution levels that afflict the Isarco Valley and Austrian Tyrol.

Equally revolutionary will be the Fehmarnbelt Fixed Link. Currently, the ferry crossing takes 45 minutes, in addition to waiting and boarding times. With the tunnel, the journey will take 7 minutes by train and 10 minutes by car, making it possible to travel from Copenhagen to Hamburg in two and a half hours instead of the current five. According to Femern A/S, the Danish company managing the project, the new high-speed connection will generate economic benefits of around €3 billion for the Danish economy and at least double that when considering the entire Baltic region.

The Brenner Base Tunnel looks south, integrating Italy’s high-speed rail network with the German railway axis. The objective? To connect Naples and Rome to Munich with a link that’s competitive even with air travel.

The Fehmarnbelt Fixed Link looks north, linking Scandinavia to Central Europe via a new trade route that facilitates interchange between Baltic ports and continental markets.
Two complementary visions that converge in the European TEN-T strategy and bolster the Green Deal: by 2050, at least 50% of freight transport will need to move to rail or navigable waterways.

The Brenner Base Tunnel and the Fehmarnbelt Fixed Link aren’t just tunnels; they’re political, economic, and cultural projects. They shorten geographical distances, but also the distances between citizens, regions, and opportunities.

As Robert Schuman, one of the founding fathers of the EU, recalled in 1950: «Europe will not be made all at once, or according to a single plan: it will be built through concrete achievements which first create a de facto solidarity».