With tunnelling well underway in the Austrian-Italian Alps, the Brenner Base Tunnel developer, BBT-SE, is preparing its procurement plans for the final, and largest, tunnel contract packages.

BBT-SE has signalled that a call for bids is planned before the year’s end for the Pfons-Brenner and early in 2017 for the Sillschlucht-Pfons, although it was confirmed to TunnelTalk that a conclusion remains to be reached over the provisional award of the Mules 2-3 Lot of earlier this year.

The Mules 2-3 package is located at the southern Italian section of the project, extending north from Fortezza portal to Brenner and includes 14.7km of the exploratory tunnel; a total 40.3km for the main tunnels (20.15km in each tube), and the St Jodok multifunctional emergency station.

The package has an estimated value of €1.4 billion (excluding taxes) and in March 2016, BBT-SE named an Astaldi-Ghella led JV as being provisionally awarded the contract with a contract bid of €993 million (excluding taxes). The tender assessment was weighted on technical solution, time and bid price. BBT-SE told TunnelTalk that the award has yet to be confirmed and that further details were unable to be disclosed.

Astaldi is the lead JV partner with a 42.51% share, Ghella is the second partner with 42.49%, with each of the three other junior partners – comprising Cogeis, Oberosler Cav Pietro and PAC – holding a 5% share each.

In announcing its provisional selection, BBT-SE said the works were expected to take about seven years, although it had noted previously that the section could take about nine years to complete. Astaldi has said both that open face, drill+blast and TBM excavation is planned for the tunnelling works.

While Mules 2-3 remains to be settled, the developer said it would soon launch procurement for the two remaining northern construction packages on the Austrian side.

The Pfons-Brenner Lot has an estimated construction value also of €1.4 billion and calls for 8.8km of exploratory tunnel and 18.6km in each of the main tunnels. The works will access via the Wolf to advance headings in both directions for the main tunnels and by 3.2km north and 5.6k south in the exploratory tunnel. Additional excavation in the exploratory tunnel was completed as part of the separate Wolf II adit package.

The last of the three major main line packages is the section north from Pfons to Sillschlucht in Austria. The package includes excavation of almost 13.8km of the main twin-tube tunnel excavation and has a BBT-SE estimate of approximately €600 million (excluding taxes). Procurement is expected in 2017 for excavation to begin in 2019.

In total, the Brenner Base Tunnel requires about 230km of tunnels to be excavated and from key adits at Ampass, Ahrental, Wolf, Steinbach and Mules. It will run about 55km between the Innsbruck and Fortezza portals. The twin 8.1m i.d. main tunnels will run 70m apart and will be joined by cross passages at 333m intervals. The 5m i.d. service tunnel runs between the main tubes and about 12m lower in alignment. It is being excavated in advance and in phases, and as an exploratory tunnel. The multifunctional emergency stations will provide access to the surface.

The total length of the Alpine rail project is 64km and it will be the world’s longest tunnel when completed in 2026.

Construction on the project began with initial works in 2007. Progress over the last 10 years has been underway from four active sites Tulfes-Pfons; Isarco River Underpass; Wolf; and Periadriatic Line.

Progress of the works by early August at the sites are:

Tulfes-Pfons

• a relatively short section of main tunnels completed;
• the 9.7km long emergency tunnel (70% done), using the Ampass adit;
• 7km of connecting tunnels (30% done);
• the 1.85km long emergency stop (50%); and,
• a 15km stretch of the exploratory tunnel between Pfons to the Ahrental adit (14% done).

Last year, the Salini Impregilo/ Strabag-led JV launched a 7.93m diameter Herrenknecht TBM on the exploratory tunnel on the Tulfes-Pfons Lot. The contract was awarded in 2014 and requires 38km of tunnelling, including drill+blast work. Tunnelling on the lot is due finishby mid-2019. It is one of two contracts the JV has on Brenner, the other being the Isarco River Underpass at the southern end in Italy near the Fortezza station.

Isarco River Underpass

The JV began construction on the underpass in 2014 and is scheduled to complete the works by late 2022. Ground freezing will take the tunnel under the river and other soft ground works require soil strengthening by jet grouting.

Wolf

Much of the work in the Wolf package has been completed. The 3.2km long access tunnel was completed at the end of 2015 after two years of excavation, and a 1.2km long stretch of exploratory tunnel is almost finished. The contractor is the Swietelsky/ Swietelsky Tunnelbau JV, which was awarded the lot in late 3013 and is due to finish in late 2017.

Periadriatic Line

Finishing works have been underway in the Periadriatic Line from the Mules (Mauls) Adit following excavation between late 2011 and early 2015 through a zone of complex geology on a tectonic plate boundary. The works by the PAC, Cogeis, Oberosler Cav Pietro and Implenia JV excavated 3.7km of the main tunnels and 1.5km of the exploratory tunnel through the fault zone.

Earlier works on the Brenner project included a TBM drive by Seli to advance the exploratory tunnel from the southern end in Italy.