If you’ve ever drive like a demon, you know that you can’t brake driving your car through a curve. If you do, you’ll throw your car off the roadway. The momentum would make the top of the car lean off the road, over you go.
If the brakes of the train had been applied, I would suggest it would have been even more likely to go outside the curve, with no cars winding up on the inside of the curve.
You have to moderate (bleed off) speed in the straight away. Once you’re in the curve, the die is cast. You just hang on at that point, and hope for the best.
For auto tires, look up “Friction Circle”.
Im thinking breaking so hard and fast the cars in rear ran into cars in front.