It's kind of a pain to figure out what type of road/rail lies are in each pro. Maybe use the following.
1) Keep just a straight line for roads. (keep as is)
2) For level 1 infrastructure make the road/railroad lines thicker and darker. (dark black)
3) For level 2 infrastructure make the road/railroad lines, as above but with a cross hash that looks railroad ties.
4) For level 3 infrastructure make the road/railroad line as #3 but double tracked.