Noticing defects while underway has been automated by trackside detectors for decades, ever since the removal of the caboose and associated crewman. In this cas

Noticing defects while underway has been automated by trackside detectors for decades, ever since the removal of the caboose and associated crewman. In this case, we know the detector went off as designed, and what happened - or did not happen - next was the problem.