I recall the number boards on Mainline tower when I first worked there, but I also seem to recall that when that started to "bad order", they would signal you with a lantern. Reducing cabooses on the "long side" would usually be be the only reason to switch the low end of A yard. Occasionally a train would pull into the long side and change crews on 1 or 2, but even most of those were pulled down into 1 or 2 in the C yard. I also seem to recall that at some point there was also a flashing light that told C yard jobs not to fowl the lead, too?

I recall the top end A yard light was to warn you not to come out or to fowl the leads. An eastbound was usually lined into the A yard off of the main when that was on, so you were to stay in the clear.

The 20 lead was the outbound lead down along the river to the Lower end of C yard, at Dayton Avenue Tower, from the end of the Taylor outbound at the old refer yard switch. The herder had to signal you with a twenty sign, to come down to Dayton, or he could line you into the pigeon farm lead, and over the then single track bridge to the cornfield and bullring.