As a first step at researching the San Pedro valley, I downloaded several data sets from the USGS. The first one is the DRG for Fairbank, AZ.
Here is a portion of the DRG that corresponds to the area I intend to model:
Right in the middle are the ruins of much of the original town site. If you look at the right side of picture, just below route 82 you will see a railroad line coming in, turning south, crossing Walnut Gulch, and going to a wye. This is the old Tombstone line which I will resurrect as the narrow gauge T&G RR.
About two thirds of the way down the picture at the left you will see a line of the Southern Pacific that heads west out of town crossing the San Pedro. This will be the line heading for Guaymas. By rearranging the wye and connecting the old Tombstone line to the Southern Pacific line I will have my new town of Fairbank.
The next step was to bring in a DEM of Fairbank.
Here is a section of the DEM that includes all of the above map:
I then took this, exported it as a 16-bit PGM, converted it to a bitmap and imported it into Bryce 4.0. I then did a simple water addition and terrain map.
Here is basically what Fairbank (minus structures, flora and fauna) looks like today:
In this view, I have circled problem areas with the 3D projection. The top one is a data anomaly, the other three are areas that were probably built up after the 1800s.
In this last view I have done a very crude addition of part of the rail line and where the bridge will cross the San Pedro. It will probably be a truss span with approach trestles. The overall width of the channel at that point is around 1,350 feet and the area that now has a bridge (between the graded areas) is 270 feet:
That is too wide for a single truss span so I will build an approach trestle and three truss spans unless I find out more when I visit the Arizona State University Historical Foundation Library and do more research, or if I decide to do a little selective compression.