Lionel which made O-gauge scale (1/4" = 1ft) very popular in the US, used a 3 rail system. Other scales, G, HO, N, etc use two rail systems. I grew up with Lionel and as I get back into things, will resume with O-gauge. The nice thing about Visio, is that the track parts are custom line patterns. Don't like three rails, make a new definition.