I’ve heard of a diesel-electric logging truck that uses this concept as well. Use the batteries going up the mountain empty, charge them again going downhill loaded.

I was on this train. Amtrak paid me a settlement not to sue them, but it’s not Amtrak I blame, it’s BNSF, who owns the track. It’s very clear from the camera footage that the track was badly misaligned by the time the train went over it at 80 mph. That line is one of the busiest in the country, and if the freight locomotives (one of which had gone over that section of track barely an hour prior) had some kind of monitoring system, they would have alerted all the other trains to stop or slow down. I used to love riding trains, but our rail infrastructure is much too far behind places like Europe.