Hi there. I am going through the following tutorial:
When I get to the ‘Create the rails’ part I run into a problem. I create the rail with the bezier curve, and I duplicate it and then join the two rail bezier curves to form one object. But now when I set the ‘BevOb’ in the bezier path to my newly created (joined) rail object I have a problem. One of my rails (the one sitting overtop of my path looks fine) but the other one has gone crazy and seems to have twists and knots it shouldn’t.
See the picture…
I do not have a technical explanation for this as I am still new to Blender, but I would like to share how I resolved the problem. I had a hunch which turned out to be correct, that the size of the rails was too large for the bezier path that they followed(I think that the cross section area was too big  for the length of the curve they followed. So I went back and made a longer track and voilé, the rails came out okay. Btw way there were still some sections of my rails that looked like they might have small undesirable twists like in my first attempt. These went away when I smoothed out the turns in my main bezier curve path to be less sharp.
I finished the tutorial btw - and I think it is a very good tutorial and makes you feel accomplished once you are done. I recommend it.
Thanks for the advice atom. I selected my bezier curve and chose a vertex and hit T and started moving the mouse around. Although my tilt in the lower left corner was changing, nothing was happening to the rails. I suppose I will have to read up on tilt in the blender manual.
Lot’s of branches to get lost in during the learning process, and by the time you back up to where you started, you have no idea what you were doing ;-).