The project included planning and accompanying the execution of the tunnelling works, a survey of buildings, preparation of a risk survey of the buildings and infrastructure along the route, the planning of 10 connecting tunnels as well as planning of the mortar works to seal and stabilize the ground and planning of protection works for the buildings.
The TBM EPB method was used for the main tunnels, while the connecting tunnels were constructed using the conventional mining method. The project is characterized by the need to plan and execute the works in a dense urban environment below the groundwater table and in sandy soil, traversing utility infrastructure structures and passing alongside and below buildings that are more than 100 years old.