The 542 kms of tunnels built during our 90 years of activity have help us avoid orographic difficulties and reduce journey times with a high level of security.

Our experience in underground works involves the development of all types of tunnels: road tunnels, hydraulic tunnels, railway tunnels and underground tunnels. All of them made possible thanks to current construction methods, such as traditional Belgian and German techniques – used heavily in urban settings – and large tunnels made with EPB tunneling machines (Earth Pressure Balance). Some examples of this type of tunneling machines are: Millicent or Ursula, used in the Thames Tideway Proyect in London, or Dulcinea which excavated the North Tunnel by-pass south of the M-30 highway in Madrid.