Portuguese 
English 
Spanish 
4 min of reading 
0 comments 
It is 64 kilometers of tunnel drilled up to 1,720 meters below the peak of the Alps — the Brenner Base Tunnel will become the largest continuous underground railway passage in the world, connecting Austria and Italy beneath one of the highest mountain ranges in Europe
Between Innsbruck, Austria, and Fortezza, Italy, there is one of the oldest and busiest mountain passes in Europe: the Brenner Pass.
For centuries, trucks and trains have ascended and descended the mountain via winding roads and steep tracks.
Now, a team of engineers is drilling through the mountain from the inside.
-
Norway is drilling 27 kilometers of rock 392 meters below the bottom of a fjord to build the world’s largest and deepest underwater road tunnel — when completed, a 21-hour journey will be reduced to 10.
-
After 14 years of construction and a diplomatic crisis that nearly led to a military confrontation over control of the Nile, Ethiopia inaugurated the largest hydroelectric power plant in Africa — the dam is 170 meters high, holds 74 billion cubic meters of water, and generates 5,150 megawatts.
-
Finland inaugurates a gigantic 1.2 km bridge over the sea, where cars are prohibited, featuring a 135-meter pylon and a structure designed to withstand ice, saltwater, and weather for up to 200 years.
-
The new terminal at New York’s JFK Airport, the size of the Empire State Building lying down, cost $9.5 billion, has 13,000 solar panels on the roof, and will open its doors in 2026 in time to host the World Cup.
The Brenner Base Tunnel will be 55 kilometers long — or 64 kilometers if including the Innsbruck detour — making it the largest continuous railway tunnel in the world.
According to BBT SE, the company responsible for the project, the excavation has already removed 21 million cubic meters of rock from the mountain.
In September 2025, the exploratory tunnel completed the first cross-border breakthrough, connecting Italy and Austria 1,400 meters below the Brenner Pass.
The impressive numbers: 1,720 meters of rock overhead
The tunnel reaches up to 1,720 meters below the surface at its deepest section.
There are two parallel tubes, each with a diameter of 8.1 meters, separated by 40 to 70 meters.
Cross passages connect the two tubes every 333 meters for emergency and ventilation purposes.
In the center, a third exploratory tunnel — 12 meters below the main ones — serves for drainage, maintenance, and emergencies.
The gradient is only 0.4% to 0.7%, allowing for an almost flat and straight route beneath the mountain.
This means that trains do not need to climb the mountain — they pass underneath it as if it did not exist.
From 80 minutes to 25: the journey that will change
Today, the train journey between Innsbruck and Fortezza takes 80 minutes for passengers.
With the tunnel, it will drop to 25 minutes.
For freight trains, the current time of 105 minutes will fall to 35.
Passenger trains will be able to reach 250 km/h inside the tunnel.
Freight trains, 160 km/h.
The route will be 20 kilometers shorter than the current one.
It’s as if the mountain were simply removed from the way.
A construction that started in 1999 and is still not finished
The preparations began in 1999.
The exploratory section started in 2007.
The main tunnels began to be drilled in 2011.
In 2019, two Austrian segments were connected, forming 36 continuous kilometers — 65% of the total.
In May 2025, the TBM (tunneling machine) named “Flavia” completed 14 kilometers on the Italian side.
In September 2025, came the historic milestone: the first cross-border breakthrough, connecting the two countries beneath the Alps.
Full operation is expected after 2026.
Who is building it and how much does it cost
The project is managed by BBT SE (Brennero Basis Tunnel SE), a mixed Austrian-Italian company.
Engineering consortia, such as the one led by the Italian Webuild, operate the TBMs.
The Brenner Base Tunnel is part of the Scandinavian-Mediterranean Corridor of the European Union’s Trans-European Transport Network (TEN-T).
This means that EU funding is involved.
The total cost is estimated to be several billion euros, although the exact updated figure has not been publicly disclosed.
Brenner vs. Gothard vs. Eurotunnel: the race of the giants
The current record holder in length is the Gotthard Base Tunnel in Switzerland, at 57 kilometers.
The Brenner, with 64 km including the Innsbruck detour, will be larger.
The Eurotunnel between England and France is 50 km, but it is underwater — a different engineering feat.
Switzerland inaugurated the Gotthard in 2016 after 17 years of construction. The Brenner is on the same path — longer and deeper.
There is also the project for the Mont d’Ambin Base Tunnel between France and Italy, which may surpass both in the future.
Removing trucks from the Alps: the environmental impact
One of the main goals of the project is to transfer freight transport from roads to rails.
Currently, millions of trucks cross the Brenner Pass every year.
Pollution, noise, and wear on the alpine roads are chronic problems.
With the tunnel, much of this freight will be carried by electric trains within the mountain.
Fewer trucks in the Alps = less emissions, fewer accidents, and less congested roads.
The almost zero gradient of the tunnel also optimizes the energy efficiency of trains — unlike the current steep ascent.
21 million cubic meters of rock: where did it all go?
Drilling 64 km of mountain generates an absurd amount of material.
That’s 21 million cubic meters of rock extracted.
Part of this material has been reused as fill for access lines and as aggregate for the internal lining concrete of the tunnel itself.
The remainder was directed to previously authorized deposit areas.
Approximately 60% of the excavation is in Austrian territory.
What could cause delays
Projects of this magnitude rarely finish on the original schedule.
The Gotthard took 17 years. The Brenner has been under construction for 15 years, and full operation still does not have a set date.
Alpine geology is unpredictable — fault zones, water pressure, and rock temperature vary.
Additionally, there is debate about whether the Brenner will truly be the “longest” when completed, as the Gotthard plans extensions that could change the ranking.
But what has already been built is impressive.
The first cross-border breakthrough of 2025 proved that connecting two countries 1,400 meters beneath a mountain is possible — the rest is a matter of time.
Seja o primeiro a reagir!