The fact that the sound will arrive much faster through the rail was not presented as having practical value in this scenario. The delay is merely an interestin

The fact that the sound will arrive much faster through the rail was not presented as having practical value in this scenario. The delay is merely an interesting fact of physics to observe, just like observing the delay from lightning to thunder can be interesting. As for energies, I used a short example of 500 meters to make it more probable, but near ~150 meters you still have around half a second of difference, which is more than enough to notice.