Segovia (Spain)

Lot 2 of the southern portal of the Guadarrama tunnel, 16.7 km long, starts in the municipality of Miraflores de la Sierra with the 2,131 m long Soto passing siding and a gradient of 3%. The alignment crosses over the M-608 Soto del Real – Guadalix de la Sierra road and continues over the Matarrubias ravine on a viaduct 660 m long. At 3.4 km from the start, the tracks separate at the southern portals of the two single-track tunnels with a gradient of 3%. The tunnel crosses through the Sierra de la Morcuera with a maximum overburden of 960m (at 5.3 km from the portal) and, on reaching the highest point of the alignment, starts the descent to the end of the section.
The excavation of the tunnel, 13.4 km long and 8.50m internal diameter, was built with two double shields Ø 9.46 m that lined it with precast segments 320 mm thick, forming standard rings with a base segment and internal radius of 8.50m. Each standard ring consists of six segments in addition to the key piece.
For safety, 11 connecting galleries were built between the tunnels, spaced 250m apart, and an emergency room was designed, equivalent to a gallery 500m long with a free width of 5m, totalling somewhat more than 800m of linear excavation. It also included the building of ~300 m of signalling galleries.