The turnkey contract involved the design, construction and operation for five years of the whole new transportation system for Oporto and neighbouring towns. The light subway serves approximately 2.5 million residents and consists of two urban lines and two non-urban lines, for a total length of 73 km, of which about 36% is double-track line.

Approximately 5,700 m of the line is underground. Excavation of the tunnels in a densely populated urban area, with the need to monitor possible surface subsidence, dictated use of earth pressure balance type tunnel boring machines. The work was executed with two full-section EPB-type TBMs with diameters of 8.70 m and 8.90 m respectively. A tunnel connecting the two main underground lines was excavated with the NATM method.

Eleven new underground stations were also constructed, each one of a different size and using different construction techniques, as well as 56 above-ground stations; of these, 22 are completely new and the remaining 34 were renovated.