Largest-ever Euro TBM completes drive

21 July 2020

TBM-maker Herrenknecht announced on July 17 that one of its TBMs – hailed as the largest ever built in Europe – had holed through in Italy in June. The 15.87m-diameter machine started tunnelling through the Apennine Mountains in June 2017 and has excavated 7.5km, with advance rates of up to 122m/week.

Tunnellers encountered a complex geology comprising limestone, marl, siltstone, shale and sandstone. Furthermore, Herrenknecht said it worked closely with local contractor Pavimental to devise a system that protected site crews from the anticipated dangers of methane gas.

The newly-excavated, three-lane Santa Lucia tunnel will form a key section of the A1 highway expansion between Bologna and Florence. Due to the previously winding nature of the road, the tunnel is expected to reduce travel times and the likelihood of accidents, as well as lower overall vehicle emissions in the vicinity.

The project is also notable for breaking the previous TBM-diameter record held since 2010 by a 15.55m Herrenknecht EPB shield that had excavated the Sparvo tunnel – also part of the A1 motorway project.