Wikipedia: "The S-train (Danish: S-tog) network is a suburban rail network of Metropolitan Copenhagen, Denmark. It connects the city center with the inner suburbs of Copenhagen. The first line was opened in 1934. Today the network forms the heart of the public transportation infrastructure in the city, serving more than 357,000 passengers a day. It is entirely owned and run by DSB S-tog A/S. As of January 2009 there are 170 km of dual tracks and 85 S-train stations."