In a few simple steps you can create accurate terrain for your Rail Simulator route.

You will:

1) Identify the longitude and latitude of the starting point of your route.
2) Load a set of route markers that follow the track(s) of your intended route
3) Review the longitude and latitude of the corners of the DEM that covers your route and
then download the DEM from the USGS seamless site.
4) Load the DEM into ReDem.
5) Create the terrain tiles with ReDem and copy them to your route's terrain folder.