As far as all of my previous treads go, all of my questions have been answered and all my problems have been resolved. I am now laying miles of straight track and I am spot on with the Google lay-over map of an existing railroad line which is the old Rock Island from Manly, IA to Cedar Rapids. So life is good. I have laid 34 miles of track and I am very pleased with it. However, when I ran a scenario with a heavy train I noticed that there was no difference with the hills going up or down (No trag or deceleration going up and no need for braking going down). I checked several locations on my line and I realized that, based on the information on the lower right hand side of the boarder, I had a 0.00% gradient on the entire 34 miles of track. In the beginning I had installed my DEMs into my new line but for some reason it evidently didn't get the elevation information. So now I have a question that may only require a yes or no answer. I have a more detailed set of DEM files from another project on Microsoft Train Simulator 2001 which is much more accurate. So that having been said, can I re-install the other version of DEMs to the project I am working on and still save the track I have already laid or do I need to create a renamed line and basically start over. I am OK with starting over because I have a higher level of confidence now. It is my understanding that to start over I will need a new IP Key for the second line. Is that correct?