“Central Subway”- Metro line 2 in San Francisco

The project involved the underground extension of the current surface metro line which passes through the centre of San Francisco. The plan for this part of the project was to drill two parallel 2.6-kilometre tunnels for the passage of subway trains, as well as four stations. Exacvation was completed by '2 EPB Robbins with 6.4m diameter; The Italian group Salini Impregilo, its U.S. unit S.A. Healy and partner Barnard C.C.I. Salini Impregilo did the two tunnels, the preliminary work for the future stations, the entry ramp and the extraction well for the tunnel-boring machine (TBM). A biodegradable EP grease was specifically requested in the project specification, therefore the MAPEBLOX EP 2 ECO was chosen to lubricate the TBM main bearing.