As nobody has mentioned this: http://www.khou.com/story/news/local/2015/08/10/train-derails-old-town-spring/31442335/
Ironically it was right at a "spring" switch in Spring, Texas. A friend of mine said he looked at the switch a few days ago and the points were very worn. We will let the investigators figure it out but it is fun to guess. The news reporter mentioned the diesel at the "front" of the train. I believe it was a DPU at the rear of the train. But how was she to know that?
Talked to the engineer of this train a few days ago and he said that the derailment was caused by a frog that had been worked on earlier that day. Total damage ended up being $3 million.
What sort of work? Welding? Replacing parts? Sounds like someone is likely out looking for a new job?