It will be a core element of the trans-European corridor between Scandinavia and the Mediterranean and set a new standard for crossing the Alps while also earning the title of longest underground railway connection in the world. Without a doubt, the Brenner Base Tunnel will be a central artery for rail transport in Europe – and the recent main-tunnel breakthrough between Italy and Austria marks a historic step forward. However, it will still be some time before the tunnel is fully operational.

“Ah, yes, the Brenner,” is just the sort of resigned expression you can expect from a vacationer who has experienced the pass’s infamous traffic jams or even from a logistics specialist who is dreaming of a fast connection between northern and southern Europe. The Brenner Pass at the border between Austria and Italy is the most heavily traveled alpine crossing for both road and rail traffic. Over 30% of all goods traffic crossing the Alps runs over the Brenner, with about 70% traveling by road and 30% over the existing railway line. Trucks alone account for 2.5 million vehicles crossing the Brenner each year. Which naturally means: traffic jams, noise, annoyed residents and high environmental impact.

It’s no wonder that the Brenner is so popular, though. At 1,370 meters, it is the lowest pass in the Alps, making it an ideal north-south transit route within the EU. The Brenner Base Tunnel is being built as an alternative to the highway and the existing railway route and should improve the environmental situation here as well. The dedicated railway tunnel is intended primarily to promote a shift of heavy traffic from the road to the rails. In addition, the new route will slash passenger travel times from 80 minutes down to just 25.

Centerpiece between Helsinki and Malta

The Brenner Base Tunnel is an important piece of the Trans-European Transport Network (TEN). It will form a central link in the Scandinavian-Mediterranean TEN corridor (SCAN-MED), which runs from Helsinki (Finland) to Valletta (Malta) and connects the urban centers in Germany and Italy with the ports in Scandinavia and the Mediterranean. The entire railway route amounts to 9,400 km. The Brenner Base Tunnel is a central element in this corridor for crossing the Alps. As part of the new Brenner line between Munich and Verona (425 km long), it will bring about a pronounced improvement in travel and transport options in the heart of Europe.

The EU rates the tunnel as a priority infrastructure project and is subsidizing the construction costs at up to 50%. The other half of the cross-border project is being financed jointly by Austria and Italy. The infrastructure project therefore also serves indirectly as a symbol of unity in the heart of Europe.

Explosive drilling and an underground border crossing

The logistical significance of this new high-capacity connection from Innsbruck (Austria) to Franzensfeste (Italy) cannot be overstated. The tunnel runs not only under the Alps, but directly beneath the Italian-Austrian border as well. Excavation teams already crossed this subterranean border in November 2021 – 1,450 meters below the surface, yet still at an altitude of approximately 794 meters. The connection of the two main tunnel tubes in late July 2026 marked a technical milestone, as the breakthrough meant that all 230 kilometers of the Brenner Base Tunnel had been successfully excavated.

Incidentally, on the Austrian side, the tunnel was constructed using drill and blast methods, while on the Italian side, tunnel boring machines were used.

Breakthrough achieved – completion to follow

After its completion, which is currently expected in 2032, it will be the longest underground railway connection in the world. The tunnel section from Innsbruck to Franzensfeste runs a total of 55 km. Including the existing bypass around Innsbruck, the length will be 64 km. This is enough to surpass the current record holder, the 57.1 km long Gotthard Base Tunnel in Switzerland.

Taken together, the two main single-track tunnel tubes of the Brenner Base Tunnel add up to 120 km. Including the exploration tunnel, which runs 12 m below the middle of the main tunnel tubes and will provide drainage when the tunnel is complete, the total is 181 km. Adding in cross passages, rescue tunnels and the four entry tunnels yields a grand total of 230 km. That corresponds roughly to the distance from Innsbruck to Venice as the crow flies. It may not run under a large body of water like the Channel Tunnel, but it is no less spectacular and definitely a feat of engineering.

