2. Method of construction and excavation

The proposed layout of the tunnel and shafts takes the following factors into account:

• geological checks and soil homogeneity ;

• the type of terrain encountered, which defines the type of machine to be used;

• the type of material to be used for the work;

• determining the pickling system;

• types of injections to be performed ;

• possible distances between wells ;

• checking high and low water levels;

• environmental constraints, which are :

  • utility and concession works already located underground,

  • surface traffic (pedestrians and vehicles),

  ...