ABSTRACT
Line C is the third line of Rome underground system. Two TBMs are being used to excavate the tunnels at a depth ranging from 30 to 60 m below ground level. The job sites are located in the centre of Rome, in an area characterized by several historical buildings: as a consequence, technical and operative choices have been imposed, to minimize the job sites dimension. This approach required Metro C to use unconventional methods to start the TBM excavation from shaft 3.3, located in the “Via Sannio gardens” very close to the Aurelian Walls at Porta Asinaria. The two TBMs were lowered into this shaft to build the two tunnels which will run as far as Amba Aradam station, over a length of about 400 m each. In order to complete the shaft itself and the tunnels to San Giovanni station, as soon as the TBMs arrive at Amba Aradam station, the TBM site equipment will be moved into this station area to complete the excavation planned for the remaining stretch. Tunneling started last March and an accurate structural and geotechnical monitoring system was installed in the soil and on the existing buildings adjacent to the line, in order to check in real time the level of interaction with the excavations.
