Here is the rules doc for LIGHT RAIL if you'd like an early look. I appreciate any clarifying questions or notes you might have since this was a very tricky game to present in print.
Explaining the city limits was the hardest part since I'm so accustomed to explaining it in person, where I can use body language and verbal cues to communicate much more easily.
Here is a screencap of the two pages which explain city limits:
I tried to convey a physical space first by using one human hand as a frame of reference. From there, I introduced a simple, legal placement. Then I examined two other options for placement and explained why they were illegal. Finally I wrapped up with two other legal placements which would have more complicated consequences for other spaces on the board.
I imagined this as a spiral, taking the simplest situation and spinning out to progressively more distant edge cases. I hope that was all clear! Again, if you'd like to review the whole rule doc, I'd very much appreciate it!