Valico Bypass – Lots 6-7

Lots 6 and 7 – Works to upgrade La Quercia-badia Nuova section, between Sasso Marconi and Barberino del Mugello

  • Location: Italy – Emilia Romagna
  • Client: Autostrade per l’Italia S.p.A
  • Project value: € 701.139.576

Works on Lots 6 – 7 involved the construction of a new motorway section (approx. 7.5 km) following the construction of four tunnels with a total length of approx. 9,300 m and two viaducts with a total length of 2,000 m,The composite steel -concrete deck is constrained with anti-seismic devices. The works also comprise 1,200 m of embankment section and minor works such as underpasses, manholes, reinforced earth walls, reinforced concrete walls as well as service road works.

The main structure of lots 6 and 7 is the Sparvo twin tube tunnel having each a length of two km and the Val di Sambro tunnel (excavated with traditional boring method). The northbound tube is 2,564 m long and the southbound one is 2,600 m long. The carriageways of both structures accomodate three lanes and are connected with vehicle and pedestrian bypasses for emergency evacuation purpose.

The Sparvo tunnel excavation was initially based on the traditional sequential excavation method with a series of typical sections, depending on the different geo mechanical parameters along the vertical alignment; However, the difficult geo-mechanical conditions, the uncertainties in the advancement rate, the risk of instability of the tunnel front face and the desire to improve the safety conditions of workers, have led the engineers to propose an alternative excavation method. Thus was born “Martina”, an EPB Type TBM with a spectacular 15.62 m outer diameter and equipped with explosion-proof technology, expressly designed and built for this project. The work is complemented by the Molino di Setta viaduct, having a 530 m long steel-concrete mixed deck, with a maximum central span of 100 m as well as the Sparvo viaduct, having a 500 m long deck in mixed steel-concrete, with a central span of 120 m. Both structures are equipped with anti-seismic devices.

Martina, as high as a 5-floor building, was the largest tunnel boring machine in the world, it was acquired by TOTO S.p.A. Costruzioni Generali in 2010 from Herrenknecht AG for a total investment of € 53 million. Martina advancement rate is more than 12 metres per day, compared to 15-20 metres per month obtained by adopting the traditional SEM technique.Therefore, eliminating the long time cycle requested for consolidation, excavation and matrial dumping , as well as losses associated with possible colloapes of the excvation front face. The mechanized excavation method also drastically reduces risks on the safety of workers hence could operate in a protected environment.

Martina TBM data sheet

  • Excavation diameter: 15.62 m (equivalent to a 5-floor building)
  • Total length: 130 m
  • Cross section area: 192 m2
  • Thrust value: 39,485 t
  • Total weight: 4,500 t
  • Total installed power: 18 MW

The records of TBM “Martina” on the first tube are :

  • Maximum daily output: 11 tunnel rings equivalent to 22 meters of tunnel alignment
  • Maximum weekly output: 61 tunnel rings equivalent to 122 meters of tunnel alignment
  • Maximum monthly output: 203 tunnel rings equivalent to 406 meters of tunnel alignment