"MINI ROUTES the EASY WAY"
There can only be one "Installed" from CD version of the Microsoft Train Simulator on your computer which the REGISTRY is aware of and it must contain all its 6 default routes needed for the installation of add-on Routes using an Installme.bat. New routes also can only be created by its Geometry Extractor, but can be moved to a MINI Route afterwards!
COPY the Train Simulator main folder's contents and all its sub-folders to another part of your hard drive, preferably a logical drive partition, after creating a new folder for it which can be called what you like. A meaningful name for the MINI Route perhaps and the shorter its Path then the less typing there will be when creating Desktop Shortcut target lines for it as shown below.
I created a AA-MINI-MASTER Copy to be re-used as and when. Observe the MINI MASTER's empty ROUTES folder and other missing folders not required, like HELP. The AA-prefix keeps its folder at the top of the list!
This MINI MASTER can then be copied elsewhere and given the name of the new MINI Route, adding the new route's folders to it after it has been installed in the Default Train Simulator ROUTES folder and has been tested that it runs O.K.! Route specific Consists and Rolling Stock supplied with it and not present in the existing TRAINS folders need of course be transferred to the MINI Route also.
I am using my complete TRAINS folder with the MINI MASTER which, after the new MINI Route has been created and tested, can then be trimmed to the needs of the MINI Route's activities with the ROUTE RITER, as can be its GLOBAL folder and Tsection.dat!
If you've downloaded an add-on, they should go into a common Content folder. Some people organize all of their routes and trains into a single folder, while others might organize them into regions or time eras.