Pajares Tunnel

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 main part of the project is the execution of the tunnels between La Pola de Gordón and Pedanía de Folledo from the southern mouth, with a 10,192-metre long right track and 11,369-metre long left track. The finished circular tunnel section is 8.50 metres in diameter.  

The two double telescopic-shield TBMs start at the southern mouth and execute two substantially parallel galleries, separated by some fifty metres, with simultaneous tunnel lining with prefabricated reinforced concrete voussoirs, with characteristic strengths of 40, 50 and 60 MPa, 50-cm thickness and concretes of characteristic strength 

In order to ensure compliance with the established deadlines, a two-kilometre long access gallery to the section is being executed using conventional methods that commences at Folledo (León) and, with a 13% slope, it meets up with the main tubes at their kilometre point 7.7. Execution of this gallery commenced a little after the works were initiated so that, while the TBMs were being manufactured, it was advancing towards the meeting point with the main tubes. A cavern was executed at the gallery meeting point with the main tubes to make it possible to dismantle the two TBMs that would reach this point from the southern mouth at La Pola de Gordón.

The remaining 2.5 kilometres are being excavated and supported using the new Austrian method, with pumped concrete lining, from an intermediate point that is accessed by the Folledo inclined gallery.

Remarkable aspects

  • Improvement of communications between north and central Spain.
  • Very complex works because it runs underneath a gas pipeline and because of water pockets.
  • Despite the orographic difficulties, the mean performance was sixteen metres per day in each tunnel.

Client: Ministry of Development

Start date: April 2004

End date: March 2011