I may have to narrow it down to one valley section that interests me most but that is still 37km x 41km. (seems smaller then some of the routes that come with RW2)
http://www.filehosting.org/file/details/219888/sltogp.kml <--Google Earth markers to see what/where I'm talking about.

This is a coal hauling service mostly, it was consructed by the Alberta gov't in the late 60's and "given" to CN to operate, CN has since purchsed the line, sold it and repurchased it back again. It starts outside Hinton, Alberta near Swan landing and goes north to service the Grande Cache Coal corp's mine, then continues up river valleys to the city of Grande Prairie and a few communities from there. The coal is shipped out to the west coast and off to Japan for use in the steel industry (metalurgical coal, not the stuff for power plants)
So far I'm a complete noob, I've had RW2 a couple weeks and played maybe 10 scenarious plus done a lot of free roam. What I really want to do is create the above route. Is it really THAT BIG in comparisson to most others people create? Is it outside the parameters of whats possible? I'm still messing around trying to get my terrain/decals the way I want them. Terrain seems ok, I have to do a more thourough fly around (with the marker file that outlines the track) to be sure because flying around now with just RWdecal markers gets me lost and disoriented, but I do believe ReDem did render just tiles within 2-3 (cant remember which one I set) of my route because I do fly off the terrain onto flat ground in certain places, for a while I thought something was wrong, until I realized thats probably for the best, I dont need terrain far from the tracks. (334 terrain files vs 1979 files if I let ReDem model the whole area)
My current dilema is in getting decals (so that I have some way to orient myself besides markers) RWdecal wont "get chunks" for the whole map, thats 20k+ files and it runs out of memory after a few hours. The most I was able to get it to process was 9700 when narrowing the route down to the single valley, still I dont need decals for the terrain not renereed by Redem away from the tracks. Is there any way to have RWdecal only process chunks within certain # of tiles of my route markers like ReDem did when rendering terrain?
For now I have to play with markers, reload my large marker file with the route-line drawn in GE to make sure I at least have terrain near my tracks, then I can play with the decals, maybe making just a few at a time in key areas to get me started.