With individual sections dating from the 1870s, the S-Bahn was formed in time as the network of suburban commuter railways running into Berlin, then interconnected by the circular railway connecting the various terminal railway stations, and in 1882 enhanced by the east-west cross-city line (called the "Stadtbahn", "city railway"). The forming of a distinct identity for this network began with the establishment of a special tariff for the area which was then called the "Berliner Stadt-, Ring- und Vorortbahnen", and which differed from the normal railway tariff. While the regular railway tariff was based on multiplying the distance covered with a fixed price per kilometer, the special tariff for this Berlin tariff zone was based on a graduated tariff based on the number of stations touched during the travel.