A car is not a train, and I'm not a professional driver. Just saying that in my experience, it wasn't unusual for rocks and things to hit the trains I've been on... never has it resulted in sudden (or any) braking.
I accept your experience and concede the point. Even the engineer of the SEPTA train that got hit by something just minutes before the AMTRAK crash did not cram on the brakes (that I am aware of).
But, we're really going deep into speculation territory here with this... too many other more likely scenarios are possible... with human error usually being at the top of the list.
And in this case, it might be the actual cause.
Last night there were discussions that the train was doing 85mph. It was also 'said' that this was an OK speed.
Today, it is being said that 50mph is the proper speed (and limit) for that section of track.
There is a surveillance video that shows the train just prior to the crash, and several Freepers have estimated it's speed as being between 80 and 90 mph.
I would think that the engineer coming into a 50mph curve at over 80 mph might cram on the brakes.
As you say, we don't know yet. What will be interesting is the interview of the engineer.
“There is a surveillance video that shows the train just prior to the crash, and several Freepers have estimated it’s speed as being between 80 and 90 mph.”
Not this FReeper, who has actually ridden trains (including Amtrak on this corridor) and stood at platforms to watch them many times in my life, being my dad is a train nut.
Looks like plain ol’ ~60mph to me.