Complete riding is a kind of activity when a person attempts to ride all railway networks of one or more towns, states, countries. For this aim a passenger may choose an excursion train or just travel on his own individual curve without including night riding. Some passengers want to visit all stations while travelling instead of passing them. Informal competitions exist when passengers visit all stations in a definite network in the shortest possible time, for example in such places as the Subway Challenge (New York City Subway), the Tube Challenge
(London Underground).