Pajares Base Tunnel

During the construction process, multiple setbacks were incurred on the part of the geological conditions present, particularly the copious ingress of water into the tunnels.

Despite multiple years of remedial work and the deployment of unique engineering solutions, the infiltration issue has proved to be difficult to address, and questions have arisen as to if its electrification is even practical.

[1][2] During the early decades of the 21st century, Spain allocated a large proportion of European Union-supplied infrastructure funding into the expansion of its AVE high speed rail network.

[3] On 1 March 2002, it was announced that Gestor de Infraestructuras Ferroviarias (GIF) had awarded a €5·18m contract to Ineco and Geoconsult for the design of a new 50 km high speed railway between La Robla and Pola de Lena, forming a part of the main line between Madrid - Oviedo main line.

It has been alleged by construction workers that management had prioritised maintaining a high rate of progress over properly sealing the tunnel against water infiltration.

[11] Despite plans for the tunnel to be electrified by 25 kV AC throughout its 24,667 m (80,928 ft) length, questions have been raised if electrification is feasible due to the high level of water infiltration present.