All routes go into the ROUTES folder inside your MSTS directory. Each route lives in its own subfolder (e.g., C:\MSTS\ROUTES\MyNewRoute ).
The starting point for most players, including the scenic Settle-Carlisle Line (UK), the historic Innsbruck-St. Anton (Austria), and the bustling Northeast Corridor (USA). msts routes
Building a 50-mile route takes roughly 200 hours of work. A high-quality 200-mile route, like the "Surfliner" series, took teams of 10 people over two years. Do not start a route unless you have immense patience. Mastering the Rails: The Ultimate Guide to MSTS