A historic handshake in the heart of a mountain – the world’s largest railway tunnel system is being built in the Alps

A memorable moment during the construction of the Sopron tunnel on the M85 was when the tunnelling machines first met in the southern, and then in the northern tunnel. The atmosphere experienced there was felt even more intensely in the tunnel being built beneath the Brenner Pass: on 28 July, contractors from the two countries met at the Italian-Austrian border as part of one of Europe’s most significant railway development projects.

According to the railway.pro report (in its own right) states that the project teams working on the Brenner Base Tunnel – set to become the world’s second-longest tunnel – have met some 1,400 metres beneath the Brenner Pass, which forms the border between the two countries – almost simultaneously in both tunnel tubes.

This breakthrough also marks the convergence of two construction projects that have been progressing independently of one another for several years. On the Italian side, the tunnels were excavated using the Virginia and Flavia tunnel-boring machines, whilst the Austrian section was excavated using conventional drill-and-blast methods.

A key objective is to reduce the heavy lorry traffic

The Brenner Base Tunnel (BBT) is one of the most ambitious projects in European transport infrastructure, which will link Innsbruck in Austria and Fortezza in Italy beneath the Alps.

The Brenner Pass is the bottleneck of the busiest land freight corridor between Northern and Southern Europe. One of the main aims of the project is to shift a significant proportion of the heavy lorry traffic from road to rail.

At present, trains use the Brenner railway line, which runs over the Brenner Pass and is extremely steep, often hauled by two electric locomotives; their speed barely exceeds 70 km/h. As a result of the project, journey times for passenger trains between Innsbruck and Bolzano will be reduced from around 2 hours to just under 50 minutes, whilst drastically reducing noise and air pollution in the Alpine valleys. Once the line opens, the planned service will consist of 80 passenger trains and 320 freight trains per day.

The leading players in the international tunnel-building industry are in attendance

Although the base tunnel is 55 km long, it will form a continuous 64-km underground section when connected to the existing Innsbruck tunnel – making it the world’s longest continuous underground rail link.

However, the tunnel system does not consist solely of two one-way tubes: together with the main tunnels, the connecting tunnels between them, the exploratory and research tunnels, and the emergency exits, the total length of the system exceeds 230 kilometres. It is no wonder that the project involves the leading players in the international tunnel-building industry:

• Webuild: It is by far the largest Italian participant in the project, acting as lead partner or a partner in several Austrian and Italian sections.
• PORR & STRABAG: Two giants of the Austrian construction industry, responsible for drilling the tunnel systems on the Austrian side, which stretch for tens of kilometres.
• Ghella: An Italian giant specialising in civil engineering and tunnel boring, with expertise in drilling in Alpine rock formations.
• Implenia & Marti: Switzerland’s leading tunnel-building companies, which, following the Gotthard Base Tunnel, were also given a key role in the application of specialised technologies at the Brenner.

The Brenner Base Tunnel is expected to become operational in 2032; according to the latest report by the European Court of Auditors (ECA), its total cost is €8.37 billion.