Assets (a locomotive, a building, a weather blueprint or a skydome, for example) which are located in the folder Railworks\Source folder are not yet ready to be used in the simulation and must be exported using the Blueprint Editor.

Once you have placed your source files into the structure, have created and set up the blueprints correctly, you can then export them to run in the simulation, where a matching structure is automatically created in the Assets folder.

The default location of the Assets folder is:

Assets exported to the Railworks\Assets folder are ready to be used in the simulation. It is not recommended that files stored in Railworks\Assets be directly edited. Editing of blueprints should be done from the Railworks\Source folder using the Blueprint Editor, then exported to the Railworks\Assets folder to make them simulation ready.