stop signs on tracks

[kaesthebluntedwonder]

today i noticed that there were metal stop signs (square ones, not the octagonal ones you see on the road)...they were attached to a metall rod which had a clamp at the end and attached to the rail. there were a few of these here and there, i think before the track got to a switcher (correct me if i am wrong, i mean the part of track that you can switch to have the train go onto another track)...what are these used for? (besides to tell the train to stop...i thought maybe there was something more involved).
thanks

[Ski Mask]

it was blue right? thats to tell any approaching traffic that somone is working on that track, and it is essentially "off-limits" to any movement.
When joe brakeman gets a call to fix a brake valve on car x on track y he goes out, flags the track with that blue stop sign, does his work, then goes back and removes it. This is done so his ass wont get cut in half when some idiot tries to hump a car onto the end of the string of cars hes working on. Railroad rules dictate that the only person authorized to remove that blue sign, is the guy who placed it...safety first!

[kaesthebluntedwonder]

yeh it was baby blue and just standing attached to a rail on a track. my yard is small and usually when im there i dont see anything going on at all, so it must have been from the previous nite im guessing.