Two things popped into my head in reading this ..

1. Even IF the Class I's could pony up the money for such a system, what of the shortlines and regionals? Seems to me this is just another step toward some form of nationalization ("We're from the Government, we have unlimited (sic) financial resources, and we just want you to be safe and secure for your own good.")

2. Any type of PTC - whether the primo version or some kind of poor man's PTC - must have override ability for those actually driving the trains. When discussing these various railroad accidents as mentioned in the article, most of the human mistakes cited are of the passive variety, not of the active or obtuse variety. If a train driver misses a signal and PTC takes over, no big deal - that's the fail safe aspect. But when PTC is directing actions which may not be in the best interests of operational productivity, the human(s) on board should be able to make the better active judgements.