Random train sound

[Peter0124]

Hi, what causes this specific and unusual 'errrrr' sound when these Scotrail units leave the stations?

It seems to rarely happen but in these three videos linked below you can hear it (particularly in the first two).

Was it caused by a rail grinder having travelled on that particular track shortly before? It is certainly niche though and I like the sound so was wondering where it came from


1st Video - Skip to 0:27
2nd Video - Skip to 0:25
3rd Video - Skip to 0:21

 

[physics34]

It certainly sounds like freshly grinded/ground rail.

 

[Alanko]

I can tell when the rail grinder has been through here as the trains have a treble-frequency whine to them and seem a bit louder. On observing the railhead in the station you can see the pattern freshly ground into the metal.

 

[Peter0124]

That's quite interesting! I find it mad a grinded rail can cause such sounds.