http://forums.auran.com/trainz/showthread.php?t=35921&highlight=basemap
http://i525.photobucket.com/albums/cc339/cascaderailroad/GoogleBasemapJpg.jpg
 
Does a blank basemap show up in surveyor ? You can raise the height if it is hiding under the baseboard.
 
Basemaps are flat, and will not conform to a DEM contours.
 
Basemaps can not be rotated, so make sure the baseboard and Basemap are orientated to a North dirrection.
 
There are other smaller basemaps, which I am unskilled at using, that are the size of one Trainz baseboard.
 
Basemap A-Z, 
0-9 are larger than 1 baseboard, so you will need @ 4 square baseboards per basemap.
 
To more easily manipulate and slide Basemaps around ... In your Trainszoptions file, add the line 
-surveyorfov=155 (which will give you a fisheye view). You an always set this numeral as high as 
=185 , or set it back to default of 
=55 .
 
I cloned BasemapA over 200 times, and renamed in each of their config file: 
username-Basemap_SouthAltoona ... etc ... etc.
 
Using the MS Snipping Tool (in your PC Accessories) Google Earth has a Tools/Ruler/Metric/KM/Path tool where you can draw a 1x1km box to snip.
 
Edit in Explorer: 
BasemapA, and using MS Paint, paste a 1km x 1km image in the 
BasemapSquareA image, that you have snipped from Google Earth or a topo map.
 
Save and Commit the asset.