Some interesting maps for train line from across the world. Why is this important? These maps demonstrate different ways of communicating and how important it is to be clear when completing graphic designs. Theres a lot to learn from clear train line diagrams.
"Good design is not found by picking from a pack of arbitrary options, but is rather the result of deliberate, contextual choices."
This quote is taken from a great article on some of the major questions new designers ask. Read it, and get some great insight on the industry, it should give you a realistic understanding of some of the ways in which the industry works.