Hi: I've seen ballast, of course, not only under the sleepers but also among the different tracks. The workers can be seen walking on the ballast. But what about open spaces, i.e., around workshops, towers, or the parking lots? May I leave sand glued to the board? Or earth? Or paved ground? It is an American freight yard running DRGW and UP freight trains. English is not my language so please excuse me if I cannot find the proper words or concepts. Thanks
It really depends on the specific location being modeled, and the year. Basically, the answer can be “all of the above” although areas where workmen would be walking would have been more packed down than just ballast (for better footing).
...though bare earth was most common. In fact, if the yard is not a big, major facility, it may be that only the through tracks are properly ballasted, and the storage tracks are slowly sinking in the mud.
Here's a stupid thought. There are several prototype photo sites there are many pictures showing engines in the yards. This will give you a basic idea of what you may be looking for. Utahrails.com has UP/DRGW pics plus others. myespeemodeler site has decent pics of both SP/DRGW pics. rr-fallenflags.org a site i support has dedicated sections for each railroad including a UP SP DRGW area that show some decent yard pictures. Hope this helps some
What'd your chosen location and era? Knowing that will help us narrow it down further for you. If you don't have a specific place in mind, we would help you find typical practices for D&RGW and UP.