Hi Rick,
For me making tracks is easy as I have just three rules in my head...
Similar to what Peter said.
1. The Top vertexes of the rails shall always be at Z = 0,3 meter -> ALWAYS
2. The inside top vertex of the rails shall always be the same distance along the positive and the negative X axis as the gauge determine it to be and always at Z=0,3 meter - the rest of the rail mesh is determined by the weight of the rail according what rail I'm modeling as a 60lbs rail looks different from a 120lbs rail.
3. All models start at the Y axis = 0 and goes down into a negative Y value.
With those three rules I build any track the way I need it to be, sometimes that means part of the track might be above 0,3 meter (if I build a cut into a track for instance the rail is left at 0,3 meter but further out on the sides I put the rock part of the mesh higher...)
Or, if I model a bridge/trestle with built in barrels, the top of them would be higher then the 0,3m rule for the rail it self.
Most of the model of a track, especially a bridge, would be built downward into a negative value on the Z axis, but all that don't matter in the Trainz world as long as the rails are at the values specified above in the 3 axis making up our little 3D world...
Have fun with my mesh Rick, I can send others if you like where the ties are actually modeled into the mesh better then the one you got, where it is partly part of the texture and partly a mesh model of a tie...
Have fun all, hope I didn't over shared info and confused anybody with the above text.

The three rules is enough really - but then again, I always thing X, Y, Z when modeling - maybe that was the reason I couldn't do any "real modeling" girly style.. LOL
Linda