From the pictures, it appears that the derailment probably started several dozen (or hundred) yards before the overpass and it got out of control by the time it got to the intersecting road. I wonder what the chances are of a train derailing right at the intersection with a road? I wonder how many hundreds of miles the train passed before derailing so close to an EASY ACCESS POINT?
If a train track were to be sabotaged, I would assume that it would occur several dozen (or hundred) yards off of a road that would allow the criminals easy access and then easy escape after planting the impediment.
Going by the extensive graffiti I would say bad people have a lot of time to do anything they want there.