The excavation of the last 1,331-meter tunnel ‘A’ of the M6 motorway between souhern Hungary's Szekszárd and Bóly is finished, the principal contractor of the implementing MAK Zrt consortium, Strabag said in a press release.
With this Strabag AG completed the excavation of the tunnels within one and a half year period. Tunnel ‘A’ is the longest of the four M6 tunnels.
Tunneling was performed by using a special Austrian closed technology, called NATM. The essence of this method is that the top-heading, bench and invert are excavated separately with a shotcrete temporary support. With this method the 46-meter cover above tunnel ‘A’ consolidated quickly. The latest was the last of the four.
Including the precut section of the tunnels altogether 600,000 cubic meters (cbm) of soil was excavated and 150,000 cbm shotcrete was used. The construction was continuous, 24 hours a day, and there were times when 120 miners worked at the same time, the statement reads. (press release)