The choice of tunnel boring machine is specifically based on the conditions of the rock in place. An exhaustive geotechnical campaign was conducted for this project. The following field and laboratory tests were performed:

• Measurement of groundwater level;
• Geocamera survey;
• A structural description of the rock and geomechanical classification with data interpretation;
• Uniaxial compression and tensile strength tests;
• Cherchar abrasivity test;
• Determination of bulk density;
• Lugeon pressure water test.

Following the analysis of the geotechnical data, several tunnel boring techniques were considered, and the microtunneling technique proved to be optimal. 

Design calculations were specifically executed for the microtunneling technique according to industry standards.

• Constraints induced on the face of the microtunneler;
• Friction on the pipe;
• Thrust forces;
• Thickness and strength of the pipe;
• Annular pressure;
• Rheological characterization of the drilling fluids.