I read that he left the station sixteen minutes behind schedule. He was speeding to make up time. If the speed limit was 50 on that turn, like on a highway the turn probably could be taken in relative safety at 70 or 75 mph and in a pinch, it probably has been taken at 90 mph fairly regularly.
He just screwed up and was going too fast and then panicked. There was a retired Amtrak conductor on the radio last night who said that the train would have made that turn at 106 mph without too much problem except that he panicked and hit the emergency brakes. The brakes work from front to rear with the front cars slowing down first. Hitting the emergency brakes going that fast into a turn like that made all the back cars pile onto the front cars that had already slowed down first and caused the derailment.
It is like driving a car, the worst thing you can do is panic and lock up the breaks going into a turn.
No railroad curve is good for double the speed, even with relatively light passenger equipment. Maybe it would hold at +25ish. Nobody regularly takes curves or violates max speeds, especially not by more than 10mph over max speed. FRA takes their card for 30 days first offense and a couple more times and card can be gone for years.
