Technically, an uploaded route contains only the terrain and the location and identities (kuids)of all the assets (including track and track objects, scenery, textures, etc) but not those assets themselves. This also applies to rolling stock if you have included it in the route. I normally put all rolling stock in sessions.
When a user downloads the route their CM will then search for and download from the DLS all the assets (including rolling stock) that have identified as being part of the route that they do not already have installed in their local Trainz/TANE folder.