Question: Why didn't the prisoners unhook several cars at the rear of the train, to roll down the tracks and crash/block the troop train coming up behind them towards the end?
Question: Why didn't the prisoners just walk through the tunnel to Switzerland on the other side?
Answer: The majority of prisoners were heading towards Switzerland through the tunnel, only a few prisoners with weapons were acting as a rear guard to hold off the German troops chasing them and buy the prisoners time to escape.
Scott215
All the prisoners were on the train. I've contended before, they didn't need to fix the track. Just leave the train on the bridge and go straight through the tunnel. That route HAD to be shorter than going around on the walkway, and they would have had a much larger head start than waiting to fix the track.
kaevanoff