I’m sure there are a lot of factors that added to this tragedy, however, it would seem that the largest factor was the lack of brakes.
The brakes would have kept the train where it was far outside of town.
As far as I know the air pressure in an air brake system is used to TAKE OFF the brakes which are failsafe and otherwise always ‘on’. Rip the brake lines out of an air brake system and the wheels lock.