Seoul's metropolitan area is as crowded as São Paulo's, with more than 20m inhabitants. Both cities opened their first subway line in 1974. But the transport infrastructures of the two cities are now at completely different stages. While the São Paulo subway extends a total of 74 km, that in Seoul extends over 300 km.
In Seoul, the subway is one part of an extensive and co-ordinated transport system comprised of BRT (Bus Rapid Transit), a reorganised bus system, an integrated fare structure for buses and subways, restrictions on personal vehicle use, encouragement of cycle, pedestrian and public transport use, and congestion pricing.
To alleviate funding problems, the federal government decided to subsidise part of the construction. In 2009 the 25-km Line 9 was opened. Built in less than four years, it is the first privately operated subway in South Korea.