Looks like 24" gauge to me and there is a lot of it. Quite a bit doesn't look like it has seen any use in a long time. Too bad the photo doesn't extend down farther to see where those couple of tracks go. When they pull the cars out of the retorts they normally let them drip before unloading them. Running a tractor through that mess would probably be frowned on. Note your Colorado photo shows the whole track to the retorts is a confined area.