Historic preservation officials and archeologists are not always aware of the significance of what they see. Most of them are more tuned into prehistory than industrial history. They can recognise an historic building, but railroads are generally out of their area of expertise. I have seen that a number of times in my work with National Forest roads. I have had to relocate proposed roads because an obsidion flake was found on the "P line". I do not argue with this because it could indicate a significant site, and once we dig it up it is gone. But I have seen a number of cases where railroad and/or logging artifacts were mis-identified, and labeled as "not significant". In one instance a Stoddard Lumber Co log car was called a "machinery frame". Fortunately it was not in the way of anything and is still there. In another case a two span log stringer bridge with a log crib center support was called "not historically significant", and a road was built right through it. Had I been involved the road would have been moved over 50 feet, but the locator in that case believed in neat lines. I once had to pad over part of a camp spur even though the road was already existing. But then the logging administrators, with approval of the archeologists, put a landing exactly in the center of the camp site. The evdence at that point, which had included a switch and short spur, was very faint. The landing of logs and subsequent burning of slash completely obliterated it.
This does not necessarily apply to the C&TS situation, but the point is that anyone with an interest needs to be vigilant. As related in the above posts, the people who can do something might not know about it.