F40 wrote:Any "failure" of the brakes may come from any input failing to heed to the engineer's control (I am not sure how likely that is), not from the fail-safe mechanical mechanism of the brakes itself. If you have little to no pressure in the brake pipe or if the compressor was not making enough air and it drops below the threshold, this is akin to putting the train in emergency, and you will simply not go anywhere. Unless something miraculously caused the brakes to fall off from all the axles of the train, it will be generally very hard to blame it on the brakes. They should be tested as part of the thorough investigation, but I would not say it is such a "hot spot" to look for when listing possible causes of mechanical failure.When was the last time there was an actual brake failure, either in freight or passenger service?
Excluding the runaway in Canada, which was human-caused, it's a very very very rare event.