Its possible, but don't expect fast results. I use a serious pc with 10 TB of drive space, and I have made some large transdem routes with entirely too many maps.... And At times I had to leave my pc for 4 hours only to return to an error message, and repeat until I found all the limitations of the program, and figured out ways to work around them. When you run into a limitation you will just get a error, which never helped me with figuring out the problem.
A set of tools is helpful when dealing here.
Microdem helps with the dem data and merging dems, if you have 40 dems, transdem will only merge 1 at a time, have fun times 40.
Microdem will merge all 40 properly(with program errors) And does it with you only selecting merge dem, and all 40 files in one action.
WinRAR lets you work with many compression formats, like .rar
An account with free dem data services like,
https://viewer.nationalmap.gov/launch/ to get dem data and even topo maps and the like.
1/3 arc-second DEMs are available for all of the usa and canada.
FOR THE USA, i guess they don't have outside the us, why not the damn satellites orbit.
Signing up with googles signature service(free) will let you download many more daily google maps than the free daily limit does.
A higher speed internet connection helps for all the dem data and ground maps.
Don't expect the results to be clean with the maps you apply in transdem, they are ment to be guides for placing your objects and ground textures.
The maps transdem puts down, are processed improperly by tane which causes graphic glitches in the transdem terrain map in the far distance.
You can see the discussion on the issue here:
https://forums.auran.com/trainz/sho...ireframe-view-in-driver&p=1652364#post1652364
It is very fun and rewarding to be able to drive an entire route before even adding anything with tane.
This will allow you to see the way the landscape looks, and if you need more dems from a specific area that shows landscape gaps when you are on your rail line.