Part 3/9:
Faced with these challenges, Porto's public transport agency, STCP, began exploring solutions in 1989, deciding to invest in a semi-Metro system—a hybrid between light rail and traditional metro that would utilize underground tunnels in the city center while operating on the surface in suburban areas. This decision was grounded in several critical factors: the flexibility to adapt to Porto’s medieval shape, the limited budget that followed Portugal’s EU accession, and the growing popularity of light rail systems elsewhere in Europe.