“According to the railway, the trains locomotive was shut down subsequent to the departure of the engineer, depriving the trains air brakes of the power needed to keep the load from careening downhill.”
I’m surprised these brake systems aren’t designed like trucks where the air keeps the brakes OFF. Failure of an air line or compressor would mean the brakes lock up.
" Joe McGonigle, a vice president at Montreal, Maine & Atlantic, said the train came loose in the early morning hours Saturday and started rolling down the tracks.
He said the trains engine was found about one kilometre from where the explosions took place."
It would make sense that all 5 locomotives came through town before the tank cars and with their lower center of gravity(?) and higher weight were able to make it through the switches with out derailing.
Once thederailled cars stopped pushing them, whatever brakes they may have had set could stop them from going uphill.