The question no one seems to be asking:

Why was the train parked on a grade and left unattended? Find the party that authorized that and you've found your "cause of accident.'

What really infuriates me though is that a simple mechanical device could have prevented this tragedy: http://en.wikipedia.org/wiki/Derail

Roll-away on a grade is a known hazard and a derail is the standard protection against this. So, why was no derail placed ahead of the train?