The best railroad map is already in your pocket. On your phone. Google Earth and Google Maps. Before I go out rail fanning I print off a map on paper and take it with me. When I am in the field I use my phone to check my location with Google Earth.
I can see everything around my present location. This helps me with navigating rail yards . Below is a sample.
CN Yard - Pontiac, Michigan
Close-up as seen on a phone or iPad.
Hope this helps. Gary 🚂