The four drawings below show how a basic three rail automated systems allows two trains to run on the same loop. This is basically a continuous system which makes it very suitable to shows and public displays. It is a popular system for model tramway enthusiasts as the regular stopping and starting simulates a typical urban tramway.

For traditional model railways it works well where one train, that stopped, is hidden. One train enters a tunnel and another leaves. For a narrow gauge system the tunnel can be a mine. Of course there are many other industrial situations that can be considered.