The “flying junction” of the tunnel tubes near Innsbruck is also quite impressive. Since the trains coming from Italy travel on the left, while the Austrian trains travel on the right, this measure eliminates a crossing of the tracks.

Previous route a bit too steep

The need for the Brenner Base Tunnel is somewhat connected to the existing railway route, which was opened in 1867. This line section has an incline of up to 26‰ and crosses the Brenner Pass at an elevation of 1,371 m. Both the incline and the capacity limits pose problems, especially for goods traffic. This makes the Base Tunnel an attractive proposition since it is being run as a flat tunnel right underneath the pass. It only has an incline of max. 7‰, which requires much less energy from the trains and significantly reduces the travel time – from the current 80 minutes to just 25. The speed for passenger traffic will be up to 250 km/h and for goods traffic up to 160 km/h. In addition to the shorter travel time, it will also be easier to time the train traffic. The overall goal is to shift traffic from the road to the rails, lowering the impact on people and nature while also providing greater safety from natural hazards – in other words mudflows, avalanches and even earthquakes.

Pyramids in the Alps?

As with all major tunnel projects, the boring process produces spoils – and in this case a massive amount: 21.5 million m³. Try to imagine: that would be enough to build about eight copies of the Great Pyramid of Giza. Right there in the Alps…
The plan is for one third of the material to be processed and reused, while two thirds will be deposited near the tunnel and then fully renatured. Protection of the environment has of course not been neglected: measures include cleaning the construction site water before releasing it into rivers, monitoring the air quality in the area and setting up nesting and feeding sites for the animals in the vicinity of the construction sites.

The Brenner Base Tunnel meets the highest safety standards. The two 8.1 m wide tunnel tubes each feature a single railway track. A cross passage connects the tubes every 333 m. These passages would serve as escape routes in an emergency. Three underground emergency stations are spaced at 20 km intervals for pulling over if unforeseen events occur. These are about 500 meters long and are connected to the middle tunnel every 90 meters. Ventilation cross passages are offset from these every 45 meters, making them spaced at 90 meters. The middle tunnel contains a false ceiling. Above this, any smoke from a fire will be extracted; below, fresh air is blown into the safe areas. The emergency stations are connected to the access tunnels and the outside area, which allows positive fresh air pressure to be built up in the middle tunnel to keep the escape routes free of smoke. In an emergency, passengers can be evacuated through the safe middle tunnel and rescued either directly via an access tunnel or with a rescue train.

Historic trade route and “freight explosion”

The importance of the Brenner as a trade route can be seen in its long history. Its relatively low elevation alone made it one of the most important north-south connections in Europe even in the earliest times. In the early Bronze Age, about 1,700 BC, it was already a valuable trade connection between the North Sea and the Mediterranean region. The Romans then built a paved road (primarily for military reasons). In the Middle Ages, the Brenner Road became part of the famed “Strada d’Alemagna,” which ran from Venice to Augsburg and served as one of the most important trade routes in the European region. The significance for goods traffic developed in the late Middle Ages, in the 14th century, when 3,000 tons of goods (spices, wine, sugar, oil and cotton) were transported over the Brenner in carts every year. A regular postal connection through the pass followed in 1522.

At the start of the 19th century, horse-drawn carriages were bringing 15,000 t of goods over the Brenner each year, while 50 years later, this had grown to 60,000 t. The rapidly increasing demand then led to the creation of the Brenner railway, which was considered a technical wonder at its opening in 1867.

When the “Brenner Autobahn” was completed at the start of the 1970s, the volume of goods moving through the pass each year only expanded further, most recently reaching 50 million tons per year (about 70% by road and 30% by rail). Of the last 11.5 million trucks to cross the Alps, 2.5 million took the Brenner. In other words, it is high time to move this goods traffic from the road to the rails!

We are eagerly awaiting the planned completion in 2032 and congratulate the project partners and construction teams on the successful connection of the two main tubes.