First TBM holes through on Milan M4 central section

11 September 2020

Webuild Group has announced that on 9 September the first of two TBMs boring the central section of Milan’s M4 metro line broke through at the future Solari underground station. The second TBM is expected to hole through in a few days’ time.

In excavating the 9.2km-long, 8.15m ID parallel tunnels, the two TBMs have so far removed 620,000m3 of spoil. Working in complex geological and geo-technical conditions, the excavation reached a monthly production high of 540m.

The line will be 15km long with 21 stations. Taking just 30 minutes to cross the city’s historic centre, the line will link the eastern part of the city where the Linate city airport is located with the San Cristoforo FS station to the southwest. Intermodal connections with other lines will expand the city’s network of public transport to improve the environment, taking some 16 million vehicles off the streets every year and reducing CO2 emissions by 30,000 tonnes/year. The first section of the line between Linate city airport and Forlanini FS station is expected to open in spring 2021.

Commissioned by the City of Milan, the line is being built by mixed concession operator M4, which will also manage the line in which the city and a group of private partners led by Webuild Group are investors. Webuild Group was formed by the merger between Salini Impregilo and Astaldi.