The works on Tunnel T1 are moving forward!
The new advancement method adopted for the northern front of the left tunnel involves carrying out the excavation according to a much closer sequence of excavation of the calotte/lower/invert, which makes it possible to eliminate very time-consuming intermediate work, such as the calotte invert arch and the micro piles at the foot of the calotte ribs.
The steel invert arch has also been introduced in the first phase lining, to close the lining ring and allow an immediate greater rigidity of the same. The advancement scheme is in fact very close to that of the full section for the short time in which the operations are carried out.
The convergences recorded with this new method have been reduced to a few centimetres, compared to what was recorded in the previous beams, which had given total convergences of up to 30 cm.