"O" gauge two rail

I’m new to model railroading, I was reading an article in “Model Railroad Planning” about two-rail “O” scale modeling. I’m not sure if the author is talking about narrow gauge modeling (on30) or what. Can anyone steer me in the right direction. I have the room to model in “O” scale but would like to do it with two rails, instead of three.

Thanks Roland

Two rail O scale is at least as viable now than it has been in the past. Atlas has a line of track and rolling stock for 2 rail. This site http://users.foxvalley.net/~osn/ should get you have to a good start.
Enjoy
Paul