I didn't mean to speculatively blather about a possible lack and/or failure of PTC. I just wasn't properly distinguishing "commuter rail" vs. LRT amid all the recent "blather" about Denver's grade crossing protection problems, highrise buildings causing interference, etc, etc.

Rather than blather, I was just curious if this might be the first (seems bound to happen eventually) apparent PTC failure which would, of course, result in lots more cries for action, etc. Of course it would probably just take a kinked air hose or closed angle cock, insufficiently charged train with high TPOB, or yes, maybe even adverse rail conditions in connection with the right chain of events.