The project consisted of the construction of twin tunnels, with galleries between them every 250 m. The ends of the tunnels are extended with false tunnels. On the Vigo side, these tunnels meet under the A-9 Highway through a section between cut-off walls, constructed with a "cut-and-cover" method.
The section has two distinct parts. The first is the open subsection between the origin of the project established at k.p. 2/200 from the parking lot defined in the survey report, which meets the junction with Buenos Aires Street, and the entrance of the false tunnels preceding the tunnel, formed by two twin tubes for a single track. The second part consists of this tunnel subsection whose exit is near the end of the section and at the origin of the next section, and which constitutes the main part of this project.
The most significant features of the project include the construction of: