Whatever the reason for the collision, cab signals would have been a significant factor in alerting, if not preventing altogether, this. I sincerely hope that the signal was one of the new three-indicator types (can anybody post that here?). If not, it further muddies the waters as to possibilities and we don't need that further point of confusion.

The fact the the NTSB interviewed the possible witnesses is one note and when the formal investigation is released (probably next year) that input should damn well be recorded in the findings.

As for the mechanics, the fact that the switch was thrown for the oncoming freight (and bent all to hell when Metrolink went through it) is the single most important part of the investigation as the signal and the switch are both controlled by the same circuitry, although with different elements.

One small note - there are hundreds of documented occurrences of people swearing on a stack of bibles that they saw one color, when in all truth another was displayed. I only say that as "eye witness accounts" are all too often taken as gospel when in fact they should be accepted with some degree of interpretation.