The Pajares Tunnel forms part of the project for the new León - Asturias high-speed line. These tunnels make up the most technically complex operation on the High-Speed line, which forms the connection between Madrid and the principal cities in Castilla y León and those of Asturias. Its construction is intended to cross the Puerto de Pajares massif and it reduces the current journey distance by rail between the two slopes of the massif by 34 kilometres.
FCC was the successful bidder for Batch 1, which consists of the works required to establish the international width double-track platform for a speed equal to or greater than 300 kilometres per hour, together with the replacement of affected rights of way and services, environmental integration and complementary works.
The project entails the execution of two, 24.6 kilometers long tunnels.
FCC excavated 15.05 kilometers on the right track and 9.85 kolometers on the left track.
The entire tube was made with two single shield, articulated TBMs. This work presented a great technical, engineering and construction challenge, becoming the sixth longest railway tunnel in Europe, the seventh in the world and the second in Spain behind the Guadarrama tunnels.