say i have a crossroad at (a,b) and a crossroad at (c,d) - arbitrary points on an imaginary map here. both cr's are on the surface and it costs N travel weariness to travel between.
now, say one of the above mentioned crossroads is on an underground level, but still the same x-y coordinates. is it still N weariness traveling these crs, or does traveling the z-axis (such as it is) add to TW cost?