My DEM approach...
I use Geo-data maps(DEM) & add a simple Topo map overlay.
I use the Surveyor Mini-map to view said route & trace the railroad lines, roads, etc.
This is a simular process offered by TransDEM's UTM tiles, that go under the baseboard & viewed in Grid View.
I add spline points at every hash-mark as lines delineate railroads have.
Then using trackcharts I start at the low end milepost of the route, example MP0.0, MP1, MP2, or MP693, MP694, MP695, etc. This develops track direction priority(the default direction of the arrows on traincars set-up in Surveyor).
Moving down the line, I check elevation & gradient using the Mini-map. Most of the time you can left-click the spline-point using the Height tool(CTRL+H), then the Smooth-Spline tool(CTRL+S).
In the United States of America, the average grade was established by the Baltimore & Ohio as max 1.9%...this is a rule of thumb & you readily find that many places for a short distance may be as much as 2.5%, averaged with a group of changes in a distance to lower than this.
This is why "ruling grades" may not necessarily reflect a particular grade on the same line.
It only gets spooky when you begin to make deep 30 foot cuts or 30 foot embankments & that makes the 5 meter grid in TS2009 very desirable!
Then you find pictures on the web or drive to the location & find the work you did in Surveyor is spot on!
Going back to the beginning of the route, I survey the tangents(straight track) & radius(curved track) for irregularities &
remove unneeded spline points. This is the remedy for the short quick side rolls you get on some trackwork even to the point of grabbing a spline point(CTRL+M) move tool & jerking the hell out of it one way then the next to figure the next move.
Using the Undo(CTRL+Z) tool to replace spline point then removing another spline point usually brings a consistent easement at the tangent to radius divergence.
Practice at this also benefits the laying of switches as does using the Spline Straighten tool(CTRL+B). All switches must have at least three spline points & best have the main & diverging route spline points just touch each-other for the best switch. I have found adding one more spline point not more than ten meters just before the switch works great however you must watch out on grades for a severe difference in gradient in this section of track. I find the best at track speed switch has a length of about seven 10 meter squares...enough for now.
