The construction processes planned for the execution of the underground lines are:

• Cut & Cover, in the section between Nazaret and Plaza del Ayuntamiento, and in the stations.

The tunnel will be created by building some screen-walls to provide both provisional and definitive support of the land. Depending on the geo-technical features of the land, these screens can carry out the complementary function of preventing the flow of groundwater from reaching the tunnel during the excavation phase. Prior to the excavation of the tunnel, the roof slab will be carried out over these screen-walls, which allows for quick restoring of the affected traffic while serving as bridging for the retaining walls at the same time.

• Tunel Boring, in the section below the historic centre, from Plaza del Ayuntamiento to the old Turia riverbed.

The tunnel will be created using an Earth Pressure Balance shield, injecting mud and, if necessary, surface-active foam to remove the sandy gravel underneath the groundwater level. The work using this system is fundamentally underground, except in the stations that have to be built using the cut & cover method.