During the last decades of the 20th century the increasing number of cars made Porto the scene of an almost continuos enormous traffic jam. The buses were stuck in the jam too. The remains of the old tram system, in decline since 1959, were not suited to provide a base for high capacity public transport. But Porto was considered too small for a full scale underground system. It was decided to create a new light-rail system in tunnels in the central area of the city and at surface outside the central area. For this a new organisation was created, the Metro do Porto.