PORR CEO Karl-Heinz Strauss pays tribute to the exceptional performance of the teams: “A milestone moment like this is the result of dedication, professional expertise and team spirit. Our employees have managed something extraordinary under challenging conditions. Together with all project stakeholders, we’ve already achieved an enormous amount, even if important tasks still lie ahead of us. Today we’re celebrating this success and looking back with pride on our own achievement”.

The breakthrough took place around 1,408 m beneath the Geigenspitze at an elevation of approximately 794 m above sea level. At the breakthrough site, the tunnelling crews worked their way through central gneiss – a particularly hard rock from the innermost and deepest geological unit of the Tauern Window. Conditions underground were demanding: Rock temperatures of around 30°C, long transport routes and the geological requirements posed difficulties for people and machinery alike.

With the successful breakthrough, Austria and Italy are now permanently connected via the two main tunnel tubes. This is a special moment for the teams involved: After years of intensive work, the Austrian tunnelling crews are meeting their Italian colleagues underground for the first time. The joy and relief at what has been achieved are correspondingly immense.

Utmost precision as a prerequisite for success

Blasting excavation in Lot H53 began in March 2024. Between two and five metres of tunnel was excavated per blasting cycle, depending on the rock conditions. By the time the breakthrough was achieved, around 5.0 km of the eastern tunnel and around 5.1 km of the western tunnel had been driven by drill-and-blast in the H53 Pfons–Brenner construction lot.

The two main tunnel tubes were constructed simultaneously. Six to eight employees worked around the clock on each advance in a four-shift operation. Precise coordination of all works was required in order for both tubes to reach the national border almost simultaneously. This included the exact surveying of the tunnel axes, constantly adjusting the advance rate to the geological conditions, and coordinated planning of personnel, machinery and materials.

Over the entire advance length of more than 5 km, the deviation from the planned tunnel axis was permitted to be no more than a few centimetres. Only thanks to this high level of precision was it possible to successfully join together the tunnel sections driven from Austria and Italy.

The next step on the road to completion

The successful border breakthrough once again underlines the capabilities of the teams involved in the Brenner Base Tunnel. With each further step in construction progress, the completion of one of Europe’s most important infrastructure projects draws nearer, and with it a decisive contribution to sustainable European freight and passenger transport by rail.

With a total length of 64 km, the Brenner Base Tunnel will in future form the most important north-south rail link through the Alps and make a significant contribution to shifting transport from road to rail.

Following today’s milestone, attention is already turning to the next stages of construction. In the coming months, the two tunnel boring machines Olga and Wilma will continue driving the main tunnel tubes towards Innsbruck. This brings this key European project another step closer to completion.