The train stopped in the length of the train… that would produce a deceleration similar to a 70 mph car jamming the breaks, or less
The train took the length of the train to stop… not instantaneous.
In the trade, we measure deceleration forces by the injuries caused.
Few injuries , ergo slow deceleration.
Not ONE cracked skull… 70 mph to 0 mph in a distance of 400 feet