What is this? (metal bar between wheels on Dutch train; touches track when stopped)

[igloo]

Hi all,

In Amsterdam recently, I noticed a metal bar between the front wheels dropped down and touched the track while the train was stopped. Does anyone know what this is for, please? Earthing? Braking? Something else?

Here it is down:

And up:

And this is whereabouts it is:

Thanks
Ian

 

[T163R]

That's the magnetic brake, used in emergency brakings
During an emergency braking, the brake-block is pressed against the rail and a magnetic current keeps it pressed hardly against the rail.
It's used worldwide and not only on Dutch trains

 

[igloo]

Thanks!