The project, located in the Maia district, consists of building a new gallery, 367 m long, to the north of the existing two, running downward (Ermesinde-Porto), including widening and improvements for 2 x 4 lanes.

The main tasks include:

• Tunnelling (by blasting and mechanical means);
• Provisional shoring of the excavation (concrete launched with metal fibres, Swellex-type bolting, metal crankshafts, sinking minipiles, bolting with fibreglass);
• Waterproofing and drainage (geotextile sheeting and 2 mm PVC membrane);
• Final reinforced lining;
• Electromechanical installations (lighting, ventilation, fire-fighting system, CCTV).

The aim of the project is to achieve a significant improvement in the traffic locally and entering and leaving the city of Porto.

As these are works with considerable social impact, all the principles of good building practice are being followed, taking special care over the supervision of the existing bypass constructions.