“even with the brakes on all the cars in emergency”
Would better brakes have been a good thing here?
Well, you can only stop something so fast. Just like your car, the weight of the car causes you to not be able to stop all that quickly. The more weight, the longer it takes to stop. So, the brakes go into emergency and the air pressure into the brake system and the brakes start rubbing on the wheels. It would be worse of the brakes locked up the wheels because then it would slide or skid just like a car does.
I really don’t know and qualified my comment with “if”.
Had read earlier that it was, see here the NYTimes attributing it to the wheel bearings:
“The N.T.S.B. said its investigation included examining tank car fittings, the locomotive event data recorder and surveillance video from a residence that showed what appeared to be the failure of a wheel bearing moments before the derailment.”
https://www.nytimes.com/article/ohio-train-derailment.html
It seems quick to have a conclusive answer and I don’t have the expertise to make a connection between the two anyway.