When the trains seem to be arriving and merging in an odd schedule.
When the train stops at a train signal that is never, ever red.
When the train stops in mid track, between stations.
When the train starts again, then brakes to a halt a few seconds later.
When the train sits there for several minutes.
When the train starts up again and goes to the next station.
When the train leaves that station, goes a few hundred yards, then stops again.
When the train motor audibly stops.
When the lights on the train go out.
And then start up again.
When someone in an RTD uniform goes trotting down the tracks from the front of the train to the back, and then back again.
When the train starts up slowly.
When you noticed that, even though your train was stopped for several minutes, very few trains passed by the other direction.
(According to the “Attention!” marquee at my final stop, there was an electrical/power problem at I-25 and Broadway, delaying service for, yes, about 15-20 minutes. Which I’m sure has all the New Yorkers and Londoners in the audience rolling their eyes at my breathless tale-telling, but it’s the first malfunction or problem I’ve run into on the LTR since I started taking it.)