Mules, Italy - The TBM Serena has started excavating in the Brenner Base Tunnel construction site in Mules. Serena will bore an investigation tunnel to analyse the soil conditions, helping to reduce construction costs and times. The tunnel will be 14km long. More than 10 meters above this investigation tunnel, TBMs Virginia and Flavia will follow, excavating the railway mainlines, consisting of two parallel tubes. The Brenner Base Tunnel Lot "Mules 2 -3" is the last stretch on italian grounds, extending up to the austrian border.