May 27th saw the handover ceremony of the Herrenknecht Variable Density TBM – attended by representatives from Herrenknecht, contractor SIS JV (Finninc and Sacyr), and FCE (Ferrovia Circumetnea) – that will be used to bore sections of the 8.5km long tunnelled alignment of the 14km long, €800M Metropolitana di Catania expansion in Sicily.
The Italian Ministry of Infrastructure and Transport awarded SIS the metro section between the towns of Misterbianco and Paternò in September 2023, as well as an additional section between Monte Po and Misterbianco in December 2024, which connects to the currently operating line in Catania (Sicily).
The terrain that characterizes the surroundings of the Sicilian city of Catania is unique due to the presence of Mount Etna. The eruptions over time have shaped a highly variable subsoil.
The VD-TBM stands out for its adaptability to the area’s changing geological conditions. Additionally, due to the frequent seismic activity generated by the volcano, it is necessary to comply with strict seismic standards for both permanent and temporary works.
“A few years ago, the city already undertook a metro project using a conventional TBM, and it ran into significant difficulties due to the unfavorable geological conditions”, explains Miguel Ángel Montón, tunnel manager for this project.
“The ground is extremely complex due to its heterogeneity; there are fissures, cavities, and frequent alternations between basaltic rock—lava—and softer soils. Our TBM is highly adaptable to current conditions; its operating mode can be changed on the fly using four different excavation modes, allowing us to respond in real time to the terrain. It is more complex to operate, but offers that flexibility”, Montón adds.
The manufacture of the TBM began in August 2024 and operational testing started in May this year. Disassembly and transport to the construction site are scheduled to begin in June, with arrival expected in July.
The heaviest components will be transported across the Alps using special convoys to the port of Ravenna (Italy), from where they will be shipped to Catania. The smaller components will be transported by truck to across the Strait of Messina to reach Sicily.
On-site assembly of the machine will take around three months, followed by approximately two weeks of commissioning and testing. Excavation is expected to begin by the end of December or early 2026.
“We will excavate around 5km of tunnel with this TBM. The initial contract was for 3,200m, and with the most recent award, an additional 2km were added,” Montón explains
Herrenknecht
Pioneering Underground Technologies - Herrenknecht AG is the technology and market leader in mechanized tunnelling. As the only company worldwide, Herrenknecht delivers cutting-edge tunnel boring machines for all ground conditions and in all diameters - ranging from 0.10 to 19 meters.
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