Actually the smalltrain came from the tracks along Blue Island, crossed Ashland, then turned slightly right along with the tracks (as trains do), following Cermak.
I stumbled with my bike out the front door and heard smalltrain making smalltrain noises. I've always been something of a smalltrain skeptic and thought that the train noises were more likely to come from the tracks on the embankment north of 18th, or some other, less run-down set of tracks in the industrial area near the Chicago Sanitary and Ship Canal (local euphemism for LOL @ St. Louis, were in ur river sendin u sewage... and then they sued us). But these noises were definitely close and definitely coming from the south. It had to be smalltrain.
I saw smalltrain looking down Paulina as I pulled onto Cermak, and got to the corner of Ashand, Cermak and Blue Island just after it. There aren't gates along smalltrain's tracks, and I didn't notice the crossing signs flashing or ringing (though they may have been drowned out by the sun and smalltrain's frequent horn outbursts). Either way, traffic on Ashland wasn't stopping for it. So smalltrain had to wait for the light at Ashland. It proceeded with the Cermak traffic's green. I tried to ride slowly to not get far ahead of smalltrain. I just wanted to see if it would actually travel along the overgrown and under-maintained track on Cermak. I could hardly help but pull away (it's hard to watch a train while biking on a major street without being a severe nuisance). Then when I reached Loomis I noticed that smalltrain was going back the other direction. I carefully looked at my surroundings, recklessly pulled a u-turn, and tried to chase smalltrain back west. But its engine was retreating past Ashland, down the better-hidden tracks along Blue Island. And following it would have meant going the exact opposite direction as going to work. So I abandoned smalltrain for today.
EDIT: also, I win. And smalltrain's engine is blue, in case you were wondering.