§ Construction of reinforced concrete shafts.
§ Sinking shafts as caissons under free and compressed air pressure.
§ Diversion of public utilities (Electricity, Gas, Water, Telephone, Sewage...).
§ Driving tunnel (2.87 m - 2.20 m I.D.) with Earth Balance Machines (Tunnel Boring Machines).
§ Erection of the primary tunnel lining (Reinforced concrete segments).