Expenditure of at least €300 billion in infrastructure investments will be needed to bring Italy out of the national crises caused by the coronavirus pandemic and its economic consequences was a message delivered by Pietro Salini, Chief Executive of Webuild, on the occasion of a TBM breakthrough and 65% completion of the Terzo Valico highspeed railway project on the Genoa-Milan connection in northern Italy. “I see there is a big political debate over the recovery plan,” said Salini to an audience that included the Italian Infrastructure Minister Enrico Giovannini (connecting remotely), Terzo Valico Commissioner Calogero Mauceri, Chief Executive of Ferrovie dello Stato Gianfranco Battisti, the Governors of Liguria and Piemonte Regions Giovanni Toti and Alberto Cirio and leading infrastructure engineers of Consorzio Collegamenti Integrati Veloci (COCIV) consortium building the 53km highspeed railway, 34km of which is aligned underground.

“Investments in infrastructure over a period of six years of nearly €50 billion is foreseen, which represents about 0.5% of GDP," said Salini. "Before Covid, the country spent about 2% of GDP in infrastructure. So, to revive the economy, we need a big boost and more spending. We are talking about at least €300 billion, which is in line with investments being made by other European countries in infrastructure. I hope to see projects for new infrastructure start soon with a long-term vision for our country. It is the creation of employment that should be at the top of everyone’s minds.”

Salini was speaking on the occasion of the breakthrough of the second TBM working on the Serravalle Tunnel on the Terzo Valico project, currently the largest infrastructure project in Italy. About 6.4km of the 7km long twin tube tunnel was completed by the two TBMs breaking through into sections of drill+blast from the opposite portal. The first TBM completed its 6.4km drive in September 2020 with the second in April 2021 establishing an uninterrupted connection of work sites along a 22km section of the railway on the Piemonte side of the project (Fig 1). The two 10m diameter TBMs on the Serravalle drives faced complex situations with the alignment passing under the historic Genoa-Turin railway and requiring innovative monitoring systems above and below ground.

Planning for the Terzo Valico project began in the early 2000s and after being approved in 2006, a turnkey contract of €4.5 billion was awarded to the COCIV consortium In November 2011. The contract is under supervision by ITALFERR and was scheduled originally for completion in 2021. The project includes two long tunnels, the 27km long Valico Tunnel, which will become the longest rail tunnel in Italy, and the 7km long Serravalle Tunnel. Drill+blast progressed from several adits to excavate the 18km southern section of the Valico Tunnel and four EPBMs from Herrenknecht completed the 9km twin tube Valico Tunnel northern section. The two Serravalle Tunnel EPBMs completed 6.4km of the 7km twin tubes, breaking through into junctions with conventional excavations from the opposite portals.

The new rail connection will reduce travel times between Genoa and Milan and will join the Rhine-Alpine corridor of the Trans-European Transport Network (TEN-T). In his presentation at the breakthrough, CEO Salini said: “The Terzo Valico construction site showcases the excellences as well as the problems of the country. A particular problem is the length of time taken for the approval process for large infrastructure projects. The secret to reviving the sector is to be able to do the projects with simple approval processes in line with European rules, but we need to believe in it and put ourselves, together with the supply chain of thousands of businesses, at the service of the country.” At the World Tunnel Congress in Naples in 2019, Salini gave a keynote presentation in which he also emphasised the need to attract young professionals to the underground engineering industry and addressed the topic of risk aversion and unrealistic competition in the contracting sector, saying that the continuing attempts by owners to shift risk onto contractors bidding with ever decreasing margins will lead to extinction of contractors.

Webuild emerged in 2020 from the construction company Salini Impregilo and take over of several other Itallian contractors. As a signatory of the United Nations Global Compact initiative, Webuild is engaged on major national and international projects including, the Grand Paris Express in France, the Snowy 2.0 hydro project in Australia, and the Anacostia and Northeast Boundary CSO projects in Washington DC, USA. In 2020, the order book of the group totalled €41.7 billion with 89% of the work load involving projects that support the Sustainable Development Goals adopted by all United Nations Member States in 2015.

The Terzo Valico high speed rail project in Italy is at the south end of a EU priority transport upgrade of the Rhine-Alpine rail corridor that extends between Genoa and Rotterdam via Switzerland and Germany (Fig 1). The project is being developed by Italian rail network company RFI SpA as a mostly underground alignment of twin tube tunnels at about 35m apart and linked with cross passages at 500m intervals.

Planning for the project began about 12 years ago, and in 2006 the design concept was approved. In November 2011, the all-Italian Consorzio Collegamenti Integrati Veloci (COCIV) led by Salini Impregilo and including Condotte and Civ was awarded the turnkey contract to fully deliver maximum design rail speed of 250km/hr Terzo Valico, including all civil and M&E works and detailed engineering. With a total value of approximately €4.5 billion, the contract is under supervision by ITALFERR and is scheduled for completion in 2021.

Construction is arranged in six packages with excavation of two long tunnels taking more than 34km of the total 54km long connection through TBM and conventional open-face tunnels to maintain high speed rail services.

To the south the link, the Valico Tunnel, at 27.1km long, takes the rail line almost as far south as Genoa, linking into the southern rail network via the conventional open faced Campasso Tunnel completed by COCIV in July 2015 and new interconnection tunnels of about 2km each to Voltri (Fig 1b).

To the north and separated by a short surface section between portals is the shorter 7.1km long Serravalle twin tube tunnel.

The strategy of the main contractor is to subcontract execution of the main line TBM excavations and is completing the open-face conventional headings itself. Seli Overseas is signed as TBM subcontractor on the Serravalle Lot, and it is on this section where the first of four TBMs procured for the project will launch in the coming weeks.

TunnelTalk met COCIV General Manager Ettore Pagani at the 2016 Swiss Tunnel Congress who explained that procurement plans are in preparation for a second TBM excavation subcontract for the 9km long northern portion of the long Valico Tunnel where the second pair of TBMs will be launched in 2017. For the 18km southern section of the Valico Tunnel, the contractor is using conventional open-face tunnelling methods on several headings opened up from a number of intermediate adits.

Addressing the recent Swiss Tunnel Congress, Pagani reported that at the end of May, the project had completed a total of about 7.5km of tunnel excavation including starter tunnels at the portals, completion of the Campasso Tunnel, and excavation of two of the Valico tunnel adits at Vallemme and Polcevera.

By 2017, with conventional open face tunnelling under way on the main tunnel headings in the south, and all four TBMs in operation in the north, a total of 10 headings will be under excavation, said Pagani. These operations will be supported by seven base camps and 17 construction sites along the whole length of the project.

The four TBMs for the main tunnel bores were ordered from Herrenknecht AG following earlier use by COCIV of a Herrenknecht machine to bore the 1,958m long intermediate adit at Polcevera for the long Valico Tunnel. All are EPBMs and the first two of the four will launch before the end of 2016 by Seli Overseas to complete the 6.3km drives for the 7.1km long Serravalle Tunnel.

The first of the two 9.73m diameter EPBMs for the Serravalle Tunnel is under assembly ahead of a launch in September/October (2016).

Geology along the twin tunnel alignment comprises mostly clays, sandstones, marls and conglomerate. The EPBMs will be launched under a low overburden from the north portal and will install a 400mm thick precast concrete segmental lining 1.8m wide rings of six segments and a key as they progress.

Excavation of the Valico Tunnel involves tunnelling through more complex geology. “The tunnel is only half as long as the Gotthard high speed rail base tunnel but it will be challenging to build,” explained Pagani. “Almost a third of the alignment traverses the Sestril Voltaggio Zone under an overburden of up to 600m and through a long fault zone.

When speaking to TunnelTalk, Pagani said that the geology of the northern and southern sections of the long Valico Tunnel are distinctly different. “Rock towards the north is similar to conditions on the Serravalle alignment,” he said “comprising sandstones and marls but with an expectation of medium to high fracturing. Most of the rest of the tunnel to the south, conditions consist of schists, hydrogeological features, occasional limestones with notable fracturing and the anticipation of high deformations.”

The southern portion also features the geological complication of localised deposits of asbestos in the face of one of the adits.

For the 9km long northern portion of the Valico Tunnel, COCIV has selected a pair of 9.77m diameter Herrenknecht EPBMs machines that are to launch in 2017.

Ahead of that COCIV is performing a total 6km of adit construction and advancing the 18,000m southern section of conventional open-faced mined tunnels for the Valico Tunnel.

Initial works have focused on excavation of the four adits in preparation for opening up the main tunnels. These are located, from the north, Vallemme (962m), Castagnola (1,782m), Cravasco (1,260m), and at Polcevera (1,958m long).

In July 2015 the JV completed the first, relatively short, section of main tunnel – the Campasso Tunnel at the southern end of the Valico Tunnel. This alignment takes the main running tunnels off and into a single tube, twin track tunnel for linking with local rail networks.

Excavation of the 1,260m-long Cravasco adit has been unexpectedly challenging due to particular difficulties in dealing with naturally occurring asbestos. The asbestos zone was encountered earlier this year (2016) along a stretch of approximately 100m starting at about 700m into the heading. The contractor is operating a three-zone (A-C) isolation and handling system to deal with the excavated asbestos, starting with sliding doors and waterproofing material, to prevent contamination as the fibres are removed for processing. The asbestos is handled as hazardous waste and is being stored as such until final disposal, explained Pagani.

With work well underway excavation of the main tunnels from the total of 10 headings will progress towards TBM and open-face breakthroughs and towards an opening of the new line in 2021.