When modeling and railroad in ariozna there are few chosics to make.
The first choice is which one to choose. But it is only one big one. BNSF goes north to south and east to west, connecting the main cities of Arizona. They combine all the other railroads and connecting Arizona to other states.
The second goal is what period. For the most part, BNSF has the same ballast in the same location as in the past. They mostly use black cinder over most of the line. That makes it easy to choose.
The Third choice is location location location. In Arizona, they have many different types of terrain. In the south, they have open and flat desert. In Central, Arizona, they have urban to mountain terrain. In the north, they have mountains and the Grand Cayon.
If you include the Grand Canyon, you will need to have a structure the goes well below the leading layer of the track.