The implementation of tunnel solutions is frequently imposed by stretches of railway and metro lines, high-capacity urban and intercity highways and the optimisation of the layout of these infrastructures. Likewise, water supply networks, mining and energy supply also require underground solutions, which are now possible thanks to powerful tunnel boring machines that can drill tunnels in a single section, used in conjunction with more traditional tunnelling methods and techniques.
RRC has extensive experience in the construction of underground infrastructure, particularly in the construction of different types of tunnels for roads, railways, inner city metro systems, etc. Former works include a set of large-scale tunnels excavated by tunnel boring machines, some of which are still being used by the group:
- "Tizona", the largest tunnel boring machine worldwide, was used to construct the tunnels of the M30 in Madrid. With a 175 m width and weighing more than 4,200 tonnes, it can produce a thrust force of 31,700 tonnes and has a daily capacity to drill 24 m of tunnel with a 15.2 m diameter.
- LOVAT, the 9.8-m-diameter tunnel boring machine known as the "Eastern Star", was used to drill the red line between Alameda and Expo in Lisbon in 1997. It was later given to the Lisbon Metro to complete the rest of the red line.
- Ramela Tunnel, on the Guarda / Benespera section of the IP2
- Gardunha Tunnel, on the Alcaria / Soalheira section of the IP2
- Montemor Tunnel, on the Pontinha radial road / Odivelas radial road of the A9 – CREL
- Tunnel on Av. Infante D. Henrique, Lisbon
- Tunnel on Av. João XXI, Lisbon
- Ceuta Tunnels, Porto
- Aguas Santas Tunnel, Maia
- Red line between Alameda - Expo, Lisbon