I've been to about a dozen fatal accidents in my career, this has all the aspects of either straight out human error, or of some strange combination of multiple system failure.

I'm aware of what is possible with advanced ATS systems, especially with our current GPS and computer technology. ATS should be required and in-vehicle signal aspect display, and in the event of failure to respond, ATS should stop the train. Pending some other explanation, those kinds of systems, would have likely prevented something like this, or likely minimized any causualties significantly from impact.

FYI... There is no indication that either crew was able to take any action. UP was going through the short tunnel and had just emerged at point of impact. They appear to have had almost no time to react.