The track survey is the next thing to do for the first route planned. To do this we need to find data on exactly where the track is in 3D space. Where is it located relative to the objects in the environment around it? What are the gradients along the track?
Then there are the art assets, such as the dimensions of the track and sleepers and textural qualities of metal and wood, along with track ballast, dirt and other rocks nearby. The vegetation, animals, people and buildings can be added in later.
Locomotives and rolling stock are an essential part of early development, for a track without something to run on it is not much fun. So more data has to be gathered for the virtual construction of real objects. Engineering is engineering and a realistic experience in the virtual world depends on accurate recording of detail in the real world.
So here we go, with the 5% inspiration and the 95% perspiration just starting. Yet the work is only one part of it, for any project of this nature depends on good luck as well as good management. The good will and assistance of the larger community will determine the outcome of this project.