Automatic train stopping device

[Scoobie]

Hi everyone, I was at a Model Train Show, on one of the layouts they had a section that would stop a train if another train was coming across the same section of track, and then continue after the train has passed. Can you please tell me what this device is called.:thumb:

 

[LoudMusic]

It was likely a DCC system computer controled with sensors on the layout to know where trains are located.