Prometro, S.A. (ViaPorto), a company owned by Grupo Barraqueiro, Arriva, Keolis and Manvia, was Metro do Porto private operator, responsible for the operation and maintenance of the system between April 2010 and March 2018. Metro do Porto is one of the largest light rail networks in Europe with over 60 million validations in 2017 (an all-time record), 6 lines, 82 stations (14 are underground), 102 vehicles and 67 km railroad extension (7km of tunnels).