I don't think there was any element of terrorism in last night's derailment in North Philly.
Looks like the engineer missed the slowdown, seems like the train ran into a 50mph restriction (curve) at around 100mph. Not going to stay on the rails like that. You can see what happens to a train when it enters a curve 50mph over the limit.
This is reminiscient of a bad derailment that happened in Bridgeport (CT) 'way back in the 1950's. Eastbound passenger train running about 70 hit the "Jenkins curve" (30mph) without slowing down, jumped the track, engine ended up crashing into a switch engine in the adjacent freight yard (and killed someone on the switch engine, too).
There are some slowdowns you just can't afford to miss.
Jenkins curve was one of them.
BTW, the fireman in the Bridgeport wreck was a young guy who survived (engineer was killed), he had gone "back into the engine" (electric) to take care of something. He went on to lead a long career right up into Amtrak, and I worked for him when -I- was a young fireman back in 1979. He's gone now.
Amtrak had installed "enforced cab signal drops" in certain locations approaching critical speed restrictions, but the curve involved wasn't one of them.
I can see several possible causes:
- Engineer lost situational awareness, didn't realize curve was coming up
- Engineer knew curve was there, but waited too long to brake for it
- Possible failure of electronic braking software or hardware (possible, but unlikely).
(In the old days, when you moved the brake handle, you were moving a valve that directly controlled air pressures. Today in modern equipment, you move a handle that is connected to a computer, and it uses software to govern hardware that controls brake pipe pressures).
They are scheduled to perfect the non-derailing train just after they invent the plane that can't fall from the sky, and the unsinkable ship...