Kali: Would a couple of cats and three dogs do?

Now I am having problems with trains running together on double tracks. (sideswiping each other). I thought is was the track choice I originally made (DE Concrete Clean), so I switched to Bar to San Bern mainline. They still sideswipe one another. And things were going so smoothly, (for me). Bound to be something I have overlooked. By the way, when laying track, the pop out window on the right has a "Collision" button that you can turn on or off. Any idea what that is for?