High Quality Content by WIKIPEDIA articles! The S-train (Danish: S-tog) network is a urban rapid transit network mainly serving the urban Copenhagen area, Denmark. It connects the city center, the outer boroughs of Copenhagen and the inner suburbs. A small number of stations reaches a bit further out, due to track extensions. Average station difference is 2.0 km for the entire system. Weekdays all stations are served at least every 10 minutes until the evening. In the city center trains depart every two minutes or every five minutes at the half-moon shaped "ringline". Sundays these time differences are doubled